For me, things have moved on since ëpre-amp fun and gamesí ñ well, they have since yesterday, anyway.

ëFun and gamesí put forward the notion that you can only get so far with super-supplies and regulation. The other half of the supply (the 0V return half) needs at least as much attention, if significant progress is to be made. Ultra-low impedance 0V power supply to pre amp links were tried, followed by the split 0V rails. I think itís safe to say that anyone whoís tried the split 0V mod and those who have gone further using multiple transformers with multiple 0V returns, would agree that there is much performance to be gained by looking at this area.

Lately Iíve been thinking that something more radical needs to be tried- something that may actually provide the ultimate 0V return path ñ no path at all! So, how can this be done? Simple. Let me introduce to you this most wonderful of creations, the DC-DC converter.

Put simply, this device is a miniature switch-mode power supply. It takes in DC, chops it up at high frequency, and passes it through a tiny isolating transformer, finally rectifying (and usually regulating) it back to DC. The bit weíre interested in is the fact that it completely isolates both legs of the input DC, from the output DC. This means that if the device is placed close to the star 0V point in the pre-amp, the output ñVe can be directly linked to this point, creating the ideal 0V point. This is the ideal power supply scenario ñ where the power supply 0V and pre-amp 0V are one and the same. Itís the equivalent of having the whole power supply right inside the pre-amp.

There are other benefits too. As these devices ëregenerateí DC, they are pretty much immune to the quality of supply feeding them. No need for a Hicap or better, just a simple linear supply will do nicely. Something like a single rail Snaps would be ideal. Also, poor mains quality will not be an issue.

In my 102, Iíve fitted two converters, one per channel of line stages. Each converter feeds the existing three local 1086 regís per channel. The model of converter Iíve used is the Traco (http://www.tracopower.com/products/index.htm) Ten 5-2423. It can operate over a range of IP voltage, and outputs +/- 15V, though I simply take 30V from across the outer legs to power the 1086ís. The primary 24V supply Iíve used is a simple one ñ probably more basic than a Snaps. The important thing to note here, is that the 0V of the primary supply must be taken directly to the converters, and not connected to the pre-amp in any way. This arrangement has made redundant a heavily modified Hicap, fitted out with six SRís and split 0V.

How does it sound? Really, shockingly good. Everything about the music is better. There is an obvious extra layer of detail, with instruments and voices sounder purer and more ërealí. The dynamics are bolder from top to bottom, with cymbals sounding clear and sharp and kick drum being felt firmly in the chest as well as the ears. Every piece of music Iíve played has struck me as being better emotionally portrayed, than Iíve heard before ñ so itís not just a ëHiFií thing.

I canít recommend enough that you give this a try. It requires you to leave aside some well established ideas about what makes for a good power supply, but keep an open mind and give it a go.

Mr Tibbs

Mr Tibbs,

These DC converters sound relatively small, and yet sound like they have v. low output impedance, even with a modest supply. Is this so? I believe your ears but it sounds like we are getting something for nothing.

Regards,
David
"let a hundred flowers bloom"

David,

Yes, they are small. The type I'm using have a regulated output, so (in theory anyway) the output impedance is low. The primary supply used will (within reason) make no difference to the function of the convertors as they use SM technology.

I tried them as a means of solving the 0V return riddle. Naim spent a lot of time designing preamps with very extensive star wiring, only to blow much of the benefit by having the PSU 0V point three feet away from the preamp. The DC convertors eliminate this problem.

On the +Ve side, as far as regulation goes, the converters will not be as good as say SR's, but there is nothing to stop you using SR's along with the DC convertors.

I have deliberately kept things simple, to see if solving the 0V problem could reap big rewards. I now know it does.

Mr Tibbs

Mr Tibbs,

That's very interesting, would you be kind enough elaborate on how you have wired the converter up. I have attached a picture from the spec sheet to help.

Regards,

Mus

Mus,

Input from the supply;

Pins 2&3 negative in. Pins 22&23 positive in.
Again, the input should be taken straight to the converter(s) - DO NOT connect the negative side of the input to the preamp ground. Also, DO NOT use the incoming supply to power any other circuits in the preamp (like the output relay for instance), but power them from the output of a converter via a suitable regulator.

Output from the converter;

Pin 11 negative out. Pin 14 positive out. Site the converter(s) as close to the preamp star 0V point as possible and connect pin 11 to the star 0V point - a short link wire here is what you are after - we are trying to achieve zero impedance between the preamp star point and the converter negative terminal. The positive lead(s) out to the local reg's are not critical.

Pins not used; 9&16 - these are 'common' for when a split rail output is required.

HTH

Mr Tibbs

Other considerations;

Switched mode supplies are relatively noisy! They generate up to 50mV p-p, at the switching frequency (300kHz), and with harmonics. They spew out this noise in all directions. A simple regulated primary supply should stop the noise getting as far as the mains. On the output side, a stage of regulation should keep the noise from potentially de-stabilising the amp stage you are trying to feed. If you are not using a reg after the converter, a simple LC damping filter should be used in addition to the existing Naim RC filter. The type of converter I use has a shielded metal case - I would not risk the plastic covered type.

The local LT1086 reg's I use are connected direct to the individual stages (no RC filter) and with no apparent problems. I have yet to try powering the MC phono boards from the converters - I will report on this as soon as I've tried it. It's early days yet, and I will probably try out some low value inductors here and there to build in a safety margin, even if there are no apparent problems.

Linn (and others) have been using switched mode technology for years. If they can do it, so can we. Time for some music.

More later...

Mr Tibbs

Cheers Mr. Tibbs!

I have been wondering what have you been tinkering with.
Now we know. Very interesting, very interesting..

At least now we can say you have re-built your 102.
Put the superregs back there and we will have another
rave results!

Oz

I've got 50 copper stakes in my garden , each an earth for bits of my HiFi , keep tripping on the wires though , was thinking of just burying the lot , that'll solve earthing problems for good :D

Hi Mr. tibbs,

Indeed fabulous idea!,


The most surprising isue here is that the NAC sounds better with the noisy DC-DC converter.

This means that the low impedance from the power supply to the pre-amp is maybe more important than the supply noise (at least to some level of noise).

At 300kHz the local LM1086 regs. have only ~20db Ripple rejection!, Have you measured the output noise of the 1086 at 300Khz?. I am sure the Super regs here as local regs will be much better since thay have huge advantage V.S the 1086 in the noise figure in high frequencies.



Linn (and others) have been using switched mode technology for years. If they can do it, so can we.
Mr Tibbs

If switched mode supply good for the NAC.. Maybe those Class D amps are
not so bad ... ;)

Cheers,

Avi.

Nice one Mr. Tibbs. I don't suppose this:

http://www.earthcurrents.com/london-live/projects/naimpsu.htm

-influenced your thinking at all..?

I'm not quite sure if the improvement comes for the reason you give - I'm still stewing on this - but the overall principle I have no problem with at all. A dab of LC is probably a good idea, but the much-smaller-box payoff is elegant (says the man with a 6VA preamp supply ;) )

Mr. Tibbs,

I could not locate the 5-2423 converter from the Traco site. How can I find the right one? How much it cost?

Oz

Traco 5-TEN (http://www.tracopower.com/products/ten5.pdf)

Why am I familiar with Tracopower?

Was harbouring thoughts of using Traco smps 24v module (http://www.farnell.com/datasheets/48639.pdf) to feed Superregs. If nothing else, it will make for a cute power supply box.

I could not locate the 5-2423 converter from the Traco site. How can I find the right one? How much it cost?
Oz


http://uk.farnell.com/jsp/endecaSearch/partDetail.jsp?SKU=3842216&N=401

24 GBP.

Regards,

Avi.

The most surprising isue here is that the NAC sounds better with the noisy DC-DC converter.

Avi, Yes, it seems to run counter to the accepted rules, but what you say next, is (IMO) the reason why;

This means that the low impedance from the power supply to the pre-amp is maybe more important than the supply noise (at least to some level of noise).

And it's not even the +Ve rail that matters, it all hinges on having the -Ve of the converter connected right at the preamp star point.

I'm not quite sure if the improvement comes for the reason you give - I'm still stewing on this - but the overall principle I have no problem with at all. A dab of LC is probably a good idea, but the much-smaller-box payoff is elegant (says the man with a 6VA preamp supply )

Martin, ha ha... you want proof - I can understand that ;) In fact, it's easy to demonstrate (at least to myself) why and how this works. Insert about 300mm of wire between the preamp star point and the converter and the difference is easy to hear.

I saw that article you mentioned BTW. What they did was take the (raw) output from a hicap, then fed it through a pair of converters and back into a spare socket in the hicap - so that they could quickly swap between normal hicap and converter outputs. This does nothing at all to improve the 0V system, so they are entirely depending on the DC converters outputting better DC than the reg's of the hicap.

My approach is very different in that (looking at the spec's) I expect the DC converters to be poorer than good reg's, but that the 'ideal' 0V path they allow when placed in the preamp at the 0V point, more than makes up for the shortfall in quality of DC.

I could not locate the 5-2423 converter from the Traco site. How can I find the right one? How much it cost?

Oz, use the link I provided earlier, then select 1-8W DC-DC. Scroll down and select TEN 5. I got mine from RS (part No 293-2886). They will set you back about £50 a pair. Of course, the usual rules apply - I like what this mod does for the music - you might not agree!

Late last night I delved into my John Lee Hooker collection. The house was quiet, everyone was asleep, so the volume had to kept low. I listened for hours (no work today thankfully) and was struck by how good the music was sounding at this low volume. Hooker has a habit of changing his voice and playing from a whisper to a roar in the blink of an eye, and this dynamic content is mostly lost at low volume. Now, the full effect is there at much lower volume than before.

Mr Tibbs

At 300kHz the local LM1086 regs. have only ~20db Ripple rejection!, Have you measured the output noise of the 1086 at 300Khz?. I am sure the Super regs here as local regs will be much better since thay have huge advantage V.S the 1086 in the noise figure in high frequencies.

Yeah, no doubt most of the noise will be getting through at high freq's. But, in an analogue circuit with limited bandwidth, is that really an issue? Some simple LC filtering could substantially reduce the HF noise, so it will be interesting to hear what difference it makes when I try it. I would tend to think this noise would very definitely make itself 'heard' if applied to a digital circuit though.

Super reg's are here on standby - should the need arise. At the minute though, there seems to be no need - this may change when I try powering the phono boards via the converters. To be honest, I hope to keep things as simple as possible. This has the potential (if my ears are hearing correctly) to make very high performance possible without the need for exotic power supplies/regulators (and the know how to make them work). First and foremost comes sound quality - that can't be compromised, but I can't help but smile at the fact that the whole preamp can sound so good with just the addition of a couple of off-the-shelf components and a small external PSU. If we can use some modern technology to our advantage then all the better.

...says the man with a 6VA preamp supply

he he... I like it.

Mr Tibbs

Thanks for everyone for your links and tips!

So, are we expecting your trials for the minimum of PSU's then, next, Mr. Tibbs.

It would be very exciting to hear how it will do it with a wallwart?
Or even with a switching wallwart?

Are we standing on the shore of Ultima Thule now?

Oz

... In fact, it's easy to demonstrate (at least to myself) why and how this works. Insert about 300mm of wire between the preamp star point and the converter and the difference is easy to hear. Well that's all that need be said then... I started drawing out the before and after schematics to have a think about impedances and side effects and quickly ran out of space. Simple demonstrations are good...

he he .. I like it Thought you might:
http://www.acoustica.org.uk/misc/NAR_build/images/11%20DPA%20PSU.jpg

it all hinges on having the -Ve of the converter connected right at the preamp star point.
Don't you get the same effect by having the -ve sense of an SR at the preamp star?

FWIW I think a couple of SR on the output of a Traco or other off the shelf SMPS with some filtering would make a very interesting and very thin (most important) PSU for a Naim pre. There's something extremely inelegant about using way oversized transformers and capacitors.

Paul

Okay Martin,

Tell us more about it all!

How is your power distribution and regulation built for the preamp
when you do use such a PSU sized for an electric toothbrush?

Oz

Oz - don't worry, it's not naimy at all.

It's the offboard supply for my Deltec (DPA50) preamp ; +/- 21v, plus a rail for the muting relay. There are further regulators inside the preamp itself, as well as a lot of fresh air:
http://www.acoustica.org.uk/misc/NAR_build/images/14%20Inside%20the%20Pre.jpg
http://www.acoustica.org.uk/misc/NAR_build/images/16%20SMT%20porn.jpg
Gratuitous SMT porn: the 'opamp' is a 55 x 25mm 4-layer board deposited on a ceramic substrate, and a reputed 500MHz GBW product :)

Yup, fresh air is very important, of course..

Hmm.. Interesting.. Don't understand very much but looks fine. Hmm.

How it sounds?

Oz

So, are we expecting your trials for the minimum of PSU's then, next, Mr. Tibbs.

Yes, actually. Seriously, when the lid of the 102 is finally closed (OK, maybe never finally ), the next obvious step will be to see just how far I can whittle down the external supply. Something like a watch battery, I imagine.

I have just clapped eyes on Martin's DPA power supply. Now that's what I call minimalist :D I love the DPA stuff, they definitely had some very novel and original ideas. I remember reading about this opamp they designed themselves - what an incredible piece of engineering that is - mad, but wonderful at the same time. I think they built something similar as the heart of their power amp. Any pic's of that?

Don't you get the same effect by having the -ve sense of an SR at the preamp star?

Hmm... It could take a thesis to answer that one. In short, SR's are fantastic regulators, but can they create the equivalent of a complete power supply inside the preamp? It would be interesting to hear Andy's view.

There's something extremely inelegant about using way oversized transformers and capacitors.

Couldn't agree more. There must be a better way to crack a nut than just using a bigger and bigger hammer. It would appear (IMHO) there is.

The phono boards are due to get powered 'Traco style' tomorrow AM....

Mr Tibbs

"Originally Posted by Paul R
There's something extremely inelegant about using way oversized transformers and capacitors."


Yes, it is true that Linn for instance have shown us that. How much ever they have got laughs etc. here, at least, their top range amps, the Klimax series can obviously challenge about any amps.

This all came to painful moment as I am just getting ready for a PSU project involving 8 x 50 VA 24V toroids, SR's and all.. Perhaps I will do that anyway just for rehearsal as I am having most of the stuff already. It will feed CDX analog amps, NAC/4 stages and DIYfix.

Well, I can of course, still play with NAC and these marvellous, if a bit pricey cubes if I want to.

Oz

[DPA] definitely had some very novel and original ideas. ... I think they built something similar as the heart of their power amp. Any pic's of that? Well since you asked so nicely:
http://www.acoustica.org.uk/misc/DPA_power1.jpg
800VA transformer for a nominally-50W amp...
http://www.acoustica.org.uk/misc/DPA_power2.jpg
Opamp, driver and output transistors and feedback networks(plural!) for one channel. Feedback is taken from the speaker terminals in a full four-wire Kelvin-sensing arrangement. No output Zobel network in consequence, but only nylon bolts (and anal attention to detail) to hold everything together.

Oz asked:
How it sounds? Well...it doesn't.... ;)


The phono boards are due to get powered 'Traco style' tomorrow AM....Now that'll be interesting. Since the RIAA curve is basically a 500hz lowpass filter any HF noise from the DC : DC converters should be utterly irrelevant - hence I'd expect the benefits to shine :D

I was just thinking that with a DC-DC converter, the single power line from a 140/180 may be sufficent to feed the tracos, and no need for any external PSU box!

Teddy

Mr Tibbs,

I think that there is a way to achieve the same effect you have achieved with the tracos by using a +/- 15V simple power supply. Instead of connecting the 0V to the 102 star point as usually done with the HiCap, connect a local negative regulator (337 or equiv) to the star, and the positive using 1086 to circuit. The 0V of the +/- power supply is only used for the regulators but is not connected to the preamp.

What do you think?

Teddy

IMO the following should work too


--------
30v ---------| 317 |-------- 24 V
-------- |
| R
--------|
R
--------|
| R
-------- |
0 v ---------| 337 |-------- new 0V to 102 star
--------

Teddy

This all came to painful moment as I am just getting ready for a PSU project involving 8 x 50 VA 24V toroids, SR's and all.. Perhaps I will do that anyway just for rehearsal as I am having most of the stuff already. It will feed CDX analog amps, NAC/4 stages and DIYfix.

Oz, carry on with your project, safe in the knowledge that it will perform very well with SR's and separate 0V lines etc. You can try converters further down the road, when at least a few others can confirm or deny the results I'm getting.

Opamp, driver and output transistors and feedback networks(plural!) for one channel. Feedback is taken from the speaker terminals in a full four-wire Kelvin-sensing arrangement. No output Zobel network in consequence, but only nylon bolts (and anal attention to detail) to hold everything together.

Utterly magnificent. Thanks for that.

Now that'll be interesting. Since the RIAA curve is basically a 500hz lowpass filter any HF noise from the DC : DC converters should be utterly irrelevant - hence I'd expect the benefits to shine

Well, they are now in circuit, and with no apparent problems :cool: I haven't put a record on yet... other stuff to do first. Expect a report soon.

I was just thinking that with a DC-DC converter, the single power line from a 140/180 may be sufficent to feed the tracos, and no need for any external PSU box!

No - don't do that! The internal supply in Naim's smaller power amps is grounded to the 0V line, so in effect you would be joining the converter input to output ground, losing the isolation. Any supply used to feed converters should have no electrical contact with the preamp.

I think that there is a way to achieve the same effect you have achieved with the tracos by using a +/- 15V simple power supply. Instead of connecting the 0V to the 102 star point as usually done with the HiCap, connect a local negative regulator (337 or equiv) to the star, and the positive using 1086 to circuit. The 0V of the +/- power supply is only used for the regulators but is not connected to the preamp.

The split rail output is not relevant, I'm not using it. The converter gives complete electrical isolation from the outboard supply - that's the property I needed and that can't be achieved by any application of regulation.

Mr Tibbs

Mr Tibbs,

If I had the negative terminal of my main reservoir cap, say 22000uF, bolted to the star earth, would I have the equivalent of what you are doing?

David
P.S. were you working on this on your honeymoon?

If I had the negative terminal of my main reservoir cap, say 22000uF, bolted to the star earth, would I have the equivalent of what you are doing?

David, Yes, that's what this idea is all about - making the preamp star 0V point 'see' a zero impedance path to the supply. I'm starting to suspect something else is helping things along, because the gain in performance goes beyond what I'd have expected this to bring. It could be that (by luck rather than judgement) this particular type of DC converter, even though it is comparatively noisy, has actually got regulation with very good dynamic performance. I'll need to go and read up a bit on switch mode supplies, but it is possible that the regulation may somehow be 'designed in' rather than simply added on to the output of the converter - giving better performance as a result.

Mr Tibbs

IMO the following should work too


--------
30v ---------| 317 |-------- 24 V
-------- |
| R
--------|
R
--------|
| R
-------- |
0 v ---------| 337 |-------- new 0V to 102 star
--------

Teddy

Mr Tibbs,

I think that you are into something very interesting. I don't have TRACOs to try them, but I was tempted however to try the above design, which I suspected would give similar results. Again, I can't compare, but it gives VERY good results. I've built a single such circuit, connected the 337 output directly to the center of the 102 star, and used the 317 to feed 10 local 1086 regulators (including the phono). One circuit to feed the whole 102!

The results are noticeably better than the previous configuration in which the local regulators were fed by two independent remote TPRs (I'm waiting to get superregs from Andy).

IMHO the improvement comes from the fact that by using a symmetrical supply in which the -V is connected directly to the star, the 0 Volt (which is the -V) is getting the same "treatment" as the +24 Volt. I suspect that the improvement you got from the TRACOs is related to the fact that it is symmetrical, rather than the fact that it has an internal coil.

I suggest that if you have some time, try this solution and compare it to the TRACOs, I suspect you will get similar results, or maybe even better (or maybe not... ;) ).

Cheers, Teddy

Teddy, yeah, I see what you're getting at now. Glad to hear you're trying to solve the same riddle :)

I think I'll be staying with the converters though - I want to end up with a primary supply the size of Martin's DPA - as well as great sound.

The phono boards have been running for 24hrs. The converters now feed a phono board each, as well as the line stages, so the whole preamp is covered by the two converters - one per channel. Before playing any records, I listened to a bunch of CD's, to see if the line performance had dropped any (with the extra load of the phono's). I could hear no change at all, and this is interesting in that the results are different when reg's are used, when any extra load seems to pull the performance down a little.

Playing records: At first, a cold feeling came over me - I thought WTF has happened... There is step change in sound from records. The best way I can describe it is to compare it with spending years watching TV with a set-top aerial, then one day you get the man in to put an aerial on the roof. The picture goes from being slighly fuzzy and ghosted to sharp and vividly clear.

This takes some getting used to though, because the net effect can seem like a reduction in warmth. I guess it's a trade off between warmth and lack of smear. I'll stick with the lack of smear - it really is something to hear so deep into a recording :)

Mr Tibbs

Hi Mr Tibbs
Why not go straight for the top (http://www.vicr.com/products/military/converter_modules/2nd_gen/) ...? :cool:
Yair

Power Factor correction for pre-amps, brilliant!

Now I wonder, which has the lowest output impedance, Superregs or DC-DC?

It would be interesting to know it's output noise (other than switching frequency and harmonics), does it really make no difference to the sound quality if you use a smaller supply, have you tried a Hi-cap v your smaller one to verify this?

Interesting, very interesting.

Yair, Oh no.. that's all we need.. a 'my DC converter is better than your DC converter' race ;)

Now I wonder, which has the lowest output impedance, Superregs or DC-DC? It would be interesting to know it's output noise (other than switching frequency and harmonics), does it really make no difference to the sound quality if you use a smaller supply, have you tried a Hi-cap v your smaller one to verify this?


SR's have lower output impedance, no doubt. Noise from SR's is practically non-existant - compared to a DC converter. A bit like comparing a quiet electric shaver to a chain saw at full throttle.

Does that matter? I'm beginning to wonder.

I'll try the Hi-cap (in standard trim) against a very small and basic supply, but that's down the road a bit. So long as the basic supply can deliver enough current (simple enough), I reckon it will sound exactly the same.

While working my way through records and CD's this afternoon, I've been struck by something else - I think the 'tune' is much better. Strangely, it seems obviously better, but I'm not sure why. Perhaps it is just down to better definition - a clearer presentation.

Mr Tibbs

Tune is better? Now, this is gettin really interesting!

Oz

There is step change in sound from records.

Usually a bad sign IME.

Usually a bad sign IME.

:D Whoa... a touch cynical there, Superman.

Late yesterday I got a spare half hour and rummaged through my parts box. A couple of 370uH inductors were found. These were inserted into the output +Ve of each converter, with a 22uF tant directly across the converter output, and another tant after the inductor, to form a CLC filter. (the inputs of each local 1086 also have a 22uF tant to ground).

The whole thing was left to simmer until I got home from work today. A few records later, I'm almost certain there is no difference with the filters in place. A result then, as I half expected them to actually make the amp sound less good ;)

The next stage (when I get time) will be to turn the test lash-up into a neat and proper finished article - with the obligatory photo shoot, of course :)

Mr Tibbs

Neat.

BTW, can anybody tell me how can I measure an inductor? Can I?
I only have a multi-meter and a capacitance meter in use.

Oz

Mr Tibbs,

That the E-IIIs have the clarity and resolution to show upstream changes is thrilling enough for me. I don't need to understand electronics when you lot are doing such a grand job. As you were, men.

James

Oz,

You can buy LCR meters. I have one to measure the caps and inductors I use for passive XO design.

James

Thanks James,

Please defy LCR?

Oz

L(inductance), C(apacitance), R(esistance).

Though not the cheapest I can really recommend this little widget, at around £70:
http://www.peakelec.co.uk/content/products/atlaslcr.html

Thats a nice bit of kit Martin, I'm gonna get me one of those.

That the E-IIIs have the clarity and resolution to show upstream changes is thrilling enough for me. I don't need to understand electronics when you lot are doing such a grand job. As you were, men.

James,
At the start of the thread I mentioned how good the sound now is at lower volumes and this must be due to improved clarity in the preamp. IME, precious few speaker's have the ability to take advantage of that - most tend to sound pretty lifeless at low volume. So, thanks to the efforts of yourself and Avondale Towers, I have a pair of speakers and a power amp that are superbly transparent from a whisper to a roar.

We don't need to understand loudspeakers, when you are doing such a grand job :)

Mr Tibbs

Mr. Tibbs,

Do you have those Les' Loudspeakers?

Oz

Thanks Martin!

Nice meter, I see. A bit tough investment of course.

Oz

Do you have those Les' Loudspeakers?

Huh? Negatory on that one. I went into my garage for 200 hours, made a lot of noise and dust, and came out with these;

http://www.btinternet.com/~david.stewart37/ergo3pics/5.jpg

James' brainchild, the Ergo III's. A master of the understatement would call them good speakers.

Mr Tibbs

Ahh, you made James's designs?

Quite some furniture they look. Hefty volume. Somewhat Naim-like profile.. Obviously not the structure.

Nice angle you chose for your photo. Shows up the tilted edge of the fascia. This is Tibb Towers, ehh? Cosy! Somebody had the eye for the colours, too! IMHO.

No, I am not asking the freq. range.

3-way? Ported? Cute grille like there was some padding inside?! How did you make that?
Where have you hided your amps? You did have spkr cablings sub floored didn't you?

And the Ergo means that the tweeters' shooting is closely passing your upper dandruff when seated? That's a good balance between standing and sitting listener positions. Well, not so closely, of course, if sitting on the chair in the middle.

Oz

Oz,

The E-IIIs are a 3-way sealed design with a 10-inch Scan-speak woofer in acoustic suspension. It is designed to be heard grill-less, and the reference axis is right between the tweeter and midrange unit. For most people, that's seated ear height. You should ask Mr Tibbs if they do bass tunes properly ...

http://gallery.photo.net/photo/2132057-md.jpg
The only other pair in the world ...

James

Quite nice looking beasts they are, must say James!
Kind of molded fascia? And the weight was?

Your picture lacks a womanly touch - nice curtains would make the
room acoustically better. But this is the same with nearly all the spkr makers.
So nothing to be ashamed there. I understand this is not your anechoic chamber, anyway.

Oz

This thread (http://www.pinkfishmedia.net/forum/showthread.php?t=6727&highlight=ergo) will probably explain all you need to know about James' designs, Oz.

This thread (http://www.pinkfishmedia.net/forum/showthread.php?t=6727&highlight=ergo) will probably explain all you need to know about James' designs, Oz.

Thanks Richard,

I had noticed the James' project but not really read the threads so deeply before. Really stunning stuff! Thanks for noticing!

Oz

Teddy: Theoretically your schematic will work, but in reality, getting your circuit to work may involve more headaches than you would like.

317/337 regulators have an internal 1.25 voltage reference tied to the ADJ pin and the VOut pin, and when you connect a resistor between ADJ and VOut, current of a value corresponding to the 1.25V difference will flow through the resistor. The problem is that there are inevitably differences between individual regulators (and resistors), and your schematic shows a single series connection for the current, including both the 317 and 337. IOW, you have not provided any mechanism to take care of possible differences in the amount of current flowing through the ADJ-VOut resistor for the 317 vs. the ADJ-VOut resistor for the 337, and in reality, there is a very good chance that these current values will NOT be equivalent.

I don't see anything wrong with your basic thinking, but I'd suggest working a bit more on the schematic before building anything.

OTOH, if you are saddled with a set of dissimilar 317 and 337 but want to have them "battle it out", I'd be interested in hearing of your results. :D

hth, jonathan carr

jcarr,

The diagram that I presented works, and the results are much beyond the expectations I had. The 317/337 current differences is not an issue, in fact IIRC I used a 337/1086 pair. The explanation is that the network of three resistors connected to the output sets the current and divides the voltage dropouts between the regulators, each regulator uses the current it needs, which is not necessarily the same. It is possible that better results can be achieved using a center tapped transformer and two resistors, but the current design works marvelously.

I plan to write a more detailed description of this wonder during the weekend, stay tuned...

Teddy

I agree that the results can be quite good, as I have already been doing something like the schematic that you showed, albeit in a manner that avoids any possibilities of current-sharing conflicts that I aluded to in my previous post.

OTOH, your method has the advantage of being a little simpler than mine and with a commensurately lower component count, and since it also works predictably and reliably in the real world, everything would appear to be fine. :)

regards, jonathan carr

Where have you hided your amps? You did have spkr cablings sub floored didn't you?

These days I prefer my hifi heard and not seen.

http://www.btinternet.com/~david.stewart37/LP12/System.jpg

Power amp and power supplies are in a subfloor compartment, under the bottom shelf. The Ergo III's are big, but very easy on the eye. Sonically they are practically invisible though...

The DC converter's are doing something very similar with the 102 - acting like some sort of pre-amp cloaking device. There is an overriding sense that the music is coming direct from the source, with no information being lost or corrupted in any way.

Mr Tibbs

Mr Tibbs,

Is it a CDX below the 102? Are you using an XPS?

I just built myself an XPS clone and it really improves the sound, but after reading this thread I thought of a much simpler way to do it. Naim is using inside the CDX an internal transformer that produces a too low voltage to power an XPS and the CDX, and it doesn't have enough secondaries, but with DC-DC converters any voltage can be generated. It should be possible to build a small DC-DC based box connected to, and powered from the burnday plug, which will generate the +/-22, +/- 10 and 2x15 that the CDX needs in order to work at it's best, and feed it back to the CDX through the same plug. What do you think?

Teddy

Very interesting indeed Teddy and could be actual to me right now.

But should it be inside the CDX to make it as close and direct connection to the common ground as possible?

Or is it different thing here than in the NAC?

Or... can it be made here without disturbing the possible newbuilt central ground in the NAC or would they argue with each other?

Maybe I am out like a snowman about this virtually built new zero...?

How many DC/DC converters should be needed? Getting expensive..
But of course it is costing quite much by traditional way, too.

I would like to try this out - a mini sized, lightweight,
hi-tech "XPSXS" - sounds sexy.

Oz

I would do it outside the CDX, just for the sake of not touching an expensive Naim box. But since it can be implemented in a really small box, I would do it using a short cable hanging on the back of the CDX.

I would use at the maximum three converters. Melcher does one that can generate +/- 25V, then a traco for the +/- 10V, and another traco for the 2*15V (the last one may be avoided if you are looking for economies). The whole thing should fit in a very small box, probably less then 10x5x5 cm.

I would use 1086/337 for regulators, or TPRs.

I didn't do any of the above (yet), but that's what "I would", have I read this thread before investing in transformers and capacitors... ;)

Teddy

I use a CDPS and new type Burndy with my CDX - all unmodified and sounding wonderful :)

TBH, I don't think DC converters and using the internal supply would make a better supply for the CDX than the existing internal supply - never mind a CDPS or XPS. For a start, part of the gain of using an outboard supply on the CDX is not having any live transformer in the box. Also, while the noise generated by DC converters seems to have no negative effect on analogue stages, this will not hold true for digital circuits, where it would almost certainly be inferior.

I used the DC converters in my 102 to solve the one problem that is peculiar to any preamp that uses single rail circuitry and an outboard supply. The same does not apply to CD players, where the analogue circuitry is not single rail and the digital circuitry needs very low noise.

It might be interesting to build an external switch mode supply for a CDX (or CDS), paying a lot of attention to filtering out noise etc. But you'd have a hell of a job making it work as well as a good linear supply like the CDPS or XPS.

Sorry ;)

Mr Tibbs

edit; Please do go ahead and try it though :)

Yes, I agree it wouldn't be better than a CDX, just smaller and cheaper... If it gives the same or close to same results, it might be good enough

You may probably be right wrt the digital circuits, I would thus focus on the +/- 22V, which are used for the analogue circuitry. I don't know what the +/- 10v are used for, but the +15 V (at least one of them) is/are for the motor and leds, so it doesn't matter much anyhow.

BTW, it's easy to check whether the local transformer has a negative effect on the CDX by powering it while the CDX is powered from the XPS/CDPS, my guess is that if there is an effect it would be minor, it just a guess though...

Teddy

oops, I meant wouldn't be better than an XPS...

A decent amount of time (and music) has now passed since going all switch mode with the 102. Earlier I mentioned that I seem to be getting better 'tune' from the music. Now, after having played many albums, I'm certain that something quite profound has happened.

Any previous mod's using ever more exotic power supplies have all been positive in that they had the effect of decreasing smear and bringing out more detail. The difference this time is not so much an impression of more detail (which there is), but a very definite improvement in how 'in tune' everything sounds. It makes voices and instruments (of all types) take on a far more real and natural sound. It's pretty obvious too - not at all 'golden ear' stuff. For the first time, I can see why Linn are so keen on the tune dem as a means of choosing HiFi.

In future, anything I modify will have to further improve the 'tune', or it won't be worth doing.

I can see why people talk with scorn about systems that throw out an enormous amount of detail, but don't sound very 'musical'. I guess they are saying the system has no 'tune'.

Mr Tibbs

That is called "heureka!", Mr Tibbs! Congratz! :)

We have got another enlightened listener here!!
It's all about the music. Not really about details or space.
But there's nothing to be ignored about them if the music side is okay.

Oz

Mr Tibbs,

Very interesting... It looks like someone else has been here before... A long time before ;-)

I wonder why he has not posted a comment here?

http://www.earthcurrents.com/london-live/projects/naimpsu.htm

How many DC-DC converters would I need? I have a 102.

Yeah but it's a different thingie, John.

Read this thread backwards and you will find a discussion earlier about it all.

Oz

Found it... slipped through the net.

Mr Tibbs any chance of a picture to show the install next time the lid is off?

Very interesting... It looks like someone else has been here before... A long time before ;-)

Hmm... no no no no, NO! ;)

As Oz has said, check back a bit for more info.

How many DC-DC converters would I need? I have a 102.

I've used two. Each one is dedicated to powering four 1086 local reg's per channel. (phono/filter/buffer/gain).

Have good read through the thread and the whole idea behind this should become clear. The actual practical application is fairly straightforward, but feel free to ask if anything doesn't make sense.

When I get some time I'll be making up a couple of small PCB's. Each will have a DC converter and four 1086 reg's fitted, to make a neat and compact finished job. Pic's to follow.

Mr Tibbs

Mr Tibbs

Have been following the thread and wondered if you could maybe provide some advice...

Have just built 2 Lawtronics SLA 1500 battery chargers (recommended by Andy Weekes) and Les` TPR boards into power supplies to replace a Hiclone - and the results are much better than I`d hoped for. Truly a great, cheap PS. The TPRs feed reg boards made up of 4 X 1086`s in both the preamp and x/o - wondered if introducing the DC-DC converters you mentioned between the TPRs and the internal reg boards is the correct procedure. Can/should these be used w/ the output directly to the internal reg boards? If so, since the pre & x/o need 24V rails each, which output pins of the converters are used,( or is just one converter pin used and the power rails jumpered) ?

Thanks
billinjapan

The TPRs feed reg boards made up of 4 X 1086`s in both the preamp and x/o - wondered if introducing the DC-DC converters you mentioned between the TPRs and the internal reg boards is the correct procedure. Can/should these

In short, yes. The idea is to get the -V output of the converter(s) as close as possible to the 0V point in preamp or XO (I see no reason why they should not work wonders in a Naim XO, BTW). It is this short 0V link that seems to be critical in releasing a new level of performance from these little single rail circuits that are universal to Naim preamps and active XO's. In the few tests I've tried so far, the quality of outboard supply makes little or no difference when DC converters are used, which is a great bonus.

Can/should these be used w/ the output directly to the internal reg boards? If so, since the pre & x/o need 24V rails each, which output pins of the converters are used,( or is just one converter pin used and the power rails jumpered) ?

You can take the converter outputs direct to the local reg's. I have tested with a cap/inductor/cap on the output of the converters (see earlier post) but can detect no difference in sound - though it's probably still wise to include this. Use an inductor on the +V ouput rail only, not the -V. The cap's go across the output, one before and one after the inductor. The 0V reference for the internal reg's should be taken to the preamp 0V point as normal. If the local reg's are sited away from the converters, make sure you place a small cap across the input of each local 1086 (a 22uF tant is good here). The converter output pins are; -V pin 11. +V pin 14. Again, there is more info on this earlier in the thread.

Try two converters in the preamp first, before starting in the XO. One simple outboard supply (like the type you have) will feed both converters. The input from the external supply should connect straight to the converters; -V pins 2&3. +V pins 22&23. If you have a 102, you should power the control circuitry with a separate linear supply.

HTH

Mr Tibbs

BTW,
Do a dry run by hooking up the converters and local reg's away from the preamp, on the bench. You can connect up some dummy loads then let the thing soak for a while to make sure everything is behaving nicely.

Mr Tibbs

The one rail original SNAPS becomes to renewed value, I see.

Perhaps we should rename it too. How about STIBBS?

Let's start looking for cheap STIBBSIES! :p

Oz

In short, yes. The idea is to get the -V output of the converter(s) as close as possible to the 0V point in preamp

I don't know if the same applies for the "nirvana" DC/DC converter, but when I connected the "-" of the "earth regulator" that powered the phono boards to the star point of the 102 I got some hum, which was resolved when I connected it directly to phono board ground. My conclusion is that if only part of the preamp is powered by the regulator, connect the "-" as close as possible to the ground of this part.

I don't know if the same applies for the "nirvana" DC/DC converter, but when I connected the "-" of the "earth regulator" that powered the phono boards to the star point of the 102 I got some hum, which was resolved when I connected it directly to phono board ground.

Sounds like you had some kind of inductive loop thing going on there. No problems to report at this end (so far...)

In the meantime... a new PCB is born :)

The DC converter goes on the RHS of the PCB. To the left, will be four 1086's and associated components. Two boards will be needed to cover both channels. Quite compact, so would easily fit in a shoe box pre...

http://www.btinternet.com/~david.stewart37/102pics/DC-PCB.jpg

Mr Tibbs

...you have a clean machine? DC: DC shows you a cloud-free galaxy...?

Mr Tibbs, good to see things are going so well that you are making it permanent with a PCB, how do you make your PCBs if you don't mind me asking?

Looks quite intricate!

...you have a clean machine? DC: DC shows you a cloud-free galaxy...?

teehee :)

Mr Tibbs, good to see things are going so well that you are making it permanent with a PCB, how do you make your PCBs if you don't mind me asking?

Manually making PCB's is a right PITA! (not really, but it is a bit time consuming) First, the golden rule; make sure the layout is well thought out, with actual component sizes accounted for.

Basically, the process is simple. You mask off the areas of copper that you want to keep, then put the board into a small plastic bath of ferric chloride solution. The solution dissolves the un-masked copper, leaving the masked areas intact. The masking can be done with special transfers, or masking pen and a steady hand.

After that, you drill all the holes, clean the copper with wire wool, then finish off by tinning the copper with solder. It is possible to make a fairly pro looking board by this simple method.

'Stripboard' is extremely tacky looking and should not be used for anything other than a quick test ;)

Mr Tibbs

Yes, genius devices deserve more than stripboard, I'd get carried away with the etching though, I mean, electronic devices would look good with a picture around them ;) Mondrian anyone?

On the +Ve side, as far as regulation goes, the converters will not be as good as say SR's, but there is nothing to stop you using SR's along with the DC convertors.
Mr Tibbs

I'm intrigued enough to try this having just received my allotment of Andy's boards.

How does one connect the DC converter to a Superreg downstream if the converter's -ve is already connected to the preamp star 0v?

How does one connect the DC converter to a Superreg downstream if the converter's -ve is already connected to the preamp star 0v?

The DC converters are there to isolate the external supply, but otherwise make no difference to how you connect up any following regulation. You connect the SR ground to the preamp 0V point as normal.

Mr Tibbs

The boards are fitted and burning in!

To the right of the converters, you can see two 100uF cap's and beyond those the 470uH inductor. These form the CLC filter on the output of the converters. After that comes the bank of four LT1086s. The row of Tants in front of those are 22uF - used on the output and adjust pins of each regulator. In among the tants you can just about see the two resistors per reg. A bit fiddly to build up, but the boards had to be kept small enough to fit on either side of the preamp 0V point.

http://www.btinternet.com/~david.stewart37/102pics/Traco1.jpg

http://www.btinternet.com/~david.stewart37/102pics/Traco2.jpg

Mr Tibbs

Hi Mr Tibbs,

It looks really nice, congratulations.

IIRC you used to have small 1086 regulators hidden under the main PCB, and close to the circuits that consume them (which is also what I've done). What made you change the layout, i.e. why not have central PCBs for the DC/DC (which can also go underground) to power the small 1086 PCBs?

I've noticed that you kept the original 47u capacitors of the main board. In this case do you really need the output 22uF tants? I omitted them, with no problems so far.

Also, have you considered using TPRs instead of simple 1086? I'm using them (until I'll get the SRs), with good results. Currently I have six TPRs + two ground regulators, everything hidden under the main PCB, the TPRs for the phono board had to remain visible on top of the PCB. Having them under the main PCB was your idea... ;)

Teddy

IIRC you used to have small 1086 regulators hidden under the main PCB, and close to the circuits that consume them (which is also what I've done). What made you change the layout, i.e. why not have central PCBs for the DC/DC (which can also go underground) to power the small 1086 PCBs?

Teddy,
Because as you mention, it looks nice :D

Seriously, the original 1086's went under the main board because six separate pcb's plus all the wiring can look decidedly Heath Robinson when in full view. There is no difference in performance (as far as I can tell) by having some wiring between them and the circuits they feed.

Also I wanted to put together something that is a compact and complete solution to what I believe are the two major factors that determine the outright performance of the circuits in these preamps. Certainly the regulation on the +V side could be made better than the 1086s allow, but not without adding a bunch of SR's which makes for a lot of extra complexity.

I've noticed that you kept the original 47u capacitors of the main board. In this case do you really need the output 22uF tants? I omitted them, with no problems so far.

The 22uF tants are needed to maintain stability of the reg's - the 47uF cap's may not be able to do that (tants are better here) - especially when distant from the 47uF cap's.

Also, have you considered using TPRs instead of simple 1086?

My ears tell me the 'simple' 1086's are not holding the performance back ;) - they are very good regulators.

Mr Tibbs

I've also found the 1086 to be far superior to the more used, was it 317?

Oz

I'm using two 1086 for the TPRs (home made TPRs). I started by having simple 1086, then when I switched to these TPRs the improvement was definitely noticeable. It was before I added the ground regulator, maybe now the effect will not be the same.

Teddy

True. Maybe.

Oz

Update:

I've now tried out a couple of alternative primary supplies, leaving each in for a few days to give a good feel for any change.

Interestingly, the results do change with changes in the primary supply, but much less so than is normally the case with 'standard' regulation. I started off by feeding the two converters with a single rail supply that is close in spec to a Snaps. As already posted, the results are excellent- comfortably better in all areas than a Hicap with six SR's.

Next up, came a ratty wall-wart that was just about able to deliver the 8W that the two converters demand. The sound took a bit of a nosedive, with the bass definitely not as well defined, and a certain loss of clarity in the mid-band.

Lastly, after the plain 317 reg's were re-installed in the Hicap, I hooked a single rail of it up to the converters. This is giving the best results yet, with the preamp sending out a signal with a real 'master tape' feel to it. The other half of the Hicap is being used to power the preamp control circuitry, but I suppose it might be worth putting the wall-wart back on control circuit duties, to free up the second Hicap supply. This would give one Hicap supply per DC converter.

That said, I could very happily live with the sound I'm getting now. It's obvious that the music signal is passing through the preamp with the absolute minimum of degradation ñ which is a pretty tall order for a complex bandwidth limiting design.

Mr Tibbs

Hello Mr Tibbs, there are two sides to this, the downer is the power supply is still important, not much suprise there really, your invention would have been the first to be immune to mains variation otherwise, the upside I suspect maybe that any improvements here on in are maximised to the full which would bode well for any more money spent on power supply, also, do you think the larger converters would have any worthwhile improvements?


Congratulations by the way on the results.

there are two sides to this, the downer is the power supply is still important, not much suprise there really, your invention would have been the first to be immune to mains variation otherwise,

Well, it certainly would have been nice if the DC converters had proved completely immune to the quality of upstream supply. They are (I would guess) about equal in this respect to SR's, which is pretty damn impressive anyway :) The original goal was to rid the preamp of the performance-limiting 0V returns, with any reduction in the need for primary PS quality being a nice side benefit.

also, do you think the larger converters would have any worthwhile improvements?

DC converters are a bit weird in that they generally perform better (less noise) if run at or near their design limit. A 2A converter may prove to be no better (possibly worse) than a 0.2A converter when asked to deliver 150mA. On the other hand, the 2A converter might be more immune to the quality of outboard supply. It would take a lot of trial and error to get a definitive answer to that one. I'm not bothered TBH - if it ain't broke don't fix it and all that.

Thanks :)

Mr Tibbs

Mr T...

my Traco units arrived from farnell today....




Mus,

Input from the supply;

Pins 2&3 negative in. Pins 22&23 positive in.

Mr Tibbs


Why both 2&3 and 22&23? rather than just 2&22?

Mr T... my Traco units arrived from farnell today....

Oh my... gawd...

The moment of truth has arrived... a brave soul has laid down his plastic :o

Why both 2&3 and 22&23? rather than just 2&22?

Good question, I dunno. I followed the manufacturers instructions and they worked just fine (well, a bit better than just fine ).

Enjoy!

Mr Tibbs

Lastly, after the plain 317 reg's were re-installed in the Hicap, I hooked a single rail of it up to the converters. This is giving the best results yet, with the preamp sending out a signal with a real 'master tape' feel to it. The other half of the Hicap is being used to power the preamp control circuitry, but I suppose it might be worth putting the wall-wart back on control circuit duties, to free up the second Hicap supply. This would give one Hicap supply per DC converter.

I had to give this a go - in the interests of those interested, if nothing else.

With each DC converter powered by a separate half of the Hicap (wall wart on control duties), I've gone back over a few familiar records and CD's. In short, if there is any further improvement, it's not worth getting excited about. It would appear a platuea is reached when a decent single primary supply is used. So, the DC converters do need something better than a wall wart, but otherwise are not terribly fussy WRT the primary supply.

It could be down to the fact that they generate noise on the supply, and that a better (lower impedance) primary supply will be more effective at damping this noise. A way around this might be to place an LC filter at the input of the converters - an experiment for another day, perhaps.

Mr Tibbs

Thanks for doing the experiment Mr Tibbs, gives an idea where to go next (I haven't even started these mods yet, in a months time) have you thought about strapping the rectifier together, it makes a large improvement through I imagine impedance lowering, simple and free!

Mark,
Yeah, I like free improvements just as much as anyone else :)

I'm going to take a step back though, because I think the single hicap supply to the converters is giving 99% of what they've got. This means I can use the other 24V to power the control stuff, doing away with the wall-wart.

I'm very keen to hear what Jo Sharp thinks of the converters, and also how they respond to changes in primary supply.

On a wider note;

It's exciting times for DIY@PFM. There seem to be plenty of hardy souls beavering away at their gear - preamps in particular, with some novel approaches to breaking through the 'glass wall' performance limit set by the initial design. I'm constantly amazed at how much the sound can be improved by changes made in the preamp alone!

The sharing of this information for the benefit of all is what makes it so worthwhile :)

Mr Tibbs

I'm constantly amazed at how much the sound can be improved by changes made in the preamp alone!
Mr Tibbs

Cannot but second this phrase! Especially If we include the preamps's PSU.

Oz

Cannot but second this phrase! Especially If we include the preamps's PSU.

Goes without saying that when I say preamp, I mean preamp and PSU.

(But I'll say it anyway)

Mr Tibbs

Keep blazing the trail Mr Tibbs and thanks for sharing.

Goes without saying that when I say preamp, I mean preamp and PSU.

(But I'll say it anyway)

Mr Tibbs


Yup,

And actually it has become more and more that we put the PSU partly into the preamp..

Thanks for sharing from my part, too, Mr Tibbs!

Oz

The Tom Evans Vibe Preamp has got a lot of stunning reviews from the press. More so than the fake type of praise normally found for advert space buying manufacturers, you can really tell the reviewers think the Vibe is a great product.

One of the main aces up Tom Evans sleeve has been this 'Lithos' power regulation that supposedly contributes to the 'stunning dynamics and inky black backround' e.t.c

It all sounds like a whole heap of hype, none the less an unusual preamp technology that not many people use is always interesting and im open to the idea.

6 Moons have just posted a preview of the the Vibe.

http://www.6moons.com/audioreviews/tomevans2/vibe.html

They also posted some internal shots of the preamp including this famed Lithos power regulation.

http://www.6moons.com/audioreviews/tomevans2/hero_lithos.jpg

http://www.6moons.com/audioreviews/tomevans2/strip_board.jpg

Lo and behold the Lithos board looks very similar to Mr Tibbs DC to DC converter. Prehaps you have cracked the secret Mr Tibbs, and the Lithos is just a matured version of what you are working on now?

Lo and behold the Lithos board looks very similar to Mr Tibbs DC to DC converter. Prehaps you have cracked the secret Mr Tibbs, and the Lithos is just a matured version of what you are working on now?

I don't see any SMPS on there though. Probably just looks a bit similar because of the bunch of reg's and tant's.

Mr Tibbs

Looks more like sregs with tantalums.
Intel inside instead of Analog Devices?
(The Lithos logo)

Looks more like sregs with tantalums.

Yeah. Let Andy crunch this for awhile.

Oz

Mark,
Yeah, I like free improvements just as much as anyone else :)

I'm very keen to hear what Jo Sharp thinks of the converters, and also how they respond to changes in primary supply.

Mr Tibbs

Got them fitted this morning. The connections to the pre-amp 0V point are via a 2cm 17A cable ...so fairly close.

Output to 6 SRs....

On switch on not impressed....bass and mid-range seemed to have hopped out of the window and were hiding in the garden.

After 8 hours of warm up a bit better, but bass still rather pedestrian...

Have checked all connections and voltages...all seems OK, so I will leave it another 12 hours before listening again.

On switch on not impressed....bass and mid-range seemed to have hopped out of the window and were hiding in the garden.

Jo, that's the exact opposite to the results I'm getting -IE The (blindingly obvious) best kick-ass bass I've ever heard at home, with a very vivid and open midrange. I kid you not!

Output to 6 SRs....

That could well be the reason - my converters output to eight 1086's*. It could be that the SR's just don't like being fed by SMPS. What output voltage are you running the SR's at? 24V out/ 30V in might be cutting it a bit fine, if that's what you're running. Also, have you used any form of filter between the converters and the SR's? This may be necessary for use with them. Also, is the 0V of your primary supply for the converters totally independant of the preamp 0V system? It must be to get the benefit of the converters.

so I will leave it another 12 hours before listening again.

There's no point - if it didn't work from the word go then it won't improve. The results I got were instant, with only limited 'smoothing out' over a couple of days. Sorry this (so far) hasn't worked out for you, but you might need to try this exactly as I have with local 1086's to witness the magic of these things. I understand if you feel that would be a backward step from local SR's. Like I said at the beginning, a leap of faith is needed to realise the potential of these things.

Mr Tibbs




*As you may remember, I could not run my six SR's as local reg's in the 102 as I ran into problems with HF oscillation, making itself heard as kind of muted (but edgy and harsh) hiss from the tweeters - not the normal dull hiss the amp generates.

Also, is the 0V of your primary supply for the converters totally independant of the preamp 0V system? It must be to get the benefit of the converters.

An easy way to test for this is to connect a Voltmeter between the negative in and positive out of a converter - you should get no reading.

My 102 mod's in order of best sound (not in tested order);

Bog standard 102/standard hicap

102 with local 1086's/standard hicap

102 with local 1086's/hicap with two SR's

102 with local 1086's/hicap with six SR's

102 with local SR's/standard hicap (with raised OP V) - would have stopped there, but for instability problem.

102 with local 1086's/hicap with six SR's and split 0V

102 with local 1086's/DC-DC converters/standard hicap single rail to converters.

HTH.

Mr Tibbs

102 with local 1086's/DC-DC converters/standard hicap single rail to converters.

Mr Tibbs,

std hicap to mean 24v feeds letting the converters bringing them up to 30?

std hicap to mean 24v feeds letting the converters bringing them up to 30?

Yes, that's correct. The model of converter I use will run with between 18V and 36V on the input.

Mr Tibbs

102 with local 1086's/hicap with six SR's



Mr Tibbs,

Can you elaborate on that? How and where did you use the SRs and the 1086s (i.e. which board gets which regulator)? I'm having a similar dillema (see my other thread about SR allocation)

Thanks, Teddy

Can you elaborate on that? How and where did you use the SRs and the 1086s (i.e. which board gets which regulator)? I'm having a similar dillema (see my other thread about SR allocation)

Teddy, Originally I used the six SR's/local 1086's to feed only the line stages, with a totally separate supply to handle the phono boards (and yet another supply for the control stuff). It's a good idea to go all out on the line stages, as they have a huge impact on CD replay, but also on the signal leaving the phono boards too.

If you're running a 102, I'd advise you to power your tape buffers (and front panel logo) from the control supply. This leaves the main supply to handle the stuff that matters - the line stage circuitry.

HTH

Mr Tibbs

Mr Tibbs,

after another 12 hours of warm up things are starting to sing again.
Good strong bass drive and a little more detail in the higher frequencies. It is not a big difference from what was there before...but it is worth waiting a few more days to see if things get even better.

As my pre and SNAXO have always been a little slow to come on song after a power-down, I'm not surprised at the experience so far. One problem though....if I adjust the volume or balance using the remote, when the movement has stopped I get a 1-2 second swooshing noise from the speakers...doesn't happen if I adjust by hand so there seems to be some noise being dumped from the motor circuits that wsn't there before fitting the Tracos.

..after another 12 hours of warm up things are starting to sing again. As my pre and SNAXO have always been a little slow to come on song after a power-down, I'm not surprised at the experience so far

Very glad to hear that things are starting to shape up. Earlier I said that my own worked great from the beginning, but I'd forgotten that it had the benefit of a soak on the bench for a good few hours before a note was played.

It is not a big difference from what was there before...but it is worth waiting a few more days to see if things get even better

Let's see what happens over the next 24 hours or so. If you get the same result as me, the overriding impression should be that you're listening to directly to the source.

if I adjust the volume or balance using the remote, when the movement has stopped I get a 1-2 second swooshing noise from the speakers

Hmm... strange that the noise comes after the motor has stopped. That doesn't seem to be happening to mine TBH.

Mr Tibbs

Mr Tibbs,

When you say SR/ local 1086, do you mean that for each SR you have a local 1086 after the SR? Some people tell me that having a 1086 after the SR will negate the qualities of the SR (impedance etc). Have you compared?

Teddy

When you say SR/ local 1086, do you mean that for each SR you have a local 1086 after the SR? Some people tell me that having a 1086 after the SR will negate the qualities of the SR (impedance etc). Have you compared?

You obviously haven't read posts 105 & 106 of this thread, Teddy ;)

Mr Tibbs

Also, is the 0V of your primary supply for the converters totally independant of the preamp 0V system? It must be to get the benefit of the converters.

An easy way to test for this is to connect a Voltmeter between the negative in and positive out of a converter - you should get no reading.


HTH.

Mr Tibbs

Checked this last night...reads 0.2V..so looks OK.


Next step will be to drop the output voltages of the SRs to give more headroom...they are running at either 24.7 or 25.3 V at present. What a pain digging them out again, but it will allow me to put a better 0V wire on them as well.

Checked this last night...reads 0.2V..so looks OK.

Yep, that's fine.

Next step will be to drop the output voltages of the SRs to give more headroom...they are running at either 24.7 or 25.3 V at present. What a pain digging them out again, but it will allow me to put a better 0V wire on them as well.

Set your SR's to output around 23V, this will give a healthy 7V for the SR's to play with, giving some room for the small drop across an inductor if you include one between the converters and SR's. A CLC filter of something like 100uF/100uH/100uF would usefully lower hf noise from the converters. The LT1086's seem to be fine when tested without the CLC, but the SR's may not be so happy...

Hopefully, sorting out the above should see some real gains in the performance of your pre.

Mr Tibbs

Mr Tibbs,

have changed the regs to between 23.9V and 24.2 V output now...don't have the right resistors to go down to 23V. And things seem to have improved even on start up. I think you may have found something rather interesting with this one!! I'll let it warm for 24 hrs and report back.

Haven't got any filtering between the tracos and the SRs...might have a go at that one next week.

Mr Tibbs,

I am about to try your recipe and like Jo will be using Sregs.
Can you dumb down the CLC filter bit for me?
Are the cap/inductor/cap inserted in series between Traco and SReg +ve?

TIA

Mr Tibbs,
I currently have a std 102 powered by a std Hicap and a SNAXO powered by another std Hicap. I have 4 SR but have not yet wired them up was planning to add these to the Hicaps... This thread is extremely interesting as this may not be necessary and I could maybe sell the SR to fund these little DC-DC thingyies... Is there a circuit diagram for the install available?

Am I correct:
Would I only need one Hicap? a DC rail for 102 and SNAXO?
Are the SR redundant? (maybe for the prefix)

I did buy the 102 with the view to 'Tibbs-ing' it up so this is ok...

John.
I am looking to buy a couple of ready built s/r's for a ps I intend to build.Drop me a pm if you do decide to sell a pair.

I'd love to try this on my 72, but would explicit details of what to connect to what (say for the LT1086 config that you have, Mr. Tibbs) as so far my DIYing has been limited to drop-in replacements. So if someone has the time and patience, would be greatly appreciated.

Thanks,

Jon

Here is the basic circuit showing a DC converter, supply input, supply output to local reg's, and CLC filter. When I get some time I'll do another to show the circuit for 1086's. Don't forget, the primary supply input to the converters MUST go direct to the converters and have no other connection to the preamp. Choose a power inductor that is rated at 300mA or greater.

http://www.btinternet.com/~david.stewart37/102pics/Traco.JPG

Mr Tibbs

Am I correct:Would I only need one Hicap? a DC rail for 102 and SNAXO? Are the SR redundant? (maybe for the prefix)

Yes, one hicap would easily be able to cover the needs of both preamp and snaxo signal circuits. Some sort of separate supply would still be needed for the preamp control circuits. SR's would still be a great choice for the prefix.

So if someone has the time and patience, would be greatly appreciated.

Hopefully a couple of basic circuit diagrams will clear up any uncertainty.

I think you may have found something rather interesting with this one!!

Seems like you're starting to hear the effects of this mod :)

Let's take our time here and see how things pan out for Jo, with the converters/local SR's - it's starting to look promising, but it's early days.

Mr Tibbs

OK, so here is your common or garden LT1086 three terminal reg all dressed up and ready to go down t' local. In place of these you could use some of Les's nifty TPR's, or you could get really carried away and use ALW SR's. You pays yer money, you makes your choice, YMMV.

We await Jo's full and frank report.

http://www.btinternet.com/~david.stewart37/102pics/1086.JPG

Mr Tibbs

Mr Tibbs

Traco dc converters arrived today - am going to install them in my 42(.5) this eve.

One quick question - can the 2 input pins on the converter share a single 24V lead, (both pins conected to the same lead, thus tied) OR should each input pin be connected individually to its own 24V lead? Likewise the 2 OV input pins?

Will report back and send pics when I can find the camera charger....

Cheers
Bill

OK - things are working. 28.5 V in, 29.9V out, all the gear is dead cold, switched off all day in a snow-bound house, so no sonic impressions yet -

however, when using the cd/dac, there is static and very quiet popping - not volume control dependant - cleaned it already...sounds like static electricty discharging - though the tweeters.analog through the dac is fine, as is phono.

anyone au fait w/dc-dc and digital devils?

however, when using the cd/dac, there is static and very quiet popping - not volume control dependant - cleaned it already...sounds like static electricty discharging - though the tweeters.analog through the dac is fine, as is phono.

OK, some stuff to try;

Disconnect sources from preamp inputs to see if problem persists. After that, check if all connections are as per instructions - especially check to make sure 0V output of Traco's is isolated from 0V input. You do this by placing a Voltmeter across the Traco 0V input and 30V output - you should get no reading.

What is your primary supply? What local reg's are you using? Give as much info as you can about how everthing is connected up - photo's would help a lot. I'm sure this can be sorted.

Mr Tibbs

PS Re-reading your post, is the problem only when the DAC is used? What CD player/DAC are you using?

Mr Tibbs

Thanks - have already disconnected, checked and reattached cables to the preamp.
Will sort out digital cables and components this eve. With the other components off but connected to the preamp and the preamp volume at about 11:00, there is a faint whine I associate w/digital gear that was not there before. Will check the voltage tonight, and check for the whine w/ digital gear disconnected.

The "static/popping" problem apears to be caused by a cheap Pioneer dvd player, which I`m using because my CEC transport is in for service. Dac is Polyfusion 800. The "static/popping" doesn`t occur until the transport begins spinning the disk. It`s a cheap, noisy mechanism to start with.

Power supply is a Lawtronics SLA1500 battery charger w/ an Avondale TPR module feeding the tracos, into a bank of 4 1086`s.(Same ps for the naxo 2X4, but w/o tracos) The OV from the PS is attached to each of the tracos, and the tracos` OV outs to the preamp OV point, by about an inch of copper wire. There is no OV connection from the PS to the preamp except via the tracos.

Thanks for the help - will post back w/pics and progress.

Bill

With the other components off but connected to the preamp and the preamp volume at about 11:00, there is a faint whine I associate w/digital gear that was not there before. Will check the voltage tonight, and check for the whine w/ digital gear disconnected

A couple of thoughts;
DC converters are noisy, and when I first fired up my 102 with them in, I almost expected to have to shut the thing down right away. The amazing thing is, I reckon the noise floor of the pre has actually dropped a little - especially noticable when using the phono input. At full volume on any line input, there is no hint of any extra noise leaking in from the Traco's.

When I first fitted them for testing, they were temporarily fixed directly to the preamp PCB with double sided tape - upside down. The idea being to have the metal case acting as a shield (the pin side of the converter is not shielded). The PCB I fitted them to is double sided copper, to give some shielding when the converters are fitted right side up.

Power supply is a Lawtronics SLA1500 battery charger w/ an Avondale TPR module feeding the tracos, into a bank of 4 1086`s.(Same ps for the naxo 2X4, but w/o tracos) The OV from the PS is attached to each of the tracos, and the tracos` OV outs to the preamp OV point, by about an inch of copper wire. There is no OV connection from the PS to the preamp except via the tracos.

Looks good.

HTH

Mr Tibbs

Traced the problem to a Monarchy DIP de-jitter box. It has been removed. There is still a scrim of noise riding the signal line at about 11:00, pitch has changed. Voltage
measures as you indicate it should - will recheck the solder joints and OV point tomorrow.

Things are clearly better now w/ warm gear, the noise floor has dropped, details that were masked before emerge more clearly, the interaction among musicians is easier to follow, and a more accurate sense of recording space is evident. Overall presentation is more immediate and lifelike. This from a crap DVD player. LPs tomorrow, and another week until my CEC comes back from the shop. Will keep everyone posted and post pics soon.

Many thanks, Mr T, for your insight and assistance - if things continue to improve this mod is going to be the best so far. Do it now, guys, you won`t regret it.

There is still a scrim of noise riding the signal line at about 11:00, pitch has changed.

Bill, I'm sure we can banish that remaining noise. I'll know better what to advise when I see some photo's of the install.

Overall presentation is more immediate and lifelike.

Yes, that's very much how I would describe the effect of the converters.

Prior to the Traco's going into my 102, I felt I was hearing an already very convincing musical performance, but the converters seem to have moved the goalposts a bit. The one downside (so far) is the price you pay for hearing exactly what the source is pumping out, warts and all. A second rate source is going to sound decidedly second rate, and even if the source is good, the recording itself is laid bare. A few records and CD's I'd previously thought were well recorded have turned out to have a few flaws here and there. It's pretty easy to enjoy the more natural and insightful reproduction though, so the odd flaw can be ignored.

LPs tomorrow, and another week until my CEC comes back from the shop

My pleasure, Bill. Looking forward to reading how you get on :)

Mr Tibbs

Carefully, til' Bub, Fox et al sees this, Mr. Tibbs!

They WANT to listen to the power plants' coal brists brushing on the generator anchor anodes & the bubbles of nuclear water boilers' ..

That's accuracy, who can deny..

Oz

Carefully, til' Bub, Fox et al sees this, Mr. Tibbs!

I think we'll go safely unnoticed down here in the shed at the bottom of the garden ;)

Mr Tibbs

The scrim of noise disappeared when I slipped the preamp tray back into the case - all that`s left is music - between the lower overall noise floor and the effect of the tracos on the phono cards through the 1086`s, sounds really pop, they just emerge from a very black background, transients are produced with lots more authority/realism. Bass is taught and drum tones are remarkably clear. Lots of air up top. This sounds gooooood, particularly considering the ps/tpr/traco/case/hardware total cost was about 150 pounds.

Gotta get 2 more for my naxo....

Very good :)

I found myself nodding my head as you explained the difference to the music - It's just as you say.

Gotta get 2 more for my naxo....

The exact same effect should happen in the naxo. It almost makes me want to try going active with my Ergo III's...

Mr Tibbs

Hello Mr. Tibbs,

I was wondering what mods you have done to your NAC102 other than the Traco DC-DC things and taking out the 27kohm resistor at each 24V feed.

Is everything else standard?

My NAC102 has no phono stage. I would therefore need 6 1086's. I was wondering if it would be possible to have a picture of where the 24v supplies feed in close up.

I was wondering if feeding the Traco's with more than 24v would change the sound?
Say 30V or 36V?

Also if the 30v Traco output voltage was dropped to 27-28V through the 1086's would this improve the sound also? talk of using higher voltages through Naims pre-amps...

I was wondering what mods you have done to your NAC102 other than the Traco DC-DC things and taking out the 27kohm resistor at each 24V feed.

John, the beauty of a 102 is that it (IMO) needs only power supply mod's to really start to sing. There is one circuit mod I have done, that involves putting a RC filter on the power feed to each of the four 330k/330k input bias resistors, but forget about that for now. It's is little tricky if you're new to this kind of thing.

My NAC102 has no phono stage. I would therefore need 6 1086's. I was wondering if it would be possible to have a picture of where the 24v supplies feed in close up.

Look back to the photo's I've posted up and you should see where the 1086 output wires meet the main PCB. Compare that photo to your 102, and you should see the missing 27R's on my 102. After taking out these resistors, you should solder in a pin at the circuit end of each stage - this will make it easy to connect up your 1086 output wires when the main PCB is back in place.

I was wondering if feeding the Traco's with more than 24v would change the sound?

No, they are designed to deliver the same performance over the entire range of input voltage.

Also if the 30v Traco output voltage was dropped to 27-28V through the 1086's would this improve the sound also? talk of using higher voltages through Naims pre-amps...

I would stick to 24V for now. If you get the Traco's/1086's working as advised, you won't be too concerned about other mod's for a while :)

Make sure you get the Traco's/1086's up and running on the bench with some dummy loads to check all is well before fitting to the 102. Good luck!

Mr Tibbs

Mr Tibbs,

Do you have much voltage drop by your RC filtering? With a coil and few caps.

Oz

Do you have much voltage drop by your RC filtering? With a coil and few caps.

Less than 0.5V give or take. Not a lot anyway - the inductor has very low DCR, that's what is cool about them.

Mr Tibbs

Please tell me more about that specific inductor so I can ask for it, please!

Oz

Please tell me more about that specific inductor so I can ask for it, please!

I used a 470uH power inductor, rated at 0.3A. I had a couple in my parts box. Something less like say 100uH with the same rating would do fine. I will (when I get time) bring home a 'scope and play around with some alternative LC values to get the best result. With 1086 reg's, the filters do not appear to be too critical.

Mr Tibbs

Paging Jo Sharp and billinjapan

How are you getting on with the Traco's?

Hope things are going well, but do please say if there are any doubts.

Mr Tibbs

waiting for 2 x 100uH inductors to arrive so I can add the Pi filter. Doesn't seem fair to make a public assessment until I am testing them in most favourable circumstances.

But encouraging results so far, with still a minor reservation on the mid-range.

Jo, don't concern yourself about making public any reservations you're having. The Traco's seem to be stirring up a bit of interest and I'd rather people were cautious until they prove to be 100% effective along with local SR's.

The filters may make all the difference. I'm thinking also that the Traco's may need to be kept physically away from the SR's, to prevent the possibility of them interfering with the SR's. If this presents a problem (or is too much hassle), then some simple copper shielding may be just as effective.

HTH

Mr Tibbs

No regrets at all on my on my part about this mod - I`d recommend it enthusiastically. The tracos provide a really clean window that allows the other mods that I`ve done (the tpr`ed power supplies, oscons/silmics removed SOAR circuit and new caps in the amps, silmics and wima caps in the preamp, oscons on the phono cards) to shine through. Wish I had done this before the other mods, in retrospect it would have made assessing them a lot easier. The presentation may be a bit softer/rounder than if I`d replaced stock parts w/stock parts, but it`s really beguiling. Resolution at low volume has increased appreciably, but the temptation to turn it up is very hard to resist.

On the downside, I find listening to the ipod or the crap DVD I`m using now fatiguing after a half hour or so, the added clarity really reveals the quality of the source components and software.

Am still wating for my CEC to come back from the shop - all the moving parts are being replaced, so it should sound like new. Have a couple of Bill Evans XRCDs under the tree to test it with...

The gear is a 42(.5), naxo 2X4 (both kindly done by N. McB years ago) 2 NAP 140s, 2 lawtronics power supplies w/ tprs and tracos, a Xerxes/DSU/XPS 3.5/Dynavector/OL Rega 250 w/incognito wire, a CEC TL2/Polyfusion 800 dac w/ Madrigal cable, and Harbeth Compact 7s. Interconnects are all homebrew Canare mike cables, power cords Cardas homebrew, speaker cable is NACA 5. NACA5 kind of dark sounding, would like to replace it. Suggestions?

The hiclone I was using before building the new PSs is going to replace the DSU on the Xerxes when I buy or build a new regulator board, and the diode bridges in the 140s will be replaced w/Schottkies when I get FWB boards from Les. Will also traco the NAXO at some point in the near future.

As things stand, music sounds very natural and lifelike. Acoustic jazz and female vocals are just enthralling. That said, if anyone can perhaps recommend a way to improve things further, (given my limited technical expertise) I`m all ears.

On the downside, I find listening to the ipod or the crap DVD I`m using now fatiguing after a half hour or so, the added clarity really reveals the quality of the source components and software.

Excellent - your 42.5 preamp is obviously handling the signal much more precisely. Garbage In, Garbage Out. ;)

As things stand, music sounds very natural and lifelike. Acoustic jazz and female vocals are just enthralling.

I've recently gone through a stack of music I haven't listened to in a while. I came across a few CD's I'd bought and never really got into - several by Taj Mahal and Eric Bibb that left me feeling a bit underwhelmed, for example. Now, having played them over, I've been really enjoying these albums. There is a new found 'emotional charge' to the music that just never made it to the speakers before. It would seem that in music where there is a lot of subtlety in the performance, small losses of information can have a fairly drastic effect on level of enjoyment - for my ears anyway.

The slightly less subtle sounds of Joe Satriani's chops and licks sound better than ever, into the bargain :)

That said, if anyone can perhaps recommend a way to improve things further,

I hope the Traco's in the naxo will do just that!

Mr Tibbs

Another update:

When I put the two newly built PCB-mounted Traco/1086's into the 102, I made a small compromise on the 0V link from each PCB to the preamp star point. The link wire from one board had to be approx 40mm long, due to the orientation of the board. This being the case, I made the other link wire identical in length (even though it didn't have to be that long) so as not to have the two boards performing differently.

I figured that 40mm of wire would make little or no difference to the final result, so didn't fuss about it at the time. It nagged at me though (it's a DIY thing ;) ) so I got a spare hour today and sorted the thing out. Basically, one of the boards had to be rotated through 180 degrees, so that the 0V track of each board was right up beside the preamp 0V point. The 0V link of each board is now only 5mm long.

The verdict? - right from cold there seems to be something extra going on :) I'll leave it at that until I've had a proper listen.

Before;
http://www.btinternet.com/~david.stewart37/102pics/Traco2.jpg

After;
http://www.btinternet.com/~david.stewart37/102pics/Tracorelocation.jpg

Mr Tibbs

Mr Tibbs,
have you had a chance yet to put a scope on the output of the converters to see how they look.

have you had a chance yet to put a scope on the output of the converters to see how they look.

Nope, not yet. TBH (for this application) the need to measure seems pretty academic. With or without the LC filter, I can barely hear any difference. This may not be the case with say SR's after the Traco's.

What I think I'll do, (sometime in the new year) is get hold of another Traco and bring home a 'scope for some proper bench testing. The idea here, is that if the converters can be quietened enough to happily power digital circuits, the path is then open to build a small outboard CD player supply. It would be interesting to have something compact that could compete on equal terms with say a XPS. Anything less would be a non-starter as I already have a CDPS (a very good PS, BTW). Something small would be good, as it could sit right behind the CD player, giving some of the benefit I'm hearing on the preamp. Might all come to nothing though, we'll see :) Anyway, some daring individual may take up the challenge and do all the hard work for me - I know just the man, but for now he must remain anonymous...


OK then, the latest tweak has had some serious listening - the result is subtle, but a step forward without a doubt. Just a dash more of everything the Traco's managed in the first place, so well worth the effort. The rule is simple - the 0V output pin of the converters needs to be as close as possible to the preamp 0V point, if maximum performance is to be realised. I suppose I could usefully redesign my little PCB's to achieve even better performance, but it's not bad now...

Mr Tibbs

Unfortunately I have reached what seems to be a dead end with the Tracos in my 102.

First version was feeding the 6xSRs directly. There was a small but noticeable improvement in some mid to high range clarity - diction of words etc...and a slightly cleaner bass. But problem with noise from both the volume and balance remote control circuits.

Version 2 introduced the cap-inductor-cap Pi filter on the Traco outputs. Bass was improved further but the noise problem remained.

Version 3 was to remove the SRs and replace with LT1086 regs (what an effort!!!) but this did not sort the problems....noise from the control circuits remained and there was an increase in the background hiss from the pre.

Over the next few days I will return the 102 to its usual 6x SRs and try the Tracos in my old 62 for comparison.

I haven't given up yet as there were certainly promising glimpses of good results from the Tracos if only I can suss the noise issue...and I don't have access to a suitable O'scope for diagnostics.

Jo, you got any pics of your 6x SR setup? I use 4x SRs in my pre and would be interested in your implementation.

Cheers,
Carl

carl,

I'll take a few shots when I get the SRs back into the 102...early next week probably.

jo

Version 3 was to remove the SRs and replace with LT1086 regs (what an effort!!!) but this did not sort the problems....noise from the control circuits remained and there was an increase in the background hiss from the pre.

Damn and blast - that's a real shame. Sorry they didn't deliver for you, Jo.

However, I feel something is definitely amiss because the Traco's/1086 reg's should have blown you away - certainly a hell of a lot more than the small improvement you mentioned :confused: - I'm hearing stuff now that my 102 (in any previous power supply configuration) never even hinted at before.

I haven't given up yet as there were certainly promising glimpses of good results from the Tracos if only I can suss the noise issue...and I don't have access to a suitable O'scope for diagnostics.

I salute your doggedness. When you get around to playing with them in your 62, do post up some photo's if you can, as I feel I could help you better if I could see what's going on. Hopefully it will be plain sailing and you really will get to hear some of the magic of an isolated 0V system.

Mr Tibbs

Jo - you're welcome to borrow my scope if it would help.

Mr T,

I'll email a few pics of the version 2 to you tomorrow...and we can chat in private by email perhaps to further compare notes.

Martin,

a very kind offer....are you within (reasonable) driving distance of Salisbury?


Jo

Straight up the A36 in central Bath

Please consider posting parts of your email dialogue here - I'm learning a lot from this dialogue :-)

I'll email a few pics of the version 2 to you tomorrow...and we can chat in private by email perhaps to further compare notes.

Good idea.

Mr Tibbs

Jo has been in contact and (hopefully) we've identified the main problem of strange noises when using the remote volume and balance controls. It's a small mistake anyone could make, so I'm sure he wont mind if I pass this info on.

This is really a NAC102 specific problem, which stems from the fact that the 102 needs some form of external power supply to drive the control circuits. Jo had used the output of one of the converters to power the control stuff, the problem here being that as soon as he operated the remote volume control, the (substantial) extra current demand of the motor was probably enough to overload the converter, making it object accordingly!

That aside, the control circuits are continually noisy and this would no doubt be pulling down the performance of the converter driving them, affecting the local reg's and therefore the signal circuits being fed by the same converter.

There are at least two options to get round this problem. The easiest is probably to build a small separate conventional NAPSC type supply and use it to power the control circuits in the usual manner. What I did was to use half of my split (electrically separate) 0V Hicap to power the Traco's, and the other half to power the control stuff. There is another possible option, but it involves the use of a third DC converter in the preamp, and I don't want to go into detail about it until I've proved it works properly.

Using a separate (NAPSC or half of a split 0V hicap) supply for the control circuits means that the external 0V of the separate supply will be common to the preamp 0V point, but this will have no impact on what the converters are trying to achieve in isolating the main power supply from the preamp signal circuits. The converters are still able to make the preamp perform as if it has no external cable link to an outboard supply. Remember that simply connecting up some sources (CD, Tape, VCR etc) means that the ground of these sources is tied to the preamp 0V point, but they shouldn't interfere with the function of the signal circuits - whether fed by a conventional outboard supply or internal DC converters.

HTH

Mr Tibbs

Thanks Mr Tibbs

... This might be:

http://www.btinternet.com/~david.stewart37/Drawings/MultiTraco.JPG

The use of multiple DC converters opens up another possibility - virtually the complete elimination of shared signal and power in the preamp 0V system. With one converter per stage, and the 0V point of the converter close-coupled to the stage itself, the preamp star 0V system is no longer carrying power - it simply becomes a voltage reference system for all of the signals.

552 anyone?

I'm tempted to give this a go, but need to think it through a bit more and I would only try it after doing some work on the bench with a 'scope, to see what the optimum CLC filtering is etc etc.

Mr Tibbs

That definitely looks worth trying.. it's basically four-wire sensing of the signal, because you've got two completely separate loops. Just like using a separate PSU for a CD player clock is a good idea - there's no intermod of signal and power in the ground connection.

Looking forward to more of your investigations...

Suggestion:

Another way of seperating signal return from PSU 0V is to use some variant of "balanced" design or operation; I know various US designs do this - Mark Levinson for example. In fact to get the benefits you don't need to have full anti-symmetry - judicious (sp?) use of differential operation allows you to get most of the benefits without making things too complex. For example, making the pre-amp line inputs differential, so they measure voltage between the pins of the line sockets, without imposing a hard connection between signal low and pre-amp earth.

I have just re-read the last sentence, and fear it is completely unintelligible - I know what I mean!

I have used techniques like this in instrumentation electronics - it worked very well in that context.

I have no idea how (or if) this could be done as a mod, or if it means starting with a blank sheet.

I have just re-read the last sentence, and fear it is completely unintelligible - I know what I mean!

I know what you mean! I agree 100% with what you're saying, but unfortunately (I think) you are right again when you say it would need a blank sheet.

That aside, my main interest in modifying kit (specifically Naim preamps) is centred around seeing how much extra performance can be gained, without actually changing the make-up of the individual circuits. It turns out an awful lot can be achieved just by playing with both ends of the power supply.

I suppose I'm looking for ideas that are big on performance but are (relatively) easy to implement and (most importantly) have no negative impact on the aspects of sound quality that drew me to Naim kit in the first place.

Looking forward to more of your investigations...

LOL... I need some sponsorship. I must try a begging e-mail to Traco... :)

Mr Tibbs

Overnight I have had another insight, which just might be relevant.

The aim of a regulator circuit is to produce a constant output voltage, in the face of varying input (rejection ratio), varying load (output impedance) and hoping to avoid internally generated noise.

I would like to add a fourth criterion - high input impedance; the current drawn from the upstream supply should not vary as that voltage varies. Optimising this input impedance is not normally a criterion in PSU design, but minimises noise injection into the earth terminal.

I have a first cut of a discrete design (as a spice network) which is designed with this in mind; it simulates nicely, but has not been built, so a large pinch of salt is needed. I get about 100db rejection ratio (flat to ~50kHz), low output impedance (<< 1mOhm, flat to 50kHz) in the simulations. A pen and paper estimate suggests about 20uV rms of broadband noise; my version of spice doesn't understand zener noise so I couldn't simulate. Most importantly, the input impedance should be high - many kOhms, shunted by relatively small junction capacitances.

I can send the spice netlist to anybody who can make use of it - ask via a PM. A conventional schematic will take a bit longer - I have to learn how to drive my new schematic capture software (gschem from the Geda project), and time is scarce during the working week.

It uses 4 small signal bipolars (BC547/BC557) + 1 medium power bipolar (BD139/BD140) + 2 JFETS in current sources; major defects are relatively high dropout voltage and lack of shortcircuit or thermal overload protection. Simple current limiting adds another transistor, and costs a tiny might of rejection ration at high frequencies.

Purely on 22UF 35v tants for the LT1086's, farnell has cheap ones (multicomp) and expensive ones (avx) - does it matter?

thanks,

Jon

Jon, I'm sure the cheaper tant's will be fine around the 1086. It would matter more if you were changing out tant's in the signal path. I usually go for Kemet tant's and they are not cheap either.

Mr Tibbs

I'm baffled - I had a couple of cheap DC/DC converters made by Ericsson and used these to make a 24-0-24v supply for my pre-amp. It sounded a little rough without regulation so I moved some SRs into the pre-amp to regulate the positive side. Much better and very nice sound, but I was frustrated that I was underpowering the SRs.
I came across some Traco convertors in Farnells bargain bin and spent a few hours swapping things round to get 30-0-30v into the SRs.
Result - nasty treble. I put it down as a burning in thing, so left it all yesterday and last night so settle. Today it's still sounds rough - the detail is there but it's lost that nice analogue sound it had with the Ericssons.
Any ideas before I put it all back? So disappointed :-(

I came across some Traco convertors in Farnells bargain bin and spent a few hours swapping things round to get 30-0-30v into the SRs.

I'd need lots more info - why the need for 30-0-30V? (seems excessive) Is your preamp split-rail modified? If so, DC converters may not offer any advantage - this is new territory for them. Also, what model of Traco's did you get hold of? Some of them have no regulation and no case shielding, so best avoided for audio use.

More details please!

Mr Tibbs

Whats the rest of your system Chris ?

I ask because I have a 102 that I wil make a PSU for and have been watching this whole Traco thing with interest but as there are differing opinions "I just don't what to do with myself" ...:confused:

Hence asking about your system, I hope that something isn't as good as it might be and that the pre amp is being amazingly revealing - which would be a good answer. For example, bitstream based CD Player that hasn't been refined (bodged) would be a good explanation.

Could I use one of these for my PSU ?

http://cgi.ebay.co.uk/Toroidal-Transformer-2-x-25V-O-P-60VA_W0QQitemZ7587635700QQcategoryZ71391QQrdZ1QQcm dZViewItem

I'd need lots more info - why the need for 30-0-30V? (seems excessive) Is your preamp split-rail modified? If so, DC converters may not offer any advantage - this is new territory for them. Also, what model of Traco's did you get hold of? Some of them have no regulation and no case shielding, so best avoided for audio use.
Mr Tibbs
Sorry for the confusion, they are 2 Traco converters of the 3 series (TEN 3-1223) - 9 to 18v in to get +/- 15v out. So I have 30v per rail.
The Traco site gives:
Line regulation: ±0.5% max.
Load regulation: - Single output models: ±0.5% max.
- Dual output models: ±1.0% max.
Ripple & noise: <50 mVpk-pk (20 MHz BW)
Conducted EMI: EN 55022, class A and FCC, level A (internal filter)

By split rail modified, do you mean the recent mod suggested by Andy Weekes? - if so, no; its an Avondale modded NAP42.5 with Linnik's recent "xmas" mod. The cd player is an Avondale AA5 and the power amp an Avondale A260z.

they are 2 Traco converters of the 3 series (TEN 3-1223) - 9 to 18v in to get +/- 15v out. So I have 30v per rail.

OK that's more clear, thanks. Had a quick check on the Traco site. They are regulated (good), they are plastic cased (not so good). You need to make sure they are operating within their current limit (100mA max for this model) - you should be OK if not powering phono modules, but check anyway.

Check to see if you've got true isolation on the 0V rail (how-to explained earlier in this thread) and check your SR's have enough headroom (6V is good). Re-check all connections (we all make mistakes).

Today it's still sounds rough - the detail is there but it's lost that nice analogue sound it had with the Ericssons.

Hmm... 'rough' means something is very wrong. The sound I'm getting is very clean and clear, and that is not always an advantage. On well balanced recordings there is no problem, but if the recordings are on the 'bright' side (which is not uncommon, and engineered that way due to the fact it makes the music sound more 'impressive' on a typical low-res system), then the result may be too bright for some ears - but, I've never heard anything sound remotely 'rough' since the Traco's were fitted.

Did you try LT1086's as local reg's?

Mr Tibbs

Im not powering any phono boards and hoped that the +/- 100ma rating gave some headroom. The 0v is isolated from the incoming supply, but I will double check.
Maybe its the brightness, I'm very sensitive to it and cant listen to a setup with too much treble (for my ears). The rest of it sounds great, but I'm easily distracted by the upper registers. I might try a bit of attenuation in the tweeters before making any further conclusions - I'm sure this is the right way to go, it just needs a bit of fitting into my system.
Thanks Mr Tibbs.
edit: no I didnt try local regs - the supply is 2 x 12v transformer - 2 Kendiel 15000 cap - TPRs @ 15v (down from 18.5v) - into the pre-amp to 2 x Tracos - +ve sides regulated by SRs.

Im not powering any phono boards and hoped that the +/- 100ma rating gave some headroom

Just so you know (probably you do) the quoted 100mA per rail works out at 3W of output power from the converter (100mA x 30V = 3W) hence this model is called the Ten-3. - Not a lot of power in other words!

Maybe its the brightness, I'm very sensitive to it and cant listen to a setup with too much treble (for my ears). The rest of it sounds great, but I'm easily distracted by the upper registers.

If they're doing their thing, the bass and midrange should be very noticeably (unmistakably) better than without them. The treble is where things start to get tricky - so much depends on everything else in the chain (a bright tweeter, for instance) and personal preference plays a big part too.

Another thing - SR's as local reg's are very good at improving the treble response of a preamp and you may find that something less good in this area (like the 1086's) may prove a better match with the DC converters, to give a more 'balanced' overall result. Just an idea.

I'll be very interested to see how you get on with them (good or bad!)

Mr Tibbs

Chris, something else - assuming you've removed the 27R of the input RC filter to each stage, you might find that some resistance here could go a long way to taming the treble. A few ohms could make all the difference (you'll need to have the 47u cap in place).

Other stuff:

Today I've had some time to try out a little bit of inductance between the 1086's and the stages. Just some turns of wire on a screwdriver, with sellotape to hold the coils together;

http://www.btinternet.com/~david.stewart37/102pics/inductors1.jpg

http://www.btinternet.com/~david.stewart37/102pics/inductorsin102.jpg

Early days, but already they are making their presence felt. A touch less fiery at the top end, with seemingly even more detail being resolved.

Mr Tibbs

I am actually living thru that Tibbsie. But without Tracos.

Remember I have those dedicated 0V leads and divided power rails in both gain and TA buffer stgs. And also the resisting inductors before stgs. 6xLT1086 secregs in the 62. No RIAA.

Maximum detail, veerry musical. But a bit, just a bit overriding top end. And a hint shy bass. Very nice with my 70's tuner which somewhat gives more low end and arrests a little the top end.

I have been thinkin it is my new type tweeters in Keilidhs which I have never compensated by -0,5 - 1 db tailoring in the aktiv x-over as I think is recommended. Now when I have got the amps re-capped and giving the top end thru again, this may be the way for me.

Oz

Chris,

If your bad sound is a leading edge thing rather than balance and you havn't got the 5.6pF mica caps between base and collector of gain stage Q5, these might help. Actually C0G ceramic and values up to 47pF will do. I'm using 10pF and LesW recommended the 47pF or was it 27pF.

David

The 47pf was on the base/collector of the ztx214 on the buffers, 5.6pf on the b/c of the first transistor on the gain board.

Why not try these coils with a 1R up the middle (LCR)........on the input to a reg and at the circuit.

http://www.geocities.com/macsurplus2003/DSCN3208.JPG

http://www.geocities.com/macsurplus2003/DSCN3207.JPG


Graham

My top end thrill could also be that I am still missing that mica cap from the transistors. I will soon have suitable caps from Australia, so it will be done then.

Oz

Graham,

Are you having the green (0V) lead into the same post than the inductor (+V) ???

Oz

5.6pf on the b/c of the first transistor on the gain board.

Carl,

No doubt the buffers benefit too. A typo? The transistor involved in each case is the one driving the output, whose collector is directly connected to the +ve supply. www.acoustica.org.uk has a diagram under Naim preamp mods bible section. You actually have to click on fig5 as the thumbnail doesn't show it.

David

Graham,

Are you having the green (0V) lead into the same post than the inductor (+V) ???

Oz

No Oz, just a funny angle of the photo. all 0v's (on each reg) go back to the centre tap of the transformer.

Graham

Graham,

Thanks. Good to see your photos. It gives more courage to go into CDP!

What happened in the sound when you put those s-regs into it?

Oz

Carl,

No doubt the buffers benefit too. A typo? The transistor involved in each case is the one driving the output, whose collector is directly connected to the +ve supply. www.acoustica.org.uk has a diagram under Naim preamp mods bible section. You actually have to click on fig5 as the thumbnail doesn't show it.

David

Exactly what I meant to say. On the buffer stages, the transistor you need to connect the 47pf cap to is the PNP ZTX214 (Q2 on fig7). On the gain stages, it is the ZTX384 (TR5 on fig5). One thing to note is that the pins are different on the 214/384 trannies because they're PNP/NPN. Always connect the cap across base/collector.

Hope the clears up the confusion!

Graham,

What happened in the sound when you put those s-regs into it?

Oz

Ye Ha............yes baby yes baby yes............

Try some Jensen 4 poles caps in any PSU .........ooooooh yes baby.

Graham

Okay, I found the Jensen cap site.

Hmm. Have you tried Jensen cap in NAC feedback?? Comes into my mind..
How big Jensens have you used in PSUs?

Is that CDP a CD3 or 3.5 ??

Oz

The Jensen cap distributor for U.K. offers the ALPS Blue motorized pot for quite cheaply: http://www.worldaudiodesign.com/catalog/product_info.php?products_id=136

Oz

That's the 50k version... don't our 62s need the 20k version? I'd *love* to add remote control to my 62!

Personally I don't as it's only few steps. After all, the remote is always few steps away from me when I need it. It will never be as precise as the BIG knob of old chrome bumper 62 volume knob. Unbeatable. But I have to change the FB resistors to lower the gain. Then even better.

Oz

http://www.in-your-mind.com/NAC-6regged.jpg

Oh, it's not because I need remote control... I just like the bodge factor of adding one ;)

Haha! I got it, Carl!

Yeah, it would be a "nice" challenge to implement the huge pot into the really full 62. At least if you have faith into the Evox caps..

Oz

Just so you know (probably you do) the quoted 100mA per rail works out at 3W of output power from the converter (100mA x 30V = 3W) hence this model is called the Ten-3. - Not a lot of power in other words!

If they're doing their thing, the bass and midrange should be very noticeably (unmistakably) better than without them. The treble is where things start to get tricky - so much depends on everything else in the chain (a bright tweeter, for instance) and personal preference plays a big part too.

Another thing - SR's as local reg's are very good at improving the treble response of a preamp and you may find that something less good in this area (like the 1086's) may prove a better match with the DC converters, to give a more 'balanced' overall result. Just an idea.
Mr Tibbs
As I got a pack of 10 of these from Farnell's bargain bin, I planned to use extra converters for different circuits if needed.
I did a bit of tweeter tweaking last night. They are Focal inverted domes and responded well to a bit of extra resistance in the path. It was only after experimenting with resistor values that I realised just how bright they were - an extra 15ohm in series to get it back to normal. Much more listenable although I didnt have much listening time, I'll see tonight how it goes.
I'll try the inductors, I have some around I could use. Is the idea wit these to cut out high frequency noise? Also why does local regulation have more impact than non-local on the treble?

Okay, I found the Jensen cap site.

Hmm. Have you tried Jensen cap in NAC feedback?? Comes into my mind..
How big Jensens have you used in PSUs?

Is that CDP a CD3 or 3.5 ??

Oz

Its a CD3....and the caps are 10000uf 63v jobbies but I use them in my pre as well.........very nice.

Graham

As I got a pack of 10 of these from Farnell's bargain bin, I planned to use extra converters for different circuits if needed

Lucky! I paid top dollar for my measly two. (best £50 I've spent though ;) )

I'll try the inductors, I have some around I could use. Is the idea wit these to cut out high frequency noise? Also why does local regulation have more impact than non-local on the treble?

Look back in the thread and you'll see info about making up a CLC filter for the output of the converters (goes between the converters and any local regulation). After the local regulation (whatever type you use), a low value RC filter might help (a couple of ohms R/47u). Or simply some turns of wire (as above), forming an LC filer with the existing 47u cap. Or, a combination of all three, making up a RLC filter.

DC converters work at about 300kHz and are pretty noisy (like all SMPS) and it's normal practice to filter their outputs. That said, I first tried the Traco's in my pre with no filtering, just LT1086 local reg's, and had no problems.

WRT local reg's impacting the treble - I probably didn't make myself too clear. What I mean is that Traco's (like SR's) are very good at cleaning up the treble end, and if you use SR's as local regulation along with the Traco's, you may end up with a treble that is too open (depending on tweeter, personal pref etc). LT1086's are not as open at the top end as SR's, so may be a better match for use with Traco's, giving a treble that is detailed but not too bright. Hope that makes some sense.

Mr Tibbs

Graham,

Please tell more about the differences against Kendeils (as you had them, didn't you?!) and... How much you paid for the Jensens?

Oz

Graham,

Please tell more about the differences against Kendeils (as you had them, didn't you?!) and... How much you paid for the Jensens?

Oz

I've tried every type of cap Oz, in every location, in every colour, in every bit of kit I have..................but these 4 pole jobbies are very, very, very good indeed (compaired to anything else I've used)

Everything is tangable, almost real....!!!!!! or having a sence of realisum. All seems to be 'together' within the mix. (Music) This is scary stuff.........Oz

4 caps (10000uf 63v) cost 850DKK or about 22.00 UKP each and thats having to pay their TAX at 25% but includes postage. So not so bad.

Their so good, the cost is almost irrelevent.

2 day delivery....go for it Oz you know it makes sence............

Graham

Did they deliver directly even they have a d-butor in U.K. ??

Oz

Did they deliver directly even they have a d-butor in U.K. ??

Oz

Direct Oz

pls see email

Hello Graham,

My direct tel.no. is: +45 43 27 16 70. Normally I'm in the office from 8.30 - 17.00 Danish time (1 hour ahead of U.K. time). If I'm not in, someone else can help you.

Please call me.

Best regards
Hans J. Jensen

I had no problems dealing direct............World Audio (Jensen UK distributor) did'nt answer my enquirys.............so I went direct........Hans is a very nice man and speaks very good English. All he needs is your credit card details and what you want and it turns up two days later. It did for me anyway.

BTW. I am also trying the BHC T-Power 4 pole caps (£25.00 each) this week so you may wish to wait for the head to head Jensen vs BHC.......but then again I think both manufaturers products are going to be very good and there will be nothing in it. The Jensen is the better value for money unit though.

http://www.geocities.com/macsurplus2003/DSCN3212.JPG

Installed (not yet completed) in the CD3 psu

Graham

Wondering if they fit to a NAP by 140 style...

Can you please give me the measurements?
Burn-in time??

Cheers,

Oz

and thats having to pay their TAX at 25% but includes postage. So not so bad.



If you buy anything from the UK and are outside the EU they have to take the VAT off the price of the item. They are ripping you off otherwise. Most companies do it for international orders, but the ones who don't are just making some gravy they do not deserve

Wondering if they fit to a NAP by 140 style...

Can you please give me the measurements?
Burn-in time??

Cheers,

Oz

35mm dia by 50mm long.......but they have 4 connecting poles Oz so you would have to rejig (drill additional holes) for them to fit.

Burn in time, about a week seems to do it.............

Graham

Thanks Graham,

No, I have 110's but I have wired them for 4 caps as 140. No board.

Agisthos, you're right but we are in EU with Graham. Okay, I can buy with my company VAT reg number and have it tax free to me. But then my own tax man may later insist me to pay the tax here.. Jensen is in Denmark.

Oz

Last night, the sound with the Tracos was a completely different story. One change I made was to substitute a new 260z amplifier for testing. (If you read this Les, I sorted the bias, now I've managed to use a meter properly - doh!).
The original 260z wasnt built by me and uses holco resistors everywhere and other expensive part substitutions. The new one blows it away, even though it's only powered by an older NAP160 transformer. There's a lot to be said to sticking to Les's specs, it sounds much better balanced and had me smiling for hours.
Maybe the Tracos had settled in, maybe they where revealing the non-spec attributes of the power amp, but it sounds pretty damn good now. Very analogue, very involving and one of the best sounds I've experienced.

The original 260z wasnt built by me and uses holco resistors everywhere and other expensive part substitutions. The new one blows it away, even though it's only powered by an older NAP160 transformer. There's a lot to be said to sticking to Les's specs, it sounds much better balanced and had me smiling for hours.

I'm using bog standard (built by Les) NCC200's and I can say for sure that they definitely need absolutely nothing done to 'enhance' their performance. Plug and play!

Maybe the Tracos had settled in, maybe they where revealing the non-spec attributes of the power amp, but it sounds pretty damn good now. Very analogue, very involving and one of the best sounds I've experienced.

Very pleased to see that. A couple of day's burn in will get them sounding a tad smoother yet. I would urge you to add the little home-brew inductors - the sound is definitely better (not just different) with them in place.

Mr Tibbs

Added some inductance at the board power inputs, seems to have done the trick. Could emf in the inductors slow the response of the circuit though?

Could emf in the inductors slow the response of the circuit though

The very small amount of inductance involved means that they really only affect the response of the circuit way beyond audio frequencies. We get the benefit of filtering off HF noise and so lessen the chance of the circuit 'ringing' which could have consequences down into the audio range.

Mr Tibbs

Just a few hours ago I installed a board similar to what the illustrious Mr.Tibbs installed in his 102. My pre is a 32, and it's a single board with two SMPS modules (Wall Industries, similar in spec/performance to a Traco), and 8 LM317ATs. The board size was 2.5 x 3.6 and fits snugly in the space between the tape buffer cards and input buffer cards (just behind where the balance pot would be). I also did the 0v mod that moves the star point to the preamp at the same time.

My listening has been only at low levels thus far, and only digital (squeezbox 3). Even in this short, somewhat compromised listening situation, I can hear why he was so enthusiastic. Instantly noticed more dynamic variation and expression, more air and life, and a sense of ease and flow across the entire spectrum. All of this at a level that won't wake the rest of the family. Even at the low volume I could hear and feel bass note thumps and rumbles. Very eager to get the volume up a little more and let things run in. More reviews as I get time to listen.

I also have a pic of the board just before installing into the pre, which I'll try to post somewhere and link in.

Mr Tibbs, a huge thanks for this wonderful idea/inspiration!

Mike

I've had more time to listen, and at louder volumes. Short version: this change has brought more musical improvement and expression to my system than anything I've done before. Alive, expressive, engaging, human. Sonically, there's gobs more of everything and it's in the context of music, not sound. Mr Tibbs used the phrase "master tape" I believe to describe the sound, and that is a good way to put it. Feels like very little is between you and the intent of the performers and the piece of music.

I previously built a 6 x LM317 external PSU with separate lines to each card, and later a 2 x ALWSR SNAPS, both of which were steps up. This change is in a completely different league. I don't know that it's the SMPS specifically. It could be moving the regulation to within inches of the boards, or relocating the 0v to inside the pre, or the sum of those and the SMPS board that makes such a dramatic change. (Could be I botched the two earlier projects but got this one right??!)

Whatever it is, just 12 hours in I have much more of a musical experience coming out of my system than before, and certainly more than I expected, even given Mr Tibbs' descriptions. Can't recommend it enough.

I could put together a parts list with part numbers/sources, a board layout, and photos of how I installed it if it's of interest to anyone. I also have 2 professionally made unused boards that I made for this project, if someone's really eager.

http://www.monigle.net/board1.jpg

M

Mike,

Stunningly tidy layout on those boards!

Richard

Mike, I'm very glad to see you're enjoying the results of your labour :-))

You have done a great job with that PCB (puts mine to shame). Have you any pic's of it installed in the pre-amp?

Mr Tibbs

Thanks, Mr Tibbs, the board was actually easy to do and your work helped.

I wanted to snap inside pix, but was so eager to get it done and plugged in that I forgot last night. I will open the case over the weekend to test temps and make sure it's snug, and snap a few fix. It was not an easy thing to wire up! (And the final result is not quite as tidy as the board itself.)

Meant to underscore your findings with vinyl, the change is even more pronounced, (ie more lifelike, fluid and engaging), and conveys the "moment in time captured forever" sense of some recordings far better than I ever expected. Hands down the most _musical_ improvement I've ever heard, bought or built.

M

And thanks Richard, also

When Mr. Tibbs originally posted this I invitied him to put together a page for acoustica (http://www.acoustica.org.uk) as a resource in case this drops off the end of the database eventually.

I think Mike's comments (and stunningly 'right' looking board) demonstrate it'd definitely worth preserving - would you like to have a go Mr Tibbs, or would anyone mind if I cobble together a first pass for review from material from this thread?

Sounds like a good idea. I'm happy to share my layouts, suggestions and solution for wiring and placing my board design inside a 32/shoebox case. A challenge, but can be done. I can't imagine it would be any *more* difficult inside a 42/62. Anything larger (like Tibbs') would be a cakewalk in comparison.

And although I appreciate the comments on the board, it lacks any way to formally anchor it to the chassis or main board. If I were to approach any revisions, that's where I'd start. Mine has big dbl-sided foam blocks underneath the SMPS modules, and smaller strips at the opposite corners to hold it in place. Seems sturdy enough for now, and is right for the 32 implementation. The inductor I used is also larger than I spec'd, so I'd add some spacing there.

Feel free to contact me Martin for review/additional comments, pix, layouts, etc.

I wanted to snap inside pix, but was so eager to get it done and plugged in that I forgot last night. I will open the case over the weekend to test temps and make sure it's snug, and snap a few fix.

Thanks, Mike -- Looking forward to seeing the big picture.

Meant to underscore your findings with vinyl, the change is even more pronounced

Yes, the phono boards especially really seem to come to life with this PS arrangement. Give things another day or two to settle in and you should be on cloud nine. Thanks very much for your positive reviews!

...or would anyone mind if I cobble together a first pass for review from material from this thread?

Martin, please do - I'm quite sure you'd make a better job of it than me!

Mr Tibbs

Mike - thanks for re-opening the thread - it was just the incentive I needed to Traco my naxo, too. Parts are on the way. Beautiful boards, btw & glad you like the new sound. Hard to imagine otherwise...

Mr Tibbs - is the CLC filter between the converters and the 1086s a step forward sonically as well, or there for safety's sake?

Mr Tibbs - is the CLC filter between the converters and the 1086s a step forward sonically as well, or there for safety's sake?

Way back when I was just playing around with the Traco's in the 102, I added the CLC and really didn't hear much difference. I included them in the finished boards because they weren't doing any harm (to the sound) and were probably doing some good by reducing HF hash. It's easy to bypass them (just put a short across the inductors) and have a listen to the result - which I will (sometime) try with my own, now that I'm well used to how the pre sounds with them in.

Interestingly, the little home-made inductors that I later added on the output of the 1086 reg's, do seem to have some effect on the sound. The top-end is a little less 'fierce' with them in place. Feel free to experiment though - it would be good to hear of any tweaks that take the performance a notch higher.

Mr Tibbs

Before I installed my board, I put it on a 'scope to look for noise at the 317 output, as well as throghout the circuit. The CLC does reduce noise. The 317 stage (and the caps within it) does most of the work removing the noise. My SMPS (not a Traco) puts out quite a bit of upper freq noise, and the CLC filters some of it, which probably makes it easier for the 317 section. Not sure if the 317 stage out would be different without the CLC. Overall noise floor is better than a stock SNAPS, at least in my implementation with LM317ATs. I am likely going to build half of another board to use for testing, as I can't get inside the 32 easily to do any mods now the board is in place. But I'm curious to know what might improve things.

Also, I didn't put inductors on each stage of the preamp, I just replaced the 27r on each card with a 2r and left OSCONS as the filter cap on each card. I have no issues with high freq nasties or edge thus far. It sounds as smooth as before, perhaps even more so on good sources.

I am likely going to build half of another board to use for testing, as I can't get inside the 32 easily to do any mods now the board is in place. But I'm curious to know what might improve things.

Good man - that's exactly the sort of thing I hope will happen (that people will take the basic idea and improve it). Once in a blue moon I get an idea that might be worth trying but when I get the spare time to try it I usually crash in front of the stereo instead ;-)

Also, I didn't put inductors on each stage of the preamp, I just replaced the 27r on each card with a 2r and left OSCONS as the filter cap on each card. I have no issues with high freq nasties or edge thus far. It sounds as smooth as before, perhaps even more so on good sources.

The small r / OSCON filter is pretty safe bet I reckon. Your description of the sound would suggest you've got the balance just right.

The rationale behind the use of DC converters/local IC reg's was all about trying to get a one-hit complete fix that is actually NOT particularly tweaky in nature, and doesn't need anything special as a primary supply (no huge toroids or multiple transformers). A kind of fit-and-forget solution to the main problems associated with trying to maximise performance from Naim preamps, as far as power supply goes. That said, I guess there will always be a better way to build a mousetrap!

Mr Tibbs

Well it's equally an elegant and effective approach, at least from where I sit. I think its success might be due to the fact that it's approaching both sides of the power supply problem from a single point, and/or a single solution, and providing both with an equal level of noise/performance. Perhaps anything that impacts one side of the PS equation affects the other side equally (or nearly equally), which might retain a sense of balance in how the resulting music is relayed. Just my speculation. (I guess that is sort of how a split supply works, isn't it.)

One problem has appeared: heat. The 32 case is very warm to the touch. I don't think it's affecting performance of the music, but I will research more over the weekend.

One other comment about the mod as I continue to listen to a range of sources: the pre is now revealing and almost ruthless with regard to the _sonic_ aspects of different sources, but it seems to unlock music from all of them. Low bit-rate MP3s, Internet Radio, and live recordings all immediately reveal tonality problems and noise, more so than previously, but the music in each seems to comes through, better than before in most cases.

M

Sounds like a job really well done, Mike, your comment: the pre is now revealing and almost ruthless with regard to the _sonic_ aspects of different sources, but it seems to unlock music from all of them. struck home with me - it's exactly what I prize in mods I consider to have gone 'right'.

2R + Oscon (i presume 47R) looks like a really good mix, starting to roll-off about the point that the three-pin regs own noise starts to rise (-3dB at about 1.7Khz) and will kill a lot of noise feedthrough, giving up to 35db rejection of feedthrough (http://www.pinkfishmedia.net/forum/showthread.php?p=314263#post314263) at HF - limited only by the Oscon's ESR. NB you can go as low as 0.33R in series and still have critical damping of a 47uF oscon with the 317's effective output inductance, i.e no unwanted ringing. Drop below that and hardness appears in the midrange, followed by a lisping treble.

One problem has appeared: heat. The 32 case is very warm to the touch. I don't think it's affecting performance of the music, but I will research more over the weekend.

Mike, If I've read your earlier posts correctly, then apart from the converters, you've not had local reg's inside the 32 until now.

The reg's plus the converters could be creating about 60% more heat (in addition to that created by the amp components) in the preamp. You can easily work out the total amount of heat being generated, as almost all of the current going in is turned into heat. For instance, if the snaps is delivering say 300mA @ 24V, then approx 7W of heat is being created inside the 32, with the converters and reg's making up about 2.5W of that. Measure the current leaving your snaps and we'll get a better idea of what's going on (and see if it seems excessive).

Another thought - can you measure the case temp? (a cheap thermometer will do).

Mr Tibbs