the Deltec / DPA webpages

Deltec Precision Audio - later relaunched as DPA Ltd - was started by Adrian Walker and Robert Watts while both were studying at University of Cardiff. Following the apparent final demise of the company c. mid-1999 further information seems to evade Google, so here is a set of pages the internet so obviously needs.

Deltec equipment was always considered strikingly original in terms of conceptual and electronic design, execution and the resulting musical presentation. If Deltec gear can be said to have a 'house' sound it's one hallmarked by unusual clarity and neutrality; 'it is usually very transparent with exceptionally detailed treble and midrange, with bass majoring on speed and agility over weight and 'slam''1.

To all intents and purposes Deltec and DPA are the same thing, but technically the name change represents the two incarnations of this company. Deltec went bust on May 29th 1992, but was later re-born as DPA Ltd. If your item comes with glossy grey case work, has the serial number on the rear as opposed to the base, then you are looking at a Deltec product. Later products moved to a flat powder-coated facepate and matt grey cases; later still as DPA came black perspex faceplates with polished stainless-steel casework - for examples see the 1997 brochure.

To start with: an insight into some of what Deltec were trying to achieve: an Interview with Rob Watts, in Hifi World, June 1991: Page 1; Page 2


the list of products

Heres' a list of some of the various products developed by Deltec / DPA over the years. Many contemporary reviews and other information is available - just follow the links. Apologies for the poor quality of some scans; these are taken from seconhand photocopies. As ever, please contact Martin if you can help provide more information or corrections for the benefit of other visitors.

Preamplifiers

CTA 80

Deltec's first product, based on the Analog Device MA332 opamp. Adrian Walker recently commented:

"The first product that Deltec Precision Audio produced was the CTA 80 a pre-amplifier, CTA standing for Control Amplifier. It was housed in a steel grey metal box and looked very "different" for the time. In truth it was ugly, but sound great compared with anything on the market including, MF, Naim, Linn, etc.

It was based on a a high-spec operational amplifier the Analog Device MA332. The MA322 was both expensive and limiting and so we designed our own operational amplifier based on thick film technology using SMDs and was called the DH0A32, which was used to delelop both the pre & power DAP50 range.

The DHOA32 was and still is a very remarkable design and still holds many design records.

It took some time to develop the DPA50s range and so we filled the time gap and coffers by quickly designing the Solid Link range of cables."

 

DSP50S

Preamp with onboard MM/ MC phono stage and power supply

 

DPA50S

Substantial revision of the DSP50. Phono stage and power supplies moved into separate offboard cases, alleged to sound even better as a result too. Gains seprate left/right fine-gain controls to effect channel balance
Photos:Inside - overview; Photo detail of Deltec's DH-0A32 SMT discrete opamp
Reviews:
HiFi World, April 1991: Page 1; Page 2; Page 3;
The Audiophile, July 1991: Page 1; Page 2

 

DPA50S Phono stage

MM/ MC Phono stage. Reviewed in The Audiophile, July 1991 (above)

 

DPA200S

Half-width case, matches DPA200S power amp. Push-button source selection and balance control; manual volume control.

Reviews:
Hi Fi World, July 1993: Page 1; Page 2;
The Audiophile, March 1994: Page 1; Page 2; Page 3;

 

DPA200S

Phono stage to match preamp; half-width case; quite rare.

 

 

Power amplifiers

DPA100S

The first power amplifier. 65W / 8ohms. Uses regulated supplies, takes feedback from the speaker’s positive terminal via dedicated 3-core speaker cable

Review: Very positive and in-depth technical review by Paul Miller
Hifi News & Record Review, October 1987: Page 1; Page 2; Page 3; Page 4;

 

DPA50S

Development of the 100S; fully differential input, four-wire (Kelvin-sensing) connection to take feedback from speakers. Nominally 50W/8 ohms, actually nearer 80W output. Requires Deltec's own 500S or 1000S speaker cable, which is connected via two XLR plugs per channel.

Photos: Inside - overview; Single channel close-up

Reviews: as 50S preamplifier above.

 

DPA200S

Half-width, budget/ simplified version of basic 50S circuit. 50w/8ohms; can be bridged for 200W output. Heatsink capacity insufficient for this usage though!

Reviews: as 200S preamplifier above.

 

 

Integrated amps

DPA Renaissance

One-box amp offering 32W/8ohms, in new 'DPA slab-fronted case. Electronic design simplified somewhat from preceeding amplifiers, but very flexible: push-button source selection, balance...and tone controls!. Reviewed in Hifi World, September 1994;

 

DPA Enlightenment

See 1997 Brochure below

 

 

CD Players/ CD Transports

DPA T1

Based heavily on a re-packaged, re-engineered Marantz CD52.

 

DPA Renaissance CD Player

Integrated player matching the Renaissance amplifier; near -identical to the more expensive Enlightenment (below). Philips CMD12.1 mech, uses DPA's own Current Pulse 1-bit converter. Reviewed in Hifi World, June 1995: Page 1; Page 2; Page 3;

 

DPA Enlightenment Drive

Transport only. Philips CMD12.1 mech, Deltran clock link for DPA dacs, optical and RCA coaxial SPDIF output. Reviewed with the matching Enlightenment DAC in Hifi World, March 1995

 

DPA Enlightenment Player

As above with onboard dac


Update Mar 08 Tom Whelan who built many of these units, commented recently:

"Though the original mechanism for both the Enlightenment and Renaissance CD Players was a Philips, it was a dreadful affair costing $13; reliability 2 weeks after shipment. Though at least 2 still exist. The final CD Player mechanism was a Teac supplied from Germany by George Bruhns (now deceased) German Distributor of DPA. Most Enlightenment and Renaissance CD Players featured DX Processors, but from 1997 onwards they were FPGA based 24 bit Pulse Array."

 

 

Deltec were also one of the very first to realise the benefits of slaving the transport to the conversion clock in the DAC. This is the Deltran link fitted on all their CD transports. Here's the original Deltran press release (19/03/1992)

 

 

Digital to Analogue converters

DPA PDM 1

Deltec's first DAC (11008-89); used the Philips' SAA7320 bitream DAC/ decoder and the analogue stage is based around the DH-0A32 discrete opamps.

 

DPA PDM 1.2

1991 Revision of the PDM to use Philips' SAA7322 bitream DAC/ decoder. Analogue stage based around the DH-0A32 discrete opamps.

 

DPA PDM 1.3

1993 Revision of the PDM to use single Philips' SAA7350 ('DAC7') bitream DAC/ decoder. Analogue stage still based around the DH-0A32 discrete opamps.

Update Mar08 Tom Whelan confirms "The last series of PDM 1 series 2's were PL prefix; these were the most polished; some had coax and optical inputs. PDM 1 series 1 used the SAA7320; early PDM 1 series 2 used SAA 7321 (times 2) and final versions used SAA7350 devices."

 

DPA PDM 2

At the time,an assault on the state-of-the-art - which still sounds superb today. The very first DAC to use Philip's new CD7 chipset, and possibly the most fastidious implementation of it ever. The DAC came in two boxes, with eth digital and analogue sides kept seprate but linked by 6 fibre-optic cables. Unfortunately the AT&T transmitters/receivers used are very fragile and short-lived, and suitable replacements no longer available...

1991 Press Release: Page 1; Page 2;

Technical description: Page 1; Page 2;

Reviews: HiFi World, June 1991: Page 1; Page 2;

Another very positive review by Paul Miller, Hifi News & Record Review, Sept 1991: Page 1; Page 2;

 

Little Bit, mk.1

Half-width case; SPDIF input via coaax (RCA Phono) only. Uses a Yamaha YM3623 input reciever, Philips SAA7350 DAC and simple analogue stage built around NE5534 opamps. Still a great-sounding little DAC

 

Little Bit, mk.1.2

As Little Bit Mk.1; still based on SAA7350 dac but with extensive layout revisions and Deltran output.
Reviews: HiFi World, Sept 1993;

 

Little Bit, mk.1.3

Revised model re-housed in a full-width case derived from the Renaisance/Enlightenment design. Electrically, the Little Bit 3 is based on the Yamaha YAC502 and has optical input.

 

Bigger Bit

One-box DAC in classic Deltec rounded case. Based on lessons learnt in design of teh PDM2, and uses the full Philips 'CD7' chipset (SAA7350 with TDA1547 ) to perform D-A conversion. Still capable of stunning results.
Reviews: HiFi World, November 1991: Page 1; Page 2;

 

 

 

PDM1024

DPA's first implementation of their Current-Pulse Conversion technology: direct bitstream conversion not based on commercial DAC chips

Review and interview with Rob Watts: HiFi World, July 1994:
Page 1; Page 2; Page 3; Page 4;

 

Developments from PDM1024:

 

SX1024

PDM 1024 re-named to bring it into line with the SX/DX denominations

 

DX32

 

DX64

 

SX64

DAC based on DPA's discrete 1-bit current-pulse convertor. Reviewed in Hifi World, August 1999 Page 1; Page 2.

 

SX128

 

SX256

 

SX512

The ultimate DAC, building on development of the PDM (later SX)1024. Multiple offboard supplies, 13 FPGAs, user-adjustable dither, DPA's own Current Pulse D-A conversion technology, and only 30 made(!) - at a preliminary cost of 8000 each in 1997.

Technical development overview (PDF format)

And here are some pics inside one..: Inside - overview; Current Pulse Arrays;

 

 

 

Enlightenment DAC

DAC based on DPA's discrete current-pulse convertor. Very similar to DX/SX32/64 dacs. Reviewed with the matching Enlightenment DAC in Hifi World, March 1995

 

 

Accessories

The Power

Mains RF filter. 6A, 240VAC capacity

Reviews: sidebar in The Audiophile March 1994

 

 

Cables

Solid link interconnects:

 

Slink

Two pairs of solid-core silver-plated wire in Teflon per channel. Characteristic white/green appearance. Deliberately non-directional – cores were drawn off the reel and laid-up in alternating directions!

 

White Slink

As above, white Teflon outer wrapper.

 

Black Slink

Ultimate expression of the Slink: Goretex (perforated Teflon) insulation; overall shield with drain wire, covered in positively creepy-feeling black polyurethane. £300/m 15years ago, and still sought-after today

 

500S speaker cable

For use with 50S power amplifiers. Solid-core Litz speaker cable using Slink interconnect for the feedback connection

 

1000S speaker cable

Basically two runs of Black Slink per side, for use with 50S amplifiers. Expensive!

 

 

Other product literature

1997 DPA Catalogue

The product brochure from the last year of trading.

 

 

Manuals and instructions

DSP50S / DPA50S

Pre amplifier manual: Page 1; Page 2; Page 3; Page 4;

DPA50S

Power amplifier manual: Page 1; Page 2; Page 3;

 

PDM 2 DAC

DAC Manual Page 1; Page 2; Page 3;
Second, expanded version:
Page 1; Page 2; Page 3; Page 4; Page 5; Page 6;


If you have anything we can add to this page for the benefit of anyone interested in these fabulous products, please contact Martin.


Footnotes:

1. Comment by 'NeilR' on Pink Fish Media webforum, 2004.


© 2007 www.acoustica.org.uk (opens new window)


8.07.08: Little Bit 3 information updated.
8.03.08: Reviews added for DPA100S power amp & DPA PDM2 DAC; technical details corrected for Enlightenment CD Transports; Little Bit series DACs
1.07.07: Reviews added for Renaissance products, Enlightenment Drive / DAC; SX64, Little Bit 2 , Bigger Bit, DPA 200s; PDM2 manuals expanded. Many thanks to Neil Robinson and Eran for their assistance!
16.06.07: Substantial update - product list and review links added
07.06.07: Page added.