the Nait2: converting the phono stage to a line-level input
Ok, we've looked at what can be done to get more-or-the-same out the Nait's performance, now how about adding another input? As standard, there are just three plus the tape loop. For all models of Nait 1 and most of the Nait 2, one of those inputs is a moving-magnet phono input. In these days of line-level sources a common question is - can this be bypassed to end up with three line inputs, as well as the tape loop ? The answer is yes, and very simply. You end up with an easily-restored line level input with phono connectors. Note though the result is not quite the same as the rare-ish NAIT2 CD model, for which the area of the phono stage was re-worked to provide a buffered line input. The hack here only provides an unbuffered input where the source drives the volume pot directly, just as the other inputs already do.
This hack turns out to be quite straightforward and can be done without removing the motherboard from the case, which is a major saving in hassle I can tell you. It will require some small cutters - I have a small pair of old nail scissors for this sort of thing. Alternatively, a soldering iron can be used to heat the affected component legs and pull free from the board if you are deft.
Bits to cut: These are circled in yellow on the large image. Left: carefully cut the legs indicated of the two 10uf/35v red tantalum coupling caps as close to the board as possible. Gently bend the cap back to expose the freed leg. The new link wire will connect to these. Right:Cut the legs and remove the two blue 10uF/50v coupling caps - boggo electrolytics, eek! This step prevents loading-down the line input with the parasitics of the dead phonostage. Right: Also cut and lift a leg on both of the 27R resistors which supplies the phonostage power rail (if you haven;t already done so for the PSU mods). This reduces the drain on the preamp supply - well recommended anyway if you don't use the phono input. These are already cut on mine, hence jaunty angle of affected resistors.
Finally, carefully cut the two legs of the resistors where indicated with the short yellow stripe (resistors are 33K). Bend up the short remaining wire leg of the resistors - this is where the new links will connect to.
Connect two lengths of wire between the input coupling caps and the upbent leg of the cut resistor leads.
That's it! Your Nait now has an additional unbuffered line input, with phono connectors.
You can of course use whatever flavour of coupling cap you wish to play with, it just seemed more elegant to use the nait-flavoured one already fitted. Film types are strongly recommended, in range 3.3-10uF - this has been discussed a lot elsewhere in the Pinf Fish Media forum DIY section. To make space, solder one end directly to the lead out from the phono socket centre pin. Have fun!
Please let us know how things turn out if you try any or all of the above.
© the twisted pair 2004
© the twisted pair 2004