Somebody did... They come standard as a part of the SSL 9k board "kit" i believe. -I did the layouts for all 3 boards (preamp, PSU and balance out) to allow for a modularity of approach, possibly adding EQs etc at a later date, (and the pico compressor looks like an excellent complementary 'channel compressor' type of module) so that people could make their own SSL-flavoured channel strips, but for all the 9k preamp boards that have been sold, I've only ever used ones that I've etched myself... perhaps one day I'll get a set of the black-market-available ones and see how they stack up. :wink:
The prototype for the PSU was done on veroboard and works well... The 2 or 3 I've buiilt since them have been home-etch affairs, with less than pristine edges to the boards. -I keep meaning to re-lay the board out, with pads for series resistance, and all three regulators aligned along one edge, for ease of heatsinking/board mounting
If course in addition to the line regulation question, there's also the question of true sine distortion, which will influence the exact peak-to-RMS relationship, shifting slightly from the usual 1.414 relationship... In the end you can make a choice between cool regulators (if your wall power is not prone to droop) and better drop-out protection in case of droopy power, at the expense of regulator power dissipation (in the form of heat).
A 16-0-16VAC secondary transformer is not a bad compromise to get 15V, and should be reasonably sag-immune, without getting overly hot. Go up if you're worried about sagging wall voltage, down if you're worried about heat.
Keith
