viewtopic.php?t=4576
basically the same circuit topology, but with 12VAC filament operation, and a "split" power supply, so that each channel gets its own CLC filtering, beyond the shared, up-front CLC filtering. I also bypassed all the major electrolytics with MKP and film caps, this makes a dramatically noticeable improvement in the HF response, as it serves to effectively redice the caps' ESR and ESL. For some reason, I did not need this with the Transcendar OPTs, but the James' really needed this in order to sound
their best, otherwise I found them a bit flat and dull sounding for the upper octave's response.
PA-774 power trannie, two Hammond chokes, and a pair of James 3.5K OPTs, and another C354 choke located under the chassis. Another of my "standard" Hammond 12 X 10 X 2 inch chassis, one of the last few left in the inventory.
Cathode resistors are 880 ohm, 25W Dale "heatsink" mounted under the chassis, This was the appropriate resistance value for the 370VDC B+.
Driver stages are my usual 12AT7 SRPPs, with 1K RA and RK, operating at appx 2.4 ma.
Front:
Under:
That's an ST-35 PSU aftermarket power supply board, I have several of these, for three future "Original" Dynaco ST35 restoration projects.
The "extra" fuse holder will eventually be insserted into the PSU after the rectifiers, and before the first cap, but I have to do some minor PC Board surgery to accomplish that...
/ed B
