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In Reply to: RE: MQ-70 driver for 4 pairs 300B PP?? posted by Tubenstein on April 23, 2016 at 14:59:32
A LONG time ago, mid 1980s, I ( with the help of Bob Goodman and Robert Fulton ) designed and built an eight chassis 450 pound P-P-P 6B4G amp, that could run one to three pairs of 6B4Gs. The " Triode Music Amp ". Front end was all 6SN7GTBs, from a 612 VDC double regulated B+ supply.
I found that for the P-P driver stage, EIGHT 6SN7s in parallel, ( 16 sections total ) sounded best to my ear. The amp was fantastic sounding to me. There was plenty of " moxie " to drive the Finals, and as I recall, each 6SN7 section did 12 mA. of standing current.
It is 2016, and today I'd just use highly efficient speakers and build Directly Coupled, two-stage SET Type 45 amps, making it KISS in design and really thought-out in its execution. After all my years of searching and DIY building, its MY conclusion. High mu driver tube, 70 to 100, 100 mu preferred.
Have fun.
Jeff Medwin
Follow Ups:
Thats 8 6sn7s to drive the PPP 6b4s. Reasonable. Tubenstien wants to drive 8 300bs with a single 6aq8; it ain't gonna work. Although I agree with you about the low power/high efficiency stuff, it does not answer Tubensteins question.
Perhaps a schematic of your PPP 6b4 amp would help. PP4P 300b is what he really wants to build. We should help him with that. I suggested 8 sections of cathode followers, to no avail. Maybe some of your old schematics will help.
Paul,
It was from 1983 and I've looked all over my computer's hard drive, for a schematic, to no avail !! Sorry .
Jeff
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