Those are for the current limiting in that direction. I don't see how they could affect DC offset.CJ said:we reversed this rev pwr board, most of the transistors have no idle current until signal is applied,
this amp distorts at about half volume so i bet they reduced the gain on subsequent models,
strange they they use emitter resistors in the collector also on the bottom half pwr transistors, this causes an offset and there is no pot to dial it out,
nice amp if you are going for that Sly Stone fuzz bass on Dance to the Music but do not want to use a stomp box,
The designed by HDP Is Hartley himself, drawn by HTC is Hollis T Calvert, another long time employee. That was apparently before Jack Sondermeyer took over the amp designing.CJ said:we re-typed the numerology on this thing and gave it a pdf label,
full props to PRR for predicting the 1.8K - 18 K boondoggle, the diode direction, the Q11-Q9 thing,
1971 design, so this is probably the oldest Peavey that has come in the shop, Peavey started in 65.
and a DC path to groundthere are a few differences in the front end, like the input network and the 680 instead of 1K in the diff amp. and we had left off a few caps that are probably to keep things stable,
weird, the driver stage has class A/B bias but the final outputs nada... Legend has it Hartley had trouble keeping them from melting down and spent so much time on the phone talking to Sondermeyer at RCA, he talked him into joining himlooks like the output section is indeed biased off,
I see three diode drops and three Vbe junctions so class A depends on how hard you hit those diodes with bias current. It looks like a double diode was attached to the heatsink so he was trying to thermal compensate the class A current.we stuck a TIP50 in there for an RCA 40409 pre-driver which comes right after the diff pair , which might explain the cold bias on the other pre drivers,
High closed loop gain attenuates the NF making it easier to stabilize... The quasi complementary output topology adds lag in one polarity of swing that requires a little more compensation, but quasi complementary was widely used by early solid state amp designers out of necessity (poor selection of robust PNP outputs).also, the 1K-1K divider for the NFB seems to have a different takeoff point on one of the resistors, or i might have traced it wrong,
this amp could use some gain reduction,
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