while probing around in the good amp circuits I did notice quite a few of the 100ohm resistors where reading around 70ohms, would output sound quality be effected? should I worry about replacing them all ?
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70 ohms out of the circuit?
It's hard to say whether it's going to affect sound quality. The differential amplifier at the front-end of the circuit can correct for some changes in components but not for everything.
It's hard to say whether it's going to affect sound quality. The differential amplifier at the front-end of the circuit can correct for some changes in components but not for everything.
Nope they where in , out of circuit they are right on dc offset pots are altering their in circuit resistance , any tips on amp bias setting , don’t know if I’m measuring right looks like 690ma off the right leg of the pot Neg probe to ground
I'd set it to with the pots to the lowest bias/idle current (full CCW?) then increase it until you just see a slight increase in idle current. If you're concerned, run a sine sweep across the audio spectrum (at about 1v output) to see if you get any crossover distortion at any frequency.
Thanks for all your assistance in bringing back this beast of an amp , it was definitely just q911 causing all the issues as far as I can tell, I replaced it tonight with an RCA 256808 (BC856B) . Been running good for 20 minutes now , no smoke or anything to note out of the ordinary . I’ll work in the bias settings tomorrow see if I can dial it in with my scope I’m not sure how good the lumi meter can zoom though