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Hi folks: Just built this over the weekend and can’t seem to bias it correctly. Measured voltages between ground and pins 2 and 3 of IC2 read just under 4V and adjusting the trimmer makes very little change. It’s also over-loud and the gain control functions correctly only between 7 and 10 o’clock or so. Any advice (voltages to aim for and correct place to measure changes) will be greatly appreciated as always.
Thanks, mybud
Your VB should be the same as the voltage on IC3B pin 7
You’d get half power 4.5v ish at the junction of the voltage divider R21 and 22 then drop a little after R23
I’m not a 100% If R23 would act as a voltage divider with R22 if it did I’d estimate around 3.6v if your power supply puts out exactly 9v
So whatever you get at pin 7 IC3B is your VB less a little voltage drop through components
Post some nice clear pictures so we can have a look you can check your gain pot as outlined here
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