I've been looking for a decent tone control preamp and have tried a couple Chinese boards that were awful. I was considering the ESP HiFi preamp but this was deemed a poor design as discussed on a different post.
This is another board kit I found which has decent specs. The balance control was added by me but not sure if that's the optimal location.
This is another board kit I found which has decent specs. The balance control was added by me but not sure if that's the optimal location.
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The balance circuit shorts the output of the opamps at the ends of the potentiometer range, and since the output impedance of an opamp is measured in milliohms (at low frequencies at least), the balance pot is doing nothing but overloading those opamps at the ends of the range. Perhaps the balance pot was originally connected to the wipers of the volume pots, which makes sense.
Modern low-noise design typically uses lower resistance values, like 10k pots, to help push the noise floor as low as possible.
Using a Baxandall volume stage at the input would cancel the inversion of the tone-control stage, but would require a difference balance circuit.
Modern low-noise design typically uses lower resistance values, like 10k pots, to help push the noise floor as low as possible.
Using a Baxandall volume stage at the input would cancel the inversion of the tone-control stage, but would require a difference balance circuit.