Variable gain op-amp for volume control (vs normal voltage divider pot)

The feedback volume controls offer the best combination of SNR versus gain...that is...they only give the gain they need, so the SNR is always optimum.

Doug Self has examples in his most recent preamp design. Doug attributes the topology to work done by Peter Baxandall.

In this approach, if the wiper goes open, the gain doesn't go to infinite, but it does go to the maximum gain that the stage was capable of, for example, 16 dB.

Akitika GT-101
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