Here are some ideas for a 6-channel amp that can be used in / tailored to a number of applications. The overview block diagram: The input gain trim can be one of the following. The one on the left gives about +/- 12 dB of gain. I found it in a schematic for a “Sub-bass processor kit” and someone has posted a scan of it here. It’s a variant (much simplified) of the circuit used in parametric and graphic equalizers, where a bandpass filter is insert in the feedback loop. If only attenuation is needed, and a relatively small amount at that, then a potRead More →