Hello, I recently built Eddy Bergmans Steiner Parker filter and am having some issues. I haven’t added cv ins or outs yet, so just input output and the filter select switch. I am dealing with a ground hum/buzz sound on the output of the filter. I have checked grounds a million times and everywhere ground should be, it is. What components could cause this phenomena ? I really want to learn these things to make diagnosing less of a literal nightmare.
Check all cables by measuring their continuity. Do not assume that any of them are ok.
The humm points to a grounding issue, and that is most likely a cabling problem. Since the filter sounds OK, you do not need to search for the problem there.