Happy New Year everybody! I wish everyone lots of good things and happiness!
After many tests and modifications, I should admit that I wasn’t happy with the 3 band EQ results – it either sounded wrong or was unstable at some EQ settings. Turned out making a single Baxandal EQ circuit with three independent frequency bands is difficult to design 😂. I always wondered why classic Ampeg amps had their mid frequency control made as a separate stage – now I probably know why!
So I decided to ditch the mids and only keep two bands, bass and treble. Still thinking about making corner frequencies selectable by the switches, two frequencies per band. This could be useful for different instruments, like moving treble cut-off lower for the bass but higher for the guitar…
This is how my finalized prototype looks now with the mid frequency components out:
And frequency curves (these worked the best with my basses)