Not quite sure I understand the goal. Would the desired effect be the same as limiting the potentiometer's range of motion, so that the user could not turn it to the extreme ends? If so, and if you plan to use a digital potentiometer to get recall on the eq settings, you could limit the effective range of motion programmatically while leaving the circuit unchanged.Thanks for the info, that's really useful and in some ways even much more convenient than LTSpice!
Speaking of the shelving circuit: how could I reduce the maximum gain to +/- 12dB while keeping the original frequency response? If it was a standard tone control, I would just increase the 620R & 6.8K resistors. But because of the added low frequency bump/dip it's not that simple. And while I could try all sorts of component values until it kinda looks right, I wouldn't say no if there was some method to the madness
I was able to find three different revisions of the schematics.By the way, I am curious whether 6.8K or 6.2K is the original value of the resistors on the low side of the shelving high/low. I have seen schematics both ways and photos of B205 boards both ways. It makes only a tiny difference to the curves but... Maybe the value got changed at some point during its production?