[sdiy] Simple bell-EQ

[Neil Johnson]

On Mon, 6 Jul 2020 at 20:11, Rutger Vlek <rutgervlek at gmail.com> wrote:
>
> Hi list,
>
> I’m hoping for some collective wisdom on the following issue. I’m trying to make myself a fancy (analog) guitar buffer with some basic tone controls. I already implemented a switchable high shelf filter (bright switch), and an adjustable 1-pole HPF for cutting bass. Now i would also like to implement a switchable mid-frequency scoop. With a VST parametric equalizer I found a bell-shaped curve with a certain Q and frequency I liked, and would like to implement this with a switch to select a few preset gains (boost/scoop). But I struggle to find a good analog circuit topology that fits my (simple) needs. Google turns up a lot of digital implementations, or way too complex equalizer circuits where every aspect can be controlled, but of which I don’t understand how to set gain, Q and frequency. Any suggestions for a simple bell-shaped EQ for which Q, gain and frequency can be set (and forget)?

On one of the pro audio diy forums I frequent (it's a difficult habit
to kick...) there was a recent thread on 2-opamp parametric EQ
circuits.  See if you can google Crest Century V12.

Neil