And somehow I knew that it would be wrong. I'll change the topic to suit. It still looks like an interesting circuit.This all still doesn't explain why Google doesn't return anything worthwhile for the terms "baxandall equalizer" or "baxandall equalizer design" or any other permutation. Maybe someone has the original paper that he published?
That is NOT a Baxandall eq circuit - it is an active one-tube gyrator type of eq.A baxandall works on having the filter component (most often a capacitor) either in series with an inverting input, or in the feedback path of an inverting amplifier stage - controlled by a single pot:From: http://www.designnotes.com/CIRCUITS/3band.htmThe first opamp is not needed, the second opamp can be substituted with a tube stage.Jakob E.