[sdiy] Filter slopes

[Neil Johnson]

Hi Ian,

> Several of
> the pictures looked like bandpass filter responses with different slopes on
> each side. How would I go about doing that? Is the slope determined by the
> gain of the op amp in an active filter? If it's that easy, would it be a
> highpass filter followed by a lowpass filter each with their own gain
> settings?

Olivier's paper has some good insight into how to achieve what you're after:
https://mutable-instruments.net/archive/documents/pole_mixing.pdf

For a practical implementation hunt out the Oberheim multimode filter circuit:
http://www.synfo.nl/servicemanuals/Oberheim/OBERHEIM_MATRIX-12_SERVICE_MANUAL.pdf

See page 4.

Neil
-- 
http://www.njohnson.co.uk