[sdiy] Another new module: 4 pole multimode filter

[Paul Maddox]

Scott,

>   I am reminded of the Oberheim Xpander/Matrix12 filter, which used the
> cells of a CEM3372 along with a string of transfer function coefficients
> as long as a train (translation: a couple inverting opamps and a pile of
> precision resistors along with analog switches) to provide 15 selectable
> filter models.

ermmm, I thought the Xpander used SSM2040 as the filter chip?
And to get the various stages, as you said, it mixs the outputs of each
'pole' using precision resistors into a 4067 to give the possible filter
options..

Paul