[sdiy] MS20 rev1 2 pole high pass

[Andrew Simper]

I've come up with a design for a 2 pole high pass MS20 rev1 style
transistor core filter. Has anyone heard of such a thing before? I'm
guessing so because it was pretty easy to do, just take the ms20 rev1
low pass, swap the transistors for the caps like you do for a regular
sallen key, and also change the transistors to pnp and then feed the
negative control voltage to them. You also need to put a buffer
between the two stages, but other than that the opamp and resonance
side of things can stay the same.

I've not yet built the circuit, but I've done a model of it and made
an audio demo here:

www.cytomic.com/files/thedrop-one-sided-tranny.mp3

For this demo I took the output pre final diode clipper, which is easy
to do in software.

Andy
--
cytomic - sound music software