[sdiy] HP from LP ? -> Moog 904B

Michael Zacherl sdiy-mz01 at blauwurf.info
Fri Aug 11 08:07:13 CEST 2017

On 6.Aug 2017, at 14:01 , Andrew Simper <andy at cytomic.com> wrote:

> In the Moog 904B the transistors form a non-linearity which causes the cutoff to increase. This also happens in an MS20 mk1 high pass filter if you construct in "properly" by swapping the positions of the transistors and capacitors.

thanks for the elaborate explanation!
what about a Steiner-Parker filter?

> On 5 August 2017 at 19:18, Michael Zacherl <sdiy-mz01 at blauwurf.info> wrote:
> On 5.Aug 2017, at 7:47 , Andrew Simper <andy at cytomic.com> wrote:
> > I've never got my hands on an actual 904B, nor built/breadboarded one myself, but I have done a dsp model of one and it does sound very cool.
> > The cutoff is modulated upwards when driven,

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