Archive of the former Yahoo!Groups mailing list: MOTM

previous by date index next by date
  topic list next in topic

Subject: Re: [motm] Who wants a completely new filter?

From: mate_stubb@...
Date: 2001-08-23

bleep bleeped:
>>>>
hmm. how about a filter that's completely new? so far, all of the MOTM
filters are based on existing vintage designs, which is groovy and all
but... wouldn't it be excellent if in 20 years the chat on analogue
heaven were all about "how do i get that MOTM filter sound in my
quantum uber 3d virtual modular" etc. etc.???
<<<<

I sent Paul a cool unique filter design several years ago, but he's
undoubtedly forgotten about it by now. It came from a design paper in
the SSM databook. It could be generated from the discrete quad OTA
cell design that already powers the 440.

It is....... ta da! a 4 pole state variable filter. Simultaneous LP,
BP, HP, and notch, but with a steeper 4 pole response instead of the
2 pole response in standard designs. In addition, it has a unique
double feedback path: one called Q and one called R.

Q does what you would expect, while R separates the single peak into
two peaks, and controls the spread between them. Allows for
vocal/formant type sounds from a single state variable filter.

To the best of my knowledge, no synth manufacturer ever produced a
filter of this type. How about it, Paul and everyone? Sound cool?

Moe