[sdiy] SSM2164 state-variable filter

[Neil Johnson]

Hi,

On 15 Aug 2008, at 16:18, Tom Wiltshire wrote:
> Perhaps it is. Roman Sowa says on his page about his filter that  
> it'll oscillate right down to 0.3Hz, which mine doesn't. It won't  
> oscillate without a signal input below about 1.5KHz.

Interesting.  I've got my filter to oscillate over the range 4Hz to  
16kHz.  The lower frequency may be due to component tolerances (I've  
used junk box 220p ceramics for the integrator caps in the prototype!).

> Above that point, the oscillation level increases markedly towards  
> the top of the range. Roman Sowa says his filter oscillates with  
> high distortion above 10KHz, which suggests the level goes up on  
> his too.

I'm sure Ian's on the right track about LF performance.  Something  
more to look into.

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