[sdiy] 4-pole SVF theory

[David Moylan]

I found some references a while back on the Rane website, used for a 
crossover:

www.rane.com/pdf/linriley.pdf

Not a complete analysis there, but should get you started.  In the end I 
slogged through the math to understand what was going on.  I'm not at 
home so don't have my notes handy.

On 8/4/11 6:18 PM, Tom Wiltshire wrote:
> Hi All,
>
> Can anyone point me at some good resources for state variable filter theory? I've spent a long time playing with the classic 2-pole, 12dB oct SVF filter, and I think I get that now. So I want to move along. How do I convert it into a 4-pole filter? (without just sticking a second one on the end of the first one!)
> Presumably there are good reasons why you don't see lots of 4-pole SVF filters around, otherwise I'd have thought it'd be the killer synth filter  - LP, HP, BP outputs, independent Q control - cool, no? So what's wrong with it?
>
> Pleez, help me edukate meself!
>
> Thanks,
> Tom
>
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