bipolar 303 filter

[Fraser, Colin J]

> -----Original Message-----
> From: Heiko van der Linden [mailto:h.j.vanderlinden at el.utwente.nl]
> Sent: 16 December 1999 08:46
> To: synth-diy at mailhost.bpa.nl
> Subject: bipolar 303 filter
> 
> I read that the filter in the tb303 is bipolar. 
> Does anyone know: what exactly this means ? 

The filter cutoff modulation by the envelope generator is 'bipolar'.
As you increase the filter mod amount, the cutoff is lowered so that the
average cutoff frequency remains about the same.

> how this is done in the circuit? 
> and if this indeed gives the 
> characteristic
> squelchyness the 303 has?

Not entirely, but it forms a significant part of the sound.


Colin f