[sdiy] x0xb0x, yay

[jure zitnik]

i don't quite understand the following: the "filter ringing out" is
probably filter feedback oscillation which has much wider frequency
range than the VCO has. particulary it goes much higher than the VCO
(i'll try to analyze both ranges when i get home). i expect the max
filter frequency to be at least 2 octaves above max VCO frequency
(highest note), if not more.

besides that - like i wrote - the filter doesn't track note pitch so
the frequency difference between the VCO note fundamental and the
filter oscillation isn't really important, it differs from note to
note. so there's no fixed ratio between them.

i AM curious what defines that typical TB-303 high-resonance,
high-cutoff squealch, but i suspect it's just a combination of exact
resonance amount, filter distortion and, most importantly, waveform
like it comes out of the VCO/waveshaper. the filter frequency on the
x0xb0x goes high enough i think so that shouldn't be the issue.

jure

On 12/13/06, Oakley Sound <tonyallgood at btinternet.com> wrote:
>  > I mean that at hight res settings the filter rings out at a
> higher pitch as the gain of Q8 gets lower...
>
> Q8 is the transistor in the square wave shaper - do you mean Q18, the
> unity gain follower in the resonance pathway?
>
> I'm playing around with a new Oakley 303 clone prototype next week and
> I'll look into this particular effect.
>
> Tony
>
> www.oakleysound.com
>