[sdiy] should I BUILD SOME SYNTHS ???

[harrybissell]

I saw your newer method...  I did a version of the moog ladder with a
vca AFTER the ladder, because I did not want to change the overdrive
characteristics. The CV needed to increase the level during resonance
... but not TOO MUCH once oscillation starts...was a complex issue. the
result was an almost constant amplitude filter. I needed this for my
theremin
rig...where freeing up an extra hand to control volume was not easy :^P

If you think of it... the noise level should not change (much).   At low
resonance
the resonance path contributes nothing to the output, at high resonance it
is
almost wide open, sending a signal which is essentially the same as the
normal
LPF output anyway.

I'll check the TB 303

I don't understand how increasing the gain at the input would give a more
constant
overdrive character ???  I'll have to look for that (c'mere scope...)

H^) harry

Oakley Sound wrote:

> >  As the resonance is increased... the LPF passband is dropping BUT the
> signal from the OTA resonant feedback path is INCREASING...
>
> I did this for my first version of the Oakley SuperLadder. I liked it
> but the one problem was the noise level would increase with increasing
> resonance. The basic idea of tapping the resonance level is also used in
> the TB303.
>
> I now use an extra VCA tied to the resonance CV at the front of the
> ladder. This has the additional advantage of keeping the signal level in
> the ladder more or less constant for more consistent overdrive
> characteristics.
>
> Regards,
>
> Tony Allgood                           www.oakleysound.com
>
> Oakley Modular Synthesisers      Penrith, Cumbria, England