CS-50 !!

Joachim Verghese jocke at netcontrol.fi
Tue Sep 10 13:45:15 CEST 1996


On Tue, 10 Sep 1996, Haible_Juergen#Tel2743 wrote:

> Now what's so different with the PWM?
> I think the SINE shape of the modulation is the trick! I found that you
> can set a much higher modulation amount and rate before it becomes
> annoying. I tried it at home on the OB-8 (which has, like most synths,
> triangle instead of sine), and I didn't get the same effect. Then I tried
> it on the Modular, and voila !

Yes, that's one thing I learnt on my Maplin synth, whose LFO had sine
and square outputs but no triangular. Vibrato and cut-off modulation
usually sound better using a triangular LFO, but for PWM you've gotta
have sine.

Another thing I like about the CS-series voice architecture is that
you can high-pass (or band-pass) filter the signal, and then add the
fundamental (sine, again) at the VCA stage.

> (2) The filters seem to be a cascade of 2-poles. Has anybody yet figured
>       out what architecture they have? They don't sound like state variables
>       to me ....

Looking at the schems, the way the resistors and capacitors surronding
the filter chips are connected, I'd almost swear it's two 2-pole
state variables in cascade. I wonder what makes them sound different...
the OTAs, perhaps?

-joachim



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