digital control of analog component question...

[Fraser, Colin J]

> -----Original Message-----
> From: jhaible [mailto:jhaible at debitel.net]
> Sent: 13 January 2000 13:57
> To: Fraser, Colin J; synth-diy at mailhost.bpa.nl
> Subject: Re: digital control of analog component question...
> 
> > This gives a smooth 'analogue' ramp, with a precise 
> digitally controlled
> > period.
> 
> ... the latter being the ruin of the analogue sound. Unless 
> you're going for
> a
> 1 osc / voice instrument.

The challenge is to deliberately introduce enough of an error to get the
'warmth' back in a multi-oscillator sound.

Ignoring the precise shape of the ramp, what will the differences be between
a DCO and a VCO ?
The VCO may have a short term frequency jitter - each period varying
slightly either randomly or cyclically; it may be out of tune or have
incorrect scaling, and it may have a long term tuning drift.
All of these are measurable, and therefore should be able to be
re-introduced, if required, to a DCO.
Long term tuning drift is not desirable so I don't want to emulate that.
I intend to experiment with deliberately introduced frequency jitter, and
constant beat rate linear detune.


Colin f