[sdiy] MIDI VCO Control - but not CV?

[Christian Bergmiller]

A digitally hard synced VCO can't be frequency modulated via an analog LFO/VCO.

If you want to build it nonetheless, you'll need a Midi to CV Module
that puts out a
hard sync trigger. A phase accumulator oscillator (for example) can
run in an interrupt routine nicely. search PAO on the net..

Christian

2008/7/15, cheater cheater <cheater00 at gmail.com>:
> Tom,
> I guess what I'm asking about is: how easy is it to modify my
> favourite VCOs (e.g. the MOTM VCOs or the moog ones) to work with
> this? What would I need to look for?
> Not all VCOs use an accumulator design - do they?
> I am thinking it could be very difficult to do with a sine oscillator.
>
> Cheers
> Damian
>
> On 7/14/08, Tom Wiltshire <tom at electricdruid.net> wrote:
> >
> >  What you're talking about sounds like a MIDI-controlled DCO, so all the
> > recent comments about DCOs apply here too.
> >  Sampa's quite right to bring up the amplitude compensation problem. This is
> > the main snag with the typical DCO design, but the problem is by no means
> > insoluble.
> >
> >  You're also right to point out that you'd still need a CV to control the
> > filter. But you're going to need a CV to control the amplitude too, so
> > you're going to have a DAC of some type in there.
> >
> >  It's do-able, but it isn't going to be much simpler or easier. In some
> > ways, MIDI2CV with a high accuracy DAC is more straightforward. But by all
> > means go ahead and prove me wrong!
> >
> >  Just my 2 pence,
> >  T.
> >
> >
> >  On 14 Jul 2008, at 19:13, cheater cheater wrote:
> >
> >
> > >
> > > Samppa,
> > >
> > > I'm only talking about taking existing VCO designs, and modifying them
> > > to work in such a setup.
> > >
> > > Cheers
> > >
> > > On 7/14/08, Samppa Tolvanen <samppa.tolvanen at gmail.com> wrote:
> > >
> > > > On 7/14/08, cheater cheater <cheater00 at gmail.com> wrote:
> > > >
> > > > >  Wouldn't it be *much* easier to make a midi2trigger module, that
> > would
> > > > >  then hardsync the VCOs?
> > > > >
> > > > >
> > > >
> > > >
> > > > If I got You right, it would be MCU based squareware oscillator, eh?
> > > >
> > > >
> > > >
> > > > >
> > > > >  Are there any popular/interesting VCO designs that wouldn't work well
> > > > >  with being synced this way?
> > > > >
> > > >
> > > >
> > > > Sawtooth oscs would be  just fine as long as You don't mind amplitude
> > > >  multiplying/dividing by powers of 2 per octave :D
> > > >
> > > >
> > > >  Samppa
> > > >
> > > >
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> > >
> > >
> >
> >
> >
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