[sdiy] MIDI VCO Control - but not CV?

[cheater cheater]

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

Very good point, Christian!
Wonder how to tackle this problem....

For one thing, you could perhaps have CV inputs into the DCO. This
would easily allow sub-audio-range modulation.

For higher-rate modulation, maybe something could still be invented. I
wouldn't be giving up so fast.

The important question to solve this problem is: In a normal saw-core
VCO, what does the pitch CV change actually? How does that work?

>  If you want to build it nonetheless, you'll need a Midi to CV Module that puts out a hard sync trigger

Exactly what I'm thinking of doing!

Cheers
Damian

On 7/15/08, Christian Bergmiller <cbergmiller at gmail.com> wrote:
> 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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