[sdiy] little phatty question

[Michael Bacich]

On Mar 29, 2006, at 2:42 AM, ニコラス・ケント wrote:

>
> I guess when it comes to doing something unusual with sync there's  
> the Fenix where you can CV control sync "level" - - from no sync to  
> hard sync with soft sync at the midpoint.
>

It's also possible to create a "phase modulated sync" circuit that  
allows you to shift the actual sync point to anywhere in the phase of  
the master sawtooth wave.  You can then use a control voltage to  
dynamically modulate the phase point where the sync occurs.

Typically we use the master sawtooth's reset pulse as the master sync  
signal, but that pulse always occurs at the same phase of the  
sawtooth wave (usually at the peak of the wave).  Phase modulated  
sync lets you make a reset pulse at any point in the master sawtooth  
wave, and lets you dynamically move that point around with an LFO, an  
envelope, or whatever control signal you choose.

I have heard about such circuits, but I've never actually seen a  
schematic or had a chance to hear one in action.  I am very curious  
as to how it sounds.  I fear that it may not be a very dramatic  
effect, especially compared to modulating the pitch of a synced VCO,  
but who knows?  I'm guessing that these circuits use some kind of  
comparator circuit that is similar to our typical saw-to-pulse  
converter, with the pulse output then turned into a fast sync pulse.

If anyone has a circuit for one of these, I'd love to see it.  I  
think there may have been an Aries VCO module that had voltage  
controlled Phase Modulated Sync.  This would have been a module that  
came out near the end of the Aries company's history (when Paul  
Rivera was running the company), and I don't think schematics ever  
got published.
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