[sdiy] Module idea - you guys get to work (for me!)

[Magnus Danielson]

From: WeAreAs1 at aol.com
Subject: Re: [sdiy] Module idea - you guys get to work (for me!)
Date: Thu, 13 May 2004 21:35:28 EDT
Message-ID: <4c.2c034267.2dd57c60 at aol.com>

> 
> In a message dated 5/13/04 6:25:34 PM, cfmd at bredband.net writes:
> 
> << > The Moog 921B VCO used this type of approach for its 'phase lock' 
> synchronization.
> > Multiply the signal from another VCO with its own, filter it, and feed the 
> offset back to the summing node.
> 
> Actually, this is a *classic* PLL. The only odd part is the expo-function in
> there, which a normal PLL doesn't have.
> 
> Cheers,
> Magnus
>  >>
> 
> This is very interesting.  Does this method give the same sound as the 
> hard-reset sync that we've all come to know?

No!

> (especially when changing the pitch of the synced VCO -- lots of radical
> harmonics, etc.)  I'm guessing that it  doesn't -

You guessed right.

> and that it has a limited "capture" range, but I'd like to hear from 
> those who have actually heard it.

However, there is another form of richness to be gained here. One is naturally
that of the locked signal tracking along, allowing for ways to additive add
harmonics in the real sense to a signal, but more interestingly when out of
lock/hold range so that you get the beating, where the frequency variation is
certainly an un-sine waveform. The slow locking process of a PLL may also be
usefull. Even when in lock, you can have a slow and resonant tracking, so that
you get lagging response and wobbling frequency as it settles at the target
tone. It's another tool in the toolbox and the 921 implementation isn't all
there is to it!

Cheers,
Magnus