Archive of the former Yahoo!Groups mailing list: MOTM

Creating delayed vibrato with envelope and VCA is ok - many
synths do this. But there is one method I like better: That's the way
it's done in Roland's Vocoder Plus.

There you have a double-T type sine wave oscillator which is
damped such that it cannot oscillate. When a key is depressed,
a variable delay is started, and after that delay a transistor switches
the sine oscillator to being slightly undamped. So it starts oscillating,
amplitude building up in a "natural" way until it reaches a point where
nonlinear feedback prevents it from further growing.
Is this the same as an ordinary LFO, gated with an exponentially rising
envelope ? Maybe so, but I gave not made in depth comparisons so
far. I have built it once, as part of my JH-720 performance synth, and
I like it very much. In a way it's less flexible than a full blown
envelope / VCA / LFO solution in that you don't have extra control
over the rise time (which is coupled to the oscillator's own frequency).
But then again this "natural" coupling of rise time and modulation frequency
is part of the increadibly "natural" feel of the whole circuit. (And you
still
have the delay time fully variable). And the sine wave is very pure - you
cannot accidetially start to gate it open other than on it's zero crossing.

I for one prefer it to the "ordinary" solution by far: I have them both side
by
side in the JH-720, and I'm always using the "Vocoder Plus" option.

So what about a dedicated MOTM Delay Vibrato module ?

JH.