AW: Through-Zero FM as a Leslie

[Haible Juergen]

	>The best Hammond organ sounds I've heard on the Yamaha DX-7 have
all
	>used a patch where several oscillators are mixed together and then
FM
	>modulate a single final oscillator, where the final oscillator is
set
	>to some fixed low frequency, around 1 Hz.

Yes, I remember that from programming a DX-7 (long ago). And I always
thought how nice it might be to go substantially below 1 Hz ... (Stupid
limitation on the DX7 ...)

	>I've always thought this was very clever, using FM not for warping
a
	>basic sine wave but as a chorus-like effect that provides animation
	>and some soft clipping.

I never thought so far, back then. It wasn't much more than trial and error
for me.

	>Have you ever tried this with one of your through-zero VCO's?
	>Running, say, a Wurlitzer through it?

Not yet. There might be problems with the Wurlie's dynamic range, because 
of the implementation of the tru-zero-VCO. It isn't perfectly smooth when
the
modulator amplitude just "scratches slightly" at the 0 Hz border. 
Didn't these DX-7 patches introduce the amplitude dynamics just at this
last oscillator in the signal chain, i.e. the 1Hz operator? 
And it was phase modulation so the modulation index would vary ...
Anyway, I will give it a try !

JH.