Through-Zero FM as a Leslie

[Scott Gravenhorst]

don at till.com wrote:
>   From: Haible Juergen <Juergen.Haible at nbgm.siemens.de>
>   Date: Thu, 18 Feb 1999 15:30:06 +0100
>
>   Sonically it means that you just (finally) get all the effects of
>   ordinary linear FM. 
>
[...]
>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.

This may be a naive question...

I've created (IMHO) a nice leslie effect by using 3 VCOs and 
a modulation signal that is copied both below and above ground, 
but of equal absolute value.  The negative mod signal goes to 
modulate the pitch of one VCO, the positive modulation signal 
goes to modulate another and the third VCO is unmodulated.  At
low modulation, the effect is swirly and thick, high modulation
makes an obviously 'out of tune' kind of sound, but there is a
very good usable range for this.

How similar is this to what happens in the scenario Don describes?

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