How to indicate Leslie/Rotary speed?
I'm scoring some tunes that use a lot of Hammond organ and go in and out between slow and fast rotary speeds on the Leslie speaker. I want to be able to indicate this. Playback support would be nice, but it's not really a concern for me.
The "guitar vibrato" squiggly line seems like a natural fit, but I'd rather use something formally defined for this purpose rather than reinventing the wheel. Plus if this is transferred to another notation program, I'd want it to import to match their Leslie indicators.
Is there a well-defined notation technique for slow/fast rotary speaker?
Thanks in advance!