From ozmusicman88@internode.on.net Mon Jan 31 13:39:12 2011
Subject:[Hammond_xk-3] Re: Harmonic Beating with Vent and XK3c???? NEW VIDEO SHOWING PROBLEM

I think I can hear what you are referring to, although I'm not sure whether it is abnormal or unacceptable. I think that there is normally some modulation caused by the difference between the speeds of the two Leslie rotors (whether a real Leslie, an internal simulator like the XK3c's or an external one like the Ventilator), and that some further modulation is introduced, at yet another speed, caused by the differences between the Leslie rotor speeds and the chorus vibrato speed.

For example, if the upper and lower rotor speeds are .1 Hz apart, then there will be a .1 Hz modulation, which will sound like a slow phase shift, the depth of which will depend on which notes you play and which drawbars you use (i.e., how much of the overall sound ends up going through both rotors around the crossover point). If you add chorus vibrato another .1 Hz faster or slower, then there will be a further, more complex modulation caused by the interaction between each of the rotor speeds and the chorus vibrato speed.