Here's my take at a Leslie rotary cabinet emu. Since a Leslie makes 'stereo from mono', I made the patch all stereo. Hook up a mono source to both In1-2.
* MultimodeFilter 12dB splits the incoming signal into high and low freq's, emulating the top and bottom speakers.
* Two Biphase LFO's modulate delay time of modDelay, and, inverted, the amplitude, for both L/R and top/bottom speakers.
* Control Smoothers, modulated by j9k's Comparator, soften the transients from Slow to Fast. j9k's Comparator compares the output of the slow/fast switch to an intermediate frequency. When the cabinet's rotation accelerates, it's pretty fast, when it decelerates, inertia keeps up the speed a bit. This makes a more realistic Slow/Fast switching...
Have fun"Daddy, little Jimmy peeing his pants again"