Sounds pretty realistic, although it's hardly much better than the Leslie sim in my PSR-S900.

It probably has adjustments to tailor it to your own liking...upper and lower rates...ramp speed etc.

Ian
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Yamaha Tyros4, Yamaha MS-60S Powered Monitors(2), Yamaha CS-01, Yamaha TQ-5, Yamaha PSR-S775.