Great stuff, as usual, Brett.S/Hip Ahoy. What's not to love?
For those who may not be familiar with the effect, which actually goes back to the very beginning of synthesizer technology, it's called "Sample and Hold" or simply S&H, (or even just S/H - as in the preset title) and it's random or set level switching on a modulator that is set to modify the filter cutoff. Those who, like me, grew up with Moogs, ARP2600, and huge Roland modular synths will be very familiar with this effect. But it's not one that has been used much as a guitar effect until Zappa did it, as far as I know.
Joe Walsh used a similar effect on this track - listen to it kick in at about the 2'50" mark onwards....