Volume control circuitry for use with a CV expression pedal on a Hammond organ

[Janus303]

Greetings greetings,

I am helping a buddy with his Hammond CV chop in which the built-in volume control has been removed. Currently, he uses an active-type pedal, but the Hammonds output is much hotter than standard line voltage, so those active-type pedals fail with regularity. A passive-type works, but even at max volume the output is too low to overdrive the Leslie, so he can't get that trademark Hammond growl.

My idea is to build an active-type volume control into the organ so that he can use a standard 5V CV expression pedal (CV as in Control Voltage, as opposed to the coincidentally-named Hammond CV) to control it, which he can then also use with his Vk-8 and Nord when he's gigging with those.

With a good ten-fingered chord with all the drawbars pulled out, the Hammond preamp puts out about 7 volts RMS.

I need guidance choosing the proper FET for the job. With all the Hammond chops out there I have to think this has been done before, but not that I can find. It would seem like a worthy project to crowdsource because volume control on Hammond chops is a ubiquitous problem.

Thanks!