Fezter valve

[nopainkiller]

I built this circuit and it sounds great
http://www.runoffgroove.com/fetzervalve.html

Does what it says it does, but I was wondering what raising or lowering the voltage trimmer would make the thing sound like. Only reason I'm not experimenting, is cuz it was so hard to get it at 4.5 volts. I think my trimmer was audio log or something!!