There, I said it.... To all the non master snobs out there... Let me explain..... I have a rocknrollamps.com JK30r amplifier.... Its an ac30 with a 63 three knob reverb front end... It had no master volume.. While I loved the clean and reverb, I needed some ac30 growl........ I dont like using pedals so how could I get there.... I have a hayseed 30 that I loved using with its master volume... I always heard those amp snobs out there say .... " master volumes suck tone " .... But I wanted to try it.. Well, I had Jack at rocknrollamps.com install a post phase inverter master.... Holy $%^# The amp totaly smokes now.. all the growl I was looiking for is there along with the great clean and reverb... To all you amp snobs out there ...... BLAH !!!!!!!! By the way , my hayseed 30 may be up for sale soon !!!!!!