Re: Fender Bassman and Sunn 200s preamp pedals.

Posted by rocket88 on
URL: http://guitar-fx-layouts.238.s1.nabble.com/Fender-Bassman-and-Sunn-200s-preamp-pedals-tp25184p44856.html

Not really a rule of thumb, but what I’ve found with these preamp builds is typically if you multiply the bias by how ever many times you’re increasing the voltage from 9V. IE if you’re doubling the voltage and the bias at 9V is 4.5V, setting the new bias to 9V should get you in the ballpark, and may or may not need a little tweaking to get it perfect. What I’ve found from my mini amp builds is that since I’m running them at 24V, I keep the ratio of FET bias to voltage and it’s typiclaly spot on, and using trimmers makes it nice and easy to get it where I want.