Re: Brunetti Mercury

Posted by Frank_NH on Feb 23, 2016; 12:26am
URL: http://guitar-fx-layouts.238.s1.nabble.com/Brunetti-Mercury-tp25277p28325.html

Hey Paul,

I changed it back to the original 250K as that sounded fine when I tested it last.  But feel free to reduce it based on your tastes.  I mentioned all of my mods in the original post.

As for squealing, I haven't noticed that at all but I didn't try to box it.  Do all the usual things like using shielded input/output wiring.  You can also try a different op amp - it seems to me a rail-to-rail op amp would work well here, but that may not cure the squealing.

Regarding the bias - I keep thinking that the perhaps the best way to handle the JFET bias issue is to use a socket where the pot goes, attach a pot temporarily to the circuit, then when you have it biased, measure the resistance and replace the pot with a resistor.  Much less to go wrong later on down the road.  And its not like the transistors will burn out like tubes!