I re-built a circuit into an old chassis with what I had hanging around . Sounded pretty good until I tried adding a presence control and that's why I am posting . One of the parts I had hanging around was an old Hoffman Stout turret board . It was probably my first or second build and it never really sounded good . More than likely it was my lack of experience in building that was the reason for the poor sound quality. Either way I cleaned up the board and repopulated it with some mods to the layout . Most of the mods are in the pre-amp section that I took from a Matchless design with a 12ax7 parallel triode input . I'll get to that in a little bit . The problem I'm having is in the phase inverter section . In my crude drawings you will see a .01 capacitor connected to pin 7 of the 12ax7 PI . In the "Stout" PI it is in parallel with a 470k resister and then in series with a 47k resister to ground . In the "Matchless" PI the .01 cap is connected at pin 7 and then to ground . Trying to figure out why . I have the PI built like the Stout is built . In my attempt to come up with a presence control I changed it to look like the Matchless PI . As I stated earlier It sounded good until I started messing with it ... Before it was dead quiet and with the change in the .01 cap it became noisy , hissy , not quiet . The Stout PI seems to be different than all of the other LTP types in respect to this .01 cap . Can anyone school me on this ?