Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: Mars-Hall on September 24, 2011, 10:10:23 pm

Title: SFSR cathode resistors
Post by: Mars-Hall on September 24, 2011, 10:10:23 pm

I read in the library about removing the large 150 ohm resistors and the 5uf 25v cap across pins 8 of each power tube.  Can there be negative side affects from doing this?  Aren't the components there to battle poor lead dress issues that are common in silverface amps? 

Title: Re: SFSR cathode resistors
Post by: sluckey on September 24, 2011, 10:39:17 pm

Those particular components were not added to compensate for poor wiring. They give you a degree of cathode bias in addition to the fixed bias. Just remove them, directly ground the cathodes, and rebias.