Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: shortfuse on January 07, 2011, 11:34:59 pm

Title: KT88's In a Plexi 50
Post by: shortfuse on January 07, 2011, 11:34:59 pm

Finally received my replacement tubes from JJ Just installed them and turned bias adj all the way down and they idle at 57 - 59 ma.  Do I need to add a resistor or change one out using the 88's.  The first pair I received idled at 42ma and I ran them at 50ma.  Still didn't need to move the adj much at all.  While waiting on the replacements I used a set of KT77's out of my 5E7 and there was a lot of range adjustment.
I thought you could drop Kt88's as a direct replacement of EL34's without modifications?  Help Please.

Title: Re: KT88's In a Plexi 50
Post by: shortfuse on January 08, 2011, 07:59:24 pm

Did some more reading in the library and changed out the 47k for and 82k all is well and working fine.