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RE: KT-88 bias in MB-3045

Posted by Caucasian Blackplate on June 18, 2009 at 15:20:07:

Chris O. posted all the advice you need to find the acceptable range of biasing for your KT88's, but if you have indeed triode wired them, there are a lot of other variables.

1) Was the feedback network altered along with this mod? (Hopefully the feedback resistor went way, way up in value, or was removed completely)

2) What kind of plate voltage are you using? Lowering the plate voltage a bit and running higher current would likely decrease the shrillness you speak of.

If the mod left you with tubes in pentode mode, it is likely just popping open the cover, looking at whether you have one or two cathode current sensing resistors, and biasing the tubes a little hotter.