Well, I just found some Telefunken tubes in an old stereo amplifier in my basement and placed them into my peavey valveking. They are the exact same model (12AX7) but of course they are a different brand. Would I have to bias the tubes. Also i've been thinking about switching my Sovtek 6L6GC's to some JJs, would I have to bias these too?
Quote by GiantRaven
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you could just throw them in and be fine. You'll want a balanced tube in the last/phase inverter position though.

the amp gets the biasing, so yea, when you change those 6L6's get your amp rebiased, JJ's are good tubes IMO.
12AX7 is a pre-amp tube. Pre-amp tubes need no rebiasing when changing tubes I am told.

6L6GC is a Power-amp tube. When you change power-amp tubes, you need to get your amp rebiased.

However, I have a valveking too and it seems you dont need to rebias if you change the power-amp tubes since the amp is a FIXED bias amp. In a way its cool since you dont have to worry about all the re-biasing crap. You cant do it yourself since you can electrocute (sp?) yourself if you dont know what the hell you are doing. And to get it done with a tech, you got to pay money. The downside is that you cannot mess with the tone of your amp by getting a bias pot put into your amp. Anyway ...


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ive got a peavey valveking too. Is it true that it doesn't need biasing because the tubes that came in it are ****
My Gear:

Schecter Hellraiser C-1 FR (EMG 85/81)
Mesa Boogie Stiletto Deuce
LOPO Custom 2x12 (Celestion V30s)
do all amps have phase inverters and if so what are the benefits to having a balanced 12ax7 in that spot