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????????5150 combo, power tubes and pre amp tubes!!! thanks in advance!!!!!

I was under the impression that Peavey's were auto biasing in the power section-in any case, pre amp tubes don't have to be biased.

Listen to the amp when you´ve made the changes. It´s like quot;don´t fix it, if it´s not brokenquot;.


Originally Posted by adrianListen to the amp when you´ve made the changes. It´s like quot;don´t fix it, if it´s not brokenquot;.

so youre saying that maybe i dont have to re bias ??


Originally Posted by marvarI was under the impression that Peavey's were auto biasing in the power section-in any case, pre amp tubes don't have to be biased.

no they are not auto biasing!!
also where can i find the stock replacements tubes from peavey ?????

IF you´re not using a matching system like GT or MEsa that allows you to select tubes within a specific tolerance, the amp should always be rebiased after a power tube swap if it´s not auto-biasing (which is actually just a fixed bias in most amps)

In other words: if you switch tube brands, you´re rebiasing or rishing damage... again, the exception being auto-biasing /fixd Bias amps such as Mesas and (mk.I) 5150s

JJ's tend to be middle of the road, bias-wise, so you can pop'em in and they'll be fine. I think the 5150's are a fixed bias, and run a bit cold unfortunately, so the JJ's will heat it up just right, tonewise. I highly recommend GT12AX7C's for highgain amps. They'll do a great job of tightening up the preamp gain.

You always need to check your bias, with any amp, to make sure it isn't off the charts. You may get away without doing it for now, but it isn't right. One day you will find an amp that is biased to high, the day you will pull the short straw.

auto-biasing isn't a term, sorry guys, no such thing.

cathode biased = bias usually isn't adjustable, but can be. The amp is able to handle tubes that vary in bias within a range. Think of this as quot;more forgivingquot;.

fixed bias = your bias needs to be checked and adjusted to a certain spec or range.

anyone also? thats know about this?