fender amp bias
Is the Fender 57 Twin amp self biasing?
Just purchased the above amp. The manual says: “Internal Bias pot added, allowing easy substitution of various 6L6 types”. Does this mean that output tubes can be changed without biasing?
No, this is the opposite of self-biasing.
It means that there’s a pot (a knob, whatever) inside the amp somewhere (probably on the back) that you can twist and turn to change the bias of your tubes so that it can match the tubes you’re putting in.
Self-bias means that you put the tube in, and you’re basically good to go. On my Mesa It can switch between 6L6 and EL34′s, which is sweet. Love those EL34′s, very tweedy, very British.
It’s been my understanding that you should not change the bias lightly… in fact, you should be extremely careful with the bias. Research it first before you monkey around with it… and you shouldn’t monkey around with it. If the bias is too high or too low it will shorten the tube’s life. If you ever see anything but a white or blue glow, especially if it’s orange or red, then turn your amp off and lower your bias, at least if you don’t want to fry your tubes. Always use a matched set of power tubes, its the best way to go.
Find a tech who doesn’t work at guitar center and make friends. Ask lots of questions, it’s a good way to learn. Try to get recommendations as far as which tubes to get, and if you even need to screw with the bias at all ever.
Saul
Fender Rhodes Piano Jordan Pre Amp Biasing
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