Fender Twin reverb 1966(Blackface) BIAS ADJUSTING HELP!!

Completed amps from Fender, Orange, Hiwatt, Vox, etc.

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IsraelB
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Fender Twin reverb 1966(Blackface) BIAS ADJUSTING HELP!!

Post by IsraelB » Tue Aug 16, 2011 5:02 pm

Hello!

I just replace all tubes of my vintage 1966 twin reverb, DOES ANYBODY KNOWS What M.A should i set the amp and what amperex per tube???

Or please tell me how to do it if im wrong!

THANKSSSSSSS!!!!

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Janglin_Jack
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Re: Fender Twin reverb 1966(Blackface) BIAS ADJUSTING HELP!!

Post by Janglin_Jack » Tue Aug 16, 2011 5:26 pm

You want to set the bias at 70% of max plate dissipation. For a 6L6 I think the Max is 30w per tube so 70% is around 21w. You would have to measure your plate voltage and then based on that plate voltage.

There are some bias calculators our there that do the math for you. I think this is the equation:

Idle Current = (max plate dissipation / plate voltage) * .7 (70%). Anyhow, you can look up the steps on how to do it.

I think a safe number is around 30-35mA, but to be sure, you really need to measure the plate voltage, etc.

Mike

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