Bias voltage Question

[joek86]

What is the proper voltage range to run El34's and KT-66's?

Thanks........

[Old Tele man]

...depends upon the power supply B+ voltage provided to the output tubes...got any idea what it might be for your amp? with that info, you make a fairly accurate "guess-ta-mate" for both tubes.

[joek86]

I will call Carr today and find out!

[rooster]

Um... if you have a meter to measure the bias voltage, can't you measure the plate voltage with it? And, if you're not too sure about poking around in your amp to measure things like that, don't you think it might be worth the $$$ to have a tech bias it for you, since the amps run over $1K? Not coming down on you, but it seems to me that it would be a safer way to protect your investment.

rooster.

[joek86]

The paperwork with the amp says to bias from 40 -52. there are bias probe ports built into the amp, so it's pretty easy. I will probably have a tech look at the amp, I've got a respected one in my area.
I tried installing a KT-66 HP but the range of the Bias pot would only bring it down to 58, so I did't use it. It was a 5 on GT's hardness scale if that is relevant.

[John Phillips]

Is that bias voltage or mV measured across a resistor? (ie an interpretation of tube current). If you're using built-in bias test points I would guess the latter.

These are not the same thing.

You need to understand what you're measuring to know whether what you're doing is safe for the tubes or not.

[joek86]

It is mV measured across a resistor.....