Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: J Rindt on August 07, 2017, 05:50:43 pm
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It has been quite a long time since i biased an amp, so i wanted to check.
A guitar amp with 4 Power Tubes...that is a classic Parallel Circuit, right.?
If i measure Resistance from the OT C-Tap to each OT End, and then measure VDC at the same place.... I = E/R.
That will give the the current for Both Tubes...right.?
So if the math says 70 mA...then there is (assuming they are a perfect match) 35 mA flowing in each power tube.
Is that correct.?
Thank You
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> Both Tubes...right.?
Right. How else could it be?
> says 70 mA...then there is (assuming they are a perfect match) 35 mA flowing in each power tube.
No. It could be 70mA in one and zero in the other.
You are coming to the reason we like a small cathode resistor in *each* tube. You aren't messing with 400V, and you get info on each tube.
OTOH, you can just stuff it and play.