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Hi,
Hopefully someone can help. I am trying to understand the op point used in the L4 output stage, the 250R cathode resistor seems odd to me, with what I assume is about 380v B+ I can't see how the EL34's are not being considerably overdriven?
What am I missing?
Follow Ups:
we actually have a total of 260 ohms resistance on the cathode of the EL34's - The OHMITE resistors that we use come in 250 and 270 values so we use a 250 in series with a 10R - this is actually a good strategy because if there is a problem with the amp then the 10R resistor 1W will blow first and preserve all the other circuitry - otherwise it would take a lot for the 250R 9W to blow!
Yes, I can see the logic in that. However the original question is still there for 260R, with a B+ of 380v or so, I can't see how the EL34 is dissipating less than 30W or so.
I guess, a better question, what is the target current and B+ for the output stage?
can you send me an email directly to audionotekits@rogers.com - thanks Brian
Will do ta.
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