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resident 16th March 2005 08:56 AM

problem with EL84 PP amp
2 Attachment(s)
A friend of mine has build the attached amp from SDS labs .
But it doesn't work. :bawling:
The outputs of the phase splitter are too much different! :eek: Measurements with voltmeter saw as that we have the same voltage at the grid and at the cathode of the phase splitter.
Not the desired 2V that are needed for bias.But around 100mV difference!
An other strange thing is that the first tube works with 0,5mA! :cannotbe:
After all these I'm thinking that the 4K75 at the cathode of the first stage is too big.What do you say?
Any help?

SY 16th March 2005 11:31 AM

That first hole is being run pretty lightly, but 0.5mA is not unreasonable.

What are your measured B+ rails for the first and second stage?

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