I have had this very sophisticated SET amplifier with 520B valves on the output for a few years now; recently I noticed a unusual distortion between 5k and 12k that was not present before. Neither is the distortion in three other amps I have so I don't think it's related to the AC line. Nothing else change in the amp's sound that I could tell.
If it is a bad part in the amp, what are the first suspects? cap, resistor, tube?
If it is a bad part in the amp, what are the first suspects? cap, resistor, tube?
I have tried different tubes and the problem persists.
The amp was made in Denmark by J. Nielsen. But the designer has no idea what could be the cause.
I also thought it could be the PS caps, especially considering the number of 150uF caps he uses in series for the B+ filtering. I think there are 24 of those caps in series... Checking that will be a major work.
The amp was made in Denmark by J. Nielsen. But the designer has no idea what could be the cause.
I also thought it could be the PS caps, especially considering the number of 150uF caps he uses in series for the B+ filtering. I think there are 24 of those caps in series... Checking that will be a major work.
I have tried different tubes and the problem persists.
The amp was made in Denmark by J. Nielsen. But the designer has no idea what could be the cause.
I also thought it could be the PS caps, especially considering the number of 150uF caps he uses in series for the B+ filtering. I think there are 24 of those caps in series... Checking that will be a major work.
Just a thought,
Have you checked the bias of the O/P tubes? also bias voltage and B+ supply voltage + ripple? Can you direct us to a schematic it might be easier to give some more information..
Regards
M. Gregg
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