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Unsolved problem EL34/12AT7/5AR4
Unsolved problem EL34/12AT7/5AR4
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Old 4th October 2008, 03:26 PM   #1
Delphaure is offline Delphaure  Canada
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Join Date: Oct 2007
Default Unsolved problem EL34/12AT7/5AR4

Hi guys,

(I'm a real newbie, so please be indulgent with me )

Someone gave me a SE EL34/12A*7/5AR4 amp.
It sounds quite good but one channel is louder than the other, particularly in the mid-range.

I swapped tubes, swapped and changed the 12A*7; the only one I didn't change is the rectifier.

I interchanged my speakers; I tried the amp with another pair of speakers. I swapped wires and changed them.

I checked soldering, resistors and caps. Everything seems OK. But obviously, there is something wrong. Because one channel is always louder than the other.

The next step I should do is checking transfos. Gosh. I'm not really sure what to do about that...

Before this step, do you think I could do something else, that is obvious for an old DIY pro but unevident for a rookie ?

I know I should have done the schematic, but I didn't

Thanks a lot
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Old 4th October 2008, 07:55 PM   #2
TubeHead Johnny is offline TubeHead Johnny  United States
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Join Date: Jan 2005
Location: The emerald city, Seattle, WA.
How old is the amp? Sounds to me like a resistor or cap has drifted in value, making the channels sound uneven.

Do you have knowledge working with high voltage electronics? If not get a qualified tech to check it out. Voltages inside an amp are deadly!
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