L channel lower output?

[Martin Prothero]

I wonder if someone can help me methodically troubleshoot...

I have a SET I built (see link: PCL86 Piccolo Triode Amplifier) that I am re discovering my love of.
Ive had it stored for about 2 years and recently switched it back in to my main system. When I applied power initially the L channel was dead and after some minutes crackled to life.
I swapped to the tubes over and it continued to work OK but with the occasional crackle noise, so I swapped in a new pair. Things seemed to clear up.

I have been running in a new DAC and have it on for about 2 weeks and now when I listen, it seems the L channel is lower in volume but still clean and clear. The resulting soundstaging is R channel dominant now, with images I know should be central sounding too R heavy.

I tried swapping + and - on L speaker to see if it was out of phase.

I checked the speakers and they are wired OK and I changed the cables over to isolate the fact that it is not them.

Oh and I cleaned my ears out, so its not me

I'm guessing it might be a cap in the power supply or signal path but can someone help me (a complete novice) measure or ascertain where and how to find the fault please?

Many thanks.

Martin

 

[DF96]

Measure DC voltages on L and R channels. Be careful, as high voltages are present.

 

[Martin Prothero]

OK I have a multi meter and I can set it to V. Where do I measure? I am very careful but need to know what to measure and where to put probes...

 

[DF96]

Negative probe on ground/chassis. Positive probe on each cathode in turn. Voltages here should be low enough to be safe, but nearby points may be higher.