Conrad Johnson Classic noisy channel.

An aside: odd how hard it is to pin down a minor issue in a new product.

I don't think small signal tube failure at 3 or 4 months is a "minor" issue. Doing some math based on the info given, the tubes in the one channel are going bad after 400 or 500 hours. The normal expectation for such tubes would easily be 10,000 hours and generally much more. His preamp tubes aren't even lasting a quarter of the expected life for a power output tube.

However, I suspect that in the hands of a good tech with proper equipment, the underlying problem would quickly reveal itself. However, it is not a problem easily fixed by the unaided consumer.

Ask a tech to evaluate the MOSFETs. There are two, strapped onto heat sinks, in the middle of the circuit board.

I had my PV15 into CJ twice (in the ’Ed’ years) and they could not find the issue. Said it tested perfectly. Yet the unit emitted constant low rustle like noises from the left channel as clear as a bell.

Finally had a local guy figure it out. He knew just by the noise behavior what it was before cracking open the top panel. Problem, current punches through the MOSFETs. He put in one that are rated higher. The PV15 sounds awesome now. Can't believe I waited so long to sort it out.

The PV10 has a single power supply though, not sure about the classic. The odd part is that it's only happening on one channel.

Later PV models had split power supplies per channel.

Wait, swapping tubes works? Why don't you just swap across sets?? :)

Keep the good one and swap out the noisy one. Am I missing something?