Audible Hum From Integrated Amp


I am getting a low volume but audible hum from my Rogue Sphinx. I also hear volume changes through the speakers ( with no music source of course). I have tried other amplifiers in the system, no hum. Any suggestions on what I might do to eliminate this fairly minor but annoying problem? Thanks .

mysterioso1

I think I'll call Rogue tomorrow..it's not a new unit, so I don't expect much, but who knows. Is it worth replacing the power cord? I'm using the stock cord that came with the unit.

Wait, to be clear, do you mean, the hum volume changes based on the volume control, or do you hear the volume control moving, like scratching, when you adjust it?  The latter points to having a DC voltage where there should not be any.

A humm that you hear changing in volume points to an upstream issue.

Erik - I hear the volume control moving when I adjust it. Scratching , as you said, or ticking is a good description.

OP: That’s probably a leaking AC coupling cap.

The longer you wait the more expensive it might be to fix it.

In tube circuits there’s a high voltage bias on the signal, 100V or more, but the AC component is very small, typically under 10V peak to peak.

There should be a cap before the volume control that removes the high voltage DC so the volume knob and everything after only see the small voltage AC. When the cap breaks down and allows some or all of the DC, the volume knob starts feeling all that voltage, and that’s a bad thing. :)