Hey guys. I have a little 13w tube amp that has become really noisy. To clarify, it hisses really badly when powered on but not in use. It does this whether a guitar is plugged in or not, and regardless of what volume it is set on - although increasing the volume does increase the noise. It's like it just has this "standby" hiss now.
There is no EQ on this amp, just a Bright / Dark switch. When set on Dark, the noise is definitely there but it isn't too bad, but flick it over to Bright and it really ruins things. Just hisses like a mofo.
I have tried replacing the two 6v6 power tubes and the two 12AX7 pre-amp tubes but the problem remains. Is this something that happens to amps after a while? Do I need to have the caps replaced or something? The amp is only about 3 years old.
What amp is it? Whenever I've come across his it's usually from the amp design, especially old Laneys. If you've already changed the tubes, there may be something wrong with it.