Marshall JVM 410H noise

[Marshallraw]

Hello,

I have a Marshall 410H that has constant background noise. I have removed all wires at input and effects loop, same issue continues. I have also replaced all of the preamp tubes, but nothing I've tried fixes it. I have attached a sound recording of the noise, perhaps someone else has an idea of what may be causing it.

Thanks!

 

[dslman]

Maybe power tubes, or the bias is off.

 

[tidbit]

My bandmate’s JVM always has a constant hiss. Most evident in the higher gain modes but always present

 

[Marshallraw]

Thanks for replies. I swapped out the power tubes with new ones, the noise persists. I guess I have to take it to a tech to get diagnosis. I’m going to learn how to bias it first and see if that helps.

 

[dslman]

Hope you get it sorted out.