Noise

[Seanboy]

My son just recently purchased a Mark III red stripe that's mounted in an SKB rack / hard shell case. There's a lot of back ground static type noise when the amp is on. I've got a Mark III no stripe, it's dead silent when it's on. What could be causing the noise? How could we go about getting rid of it?

Thanks
Sean

 

[Seanboy]

Replaced the preamp tube in V1, noise is now gone.