Mark noise

[Rhoads]

Have got a big problem with my Mark Iv today.
My amp make a BIG fu...ing noise like a Hhhhiiiisshhhh on every channel and it's worst when i use the EQ,
all the volume or gain knob make a big crack when i turn it. When i unplug my guitar the noise still there and when i move the slider of the EQ up and down the noise frequency (the Hish) follows the slider.

There someone have the same problem before ?

 

[screamingdaisy]

Check the preamp tubes. With the amp turned on and making the hissing sound try tapping them one at a time. If one of them makes a lot of extra noise then it's failed internally and needs to be replaced.

If the preamp tubes check out then do the same test with the power tubes.

 

[swbo101]

The couple of times that has happened to me, it was the tubes.

 

[Rhoads]

I swap all the tube but the noise still there... maybe i need a cap job. :?