My Mark V has strange sound... help

[ikebe3120]

When I used Mk V yesterday, amp produced small strange sound "ss~ss~ss~~"
This sound is different from pick up noise
I turned Master and Output all to zero, and not input guitar. But that sound is still existing.
What's wrong with my amp? please help.
Amp's sound is normal, but has extra strange sound.

 

[Rkorn]

Maybe your amp is acting like a radio and is on to the RF requencies...
Maybe some pre tubes...
But with that kind of sound could be the electricity! Make sure you have electricity enough for the amp as well as ground!

 

[Tuna141]

It's probably just a crappy preamp tube. I suggest picking-up a new 12ax7 and then swapping it with tubes until you find the culprit. You can also use the tube and function diagram to try to narrow down the offender.

Hopefully that's all it is (a $10 fix). Good luck.

 

[eudaimonia02912]

Could be a preamp tube. It might also be the power in your house or studio. Has this happened with other tube amps you've played in that spot?

 

[ikebe3120]

That strange sound is irregular and small.
I have another amp(Line6 Spider Valve), but another amp doesn't has that sound.
So is tube's problem or ground?
Has other methods to be test? Now I don't have tube to test.