My Herbert is feeding back bad,For no reason!!!

[monkeyking67]

Hi....Im getting feedback really bad from my Herbert...I have changed nothing as far as settings on my amp or rack....I did a visual check on all power and pre tubes and they're all lit....Anybody have any knowledge on why this would all of a sudden happen?? even at fairly low volumes its feeding back!
Any advice/help would be greatly appreciated...thanks

 

[kahawe]

If I am not mistaken that's practically the picture-book definition of a microphonic tube!

 

[Ventura]

If I am not mistaken that's practically the picture-book definition of a microphonic tube!

Bingo.

No biggy OP, just start changing the preamps around. It happens. Just a matter of time for every amp

 

[monkeyking67]

Thanks guys!!

 

[Peter Diezel]

Hi....Im getting feedback really bad from my Herbert...I have changed nothing as far as settings on my amp or rack....I did a visual check on all power and pre tubes and they're all lit....Anybody have any knowledge on why this would all of a sudden happen?? even at fairly low volumes its feeding back!
Any advice/help would be greatly appreciated...thanks

Please turn down the guitar volume and check if
there is already a feedback.

Thanks,
Peter

 

[monkeyking67]

Hi Peter,
No there is no feedback when I turn down my volume knob on my GTR..

 

[bananaladonpcp]

Hi Peter,
No there is no feedback when I turn down my volume knob on my GTR..

so.... what does that tell you? Check the cables? try different guitars? Plug the guitar straight into the amp with no effects in the loop?

 

[Peter Diezel]

Hi Peter,
No there is no feedback when I turn down my volume knob on my GTR..

Please get a new preamp tube V1 and check it out