Kaputt Amp head. Advice appreciated!

[Brachabre]

Soooo I've had this Krank Rev Jr Pro 20w head/cab combo for over 6 months. Has worked great until yesterday.

I turned on the head, geared up, pre/powertubes all lit up as usual, but instead of sound, a loud as fuck screeching noise came out of the cab. It happens even if volume is at absolute minimum. It happens on both the Krank and Kleen channels.

Does this sound like blown tubes or circuitry problem? I know it's about time to change the tubes, but I'm new to owning tube amps and a bit naive to want to check the tubes with this terrible noise in case it's a circuitry problem.

Thanks for any tips!

 

[greyskull]

blown valves generally result in either NO sound if it's the power valves, or thin/wierd sound if it's the pre-amp valves...
BUT a screeching could be a microphonic pre-amp valve. BUT if it occurs with the volume off, it could be any number of other things.... takeit to a tech

 

[Brachabre]

Another bit of info. One of the powertubes fires on and off and the screeching seems to be following its sequence...

Will do. Thanks for the input!

 

[guitarklown]

Dude, if a tech is gonna charge you to look at hte amp, and you see that the tube and the noise are in the same sequence, try a new tube first FFS..

 

[Sloan]

Pull the preamp tubes out one by one with the amp on and see if it stops. Note which tube kills the screeching - it's suspect.

 

[Brachabre]

Fixed! So the finnicky powertube apparently wasn't making good enough contact to the circuit board...

Thanks for the feedback. I got learn-ed.