Mark V:Sudden Uncontrollable Feedback & Subtle Ringing Issue

BrownieD2W · Aug 22, 2011

Hey Guys,

Went on a mini-vacation this past weekend, so I didn't play my Mark V combo for about 3 days or so, came back and out of no where I am experiencing a problem I thought I had gotten rid of.

Basically the feedback on channel 3 has become pretty ridiculous and borderline uncontrollable, and when ever I play any kind of chugging riffs on the low-E string I get this subtle yet very noticeable ringing noise that I can't really place, I mean I can't seem to figure out whats causing it or where its coming from.

I thought I had solved this problem about a year ago when I put an ISP Decimator Noise Gate in the FX-Loop but all of the sudden it's back. Even tried throwing the noise gate in the front just to see if it worked, no luck.

Any ideas on whats causing this and how I can fix it would be appreciated. I really don't know what could have caused it to come back all of the sudden. It was fine the day before I went on my mini-vacation and when I came back all of the sudden I started getting that problem again.

If you guys need any info on my setup or gear or anything I will be happy to provide it. Any help with this problem would be greatly appreciated.

MusicManJP6 · Aug 22, 2011

Sounds like tube rattle making a tube go microphonic. Pretty common to have tube rattle in a combo amp. Some tubes are worse than others. They make tube dampers that are supposed to absorb the vibration and keep the tubes from rattling and stop them from going microphonic (causing feedback).

Here's what I'm talking about:
http://www.ebay.com/itm/8-VACUUM-TUBE-AMP-DAMPERS-EL34-6CA7-KT77-6L6WGB-/370530363245?pt=Vintage_Electronics_R2&hash=item564554a76d

boogieman60 · Aug 23, 2011

Do the tube test...with a pencil...turn on the amp place it on the offending chan. tap the tubes.. the one that is bad will create the sound you are hearing. I had a strange hum in my V..it was a power tube that was vibrating all on its own. when I held it with a glove ( it was hot) duh....the hum would go away. swapped it out...fixed the problem.

BrownieD2W · Aug 25, 2011

Thanks guys.

Sorry I was slow to reply, just been thinking it over a bit. I think you guys are right, I had been suspecting the tubes for awhile now. I think they have been in need of a swap out for a bit, but since this is my first tube amp I have ever owned I wasn't 100% sure.

I think I narrowed down the problematic tube, it seems to remain much cooler than the others as well, not sure if thats an indication of anything or not.

Thanks a lot for the replies, if anyone else thinks of anything I would be happy to hear more suggestions.

Thanks a lot for the link to those dampers MusicManJP6, I am definitely going to look into getting some of those, they look like a great thing to have with a combo amp.

scubasteve319 · Jun 11, 2012

I too am having a large amount of feedback on the 3rd channel. I'll do the pencil test when I get home today to see if there is a bad tube. Kindof a shame since I just had it in the shop for a blown resistor about 2 months ago :x

Thanks for the wisdom

scubasteve319 · Jun 11, 2012

*sorry for the double post*

I have been reading up on Mesa's Mark V manual and from what i can gather if it is a power tube then you will have an odd loud amount of feedback that can only be corrected by briefly switching to standby... however this hum/feedback will come back. Mesa's manual shows how to identify the tube and what to do.

If the tube is a pre-amp tube there can be the microphonic tube noise (ringing/loud tone)... the manual also talks about this. Check it out (page 51-52):

http://www.mesaboogie.com/manuals/MkV_100303.pdf

Not sure if this helps you since this post is very old but for anyone else who is experiencing these issues as am I currently,
Cheers