Mesa Transatlantic issue (vid inside)

[imc2111]

I'm having issues with my brand new Mesa TA-15. It starts working normally and then it starts sounding distorted and unmusical. I don't have much experience with tube amps, I would appreciate any input on this case.

Video: http://www.youtube.com/watch?v=MWX_GxlbliI&feature=youtu.be

 

[Hollis]

I would say 99.9% it is a bad tube. Do you have a replacement preamp tube(12AX7)? If not, go buy you one or two. Replace each tube one at a time until you find the culprit. If it is not a preamp tube, it will be a Power tube(EL84). Buy you a matched pair and replace. Preamp tubes are much cheaper and are more likely to fail, so start there. Let us know what happens!!

 

[knotts]

Probably a tube. Mesa warranties the tubes for 6 months from the date of purchase. If you're in that window it's covered.

 

[imc2111]

Ive been experimenting a bit, put it on 5 watt mode (where it ony uses 1 power tube), and it worked perfectly, used it no problems for an hour. Switched to 15 watt mode, and in no time the issue came back. Does this mean its a power tube?

 

[talltxguy]

Sounds like a bad preamp tube to me.

 

[J.J]

It is almost certainly V4 (the driver tube) or one of the power tubes. Those tubes are also the hardest working tubes in the amp.

 

[imc2111]

What should I try replacing first? Power tubes or the preamp tubes?

 

[J.J]

Assuming your tubes are outside the 6 month warranty, I'd start with V4. Still, if you have to go a get some tubes you may as well get a pair of power tubes as well. Having a spare set is a really good idea.