Roadster Preamp Tubes Keep Blowing

[protest]

I picked up a Roadster head last week at Guitar Center on clearance. When I got it home I was playing through channels 3 and 4 and everything seemed great. Switched to playing 1 & 2 and everything was perfect. Switched back to channel 3 and it was awful. Low volume, very fizzy, lots of bass, and a hiss after I would hit a note.

Narrowed the problem down to V2 or V3, went to the store yesterday and got a new 12ax7 and took out V2 and V3. I saw that V2 was a Russian tube, so I stuck the new tube in V2, and everything was perfect again...until this morning. Same thing happened, switched from channel 2 to channel 3 and the same exact problems occurred.

For reference, in typical GC fashion they couldn't find the footswitch cable, so I'm switching with the rotary control on the back of the amp. I'm not sure if that has something to do with it. Also, I have no extreme settings. My masters are below 12, and my gain below 2 on channel 3 and below just 12 on channel 4. No Eq controls are cranked.

Any ideas on what would cause a preamp tube to blow twice in such a short time period?

 

[TRENCHLORD]

Did you pull all the preamp tubes and check their types?

Make sure there isn't a Russian #2 in any of the cathode-follower positions.
V3 and V4 are the c.f. positions on the standard dual/triples, but I'm not sure on the Roadster.
Somewhere on this forum is a list posted by mesa, but good luck finding it.

Might be easier to e-mail mesa for a quicker response.
That's all I can think of.

 

[protest]

Did you pull all the preamp tubes and check their types?

Make sure there isn't a Russian #2 in any of the cathode-follower positions.
V3 and V4 are the c.f. positions on the standard dual/triples, but I'm not sure on the Roadster.
Somewhere on this forum is a list posted by mesa, but good luck finding it.

Might be easier to e-mail mesa for a quicker response.
That's all I can think of.

Yea I had thought V3 was the problem, but when I pulled V2 I saw it was a Russian, so that was the tube I replaced, and it worked fine initially.

I'm going to call them tomorrow.

Does putting a non Mesa preamp tube in void the warranty? I know power tubes do, but I'm not sure about preamp tubes since there's no need to bias them.

 

[TRENCHLORD]

Did you pull all the preamp tubes and check their types?

Make sure there isn't a Russian #2 in any of the cathode-follower positions.
V3 and V4 are the c.f. positions on the standard dual/triples, but I'm not sure on the Roadster.
Somewhere on this forum is a list posted by mesa, but good luck finding it.

Might be easier to e-mail mesa for a quicker response.
That's all I can think of.

Yea I had thought V3 was the problem, but when I pulled V2 I saw it was a Russian, so that was the tube I replaced, and it worked fine initially.

I'm going to call them tomorrow.

Does putting a non Mesa preamp tube in void the warranty? I know power tubes do, but I'm not sure about preamp tubes since there's no need to bias them.

Not really sure on the warranty thing.
This list (can't really vouch for it's accuracy) says that on the Roadster it's the V3 and V5 positions that must be the standard mesa (jj) 12ax7.
Other than that it really shouldn't matter.
http://www.thestompbox.net/forum/showthread.php?7525-Mesa-preamp-tubes-do-s-and-dont-s



I'd pull them all and give them all a check.
The Russian #2 in V2 shouldn't matter unless it was just dead or microphonic anyways.

When I first got my single rectifier in 08 it came with 3, yes three dead Russian #2 tubes.
One was the V1 and one was the V2 (which should not have caused a problem), and I can't really remember for sure which slot the other was in.
I'm guessing they had a really bad batch and quit using them completely shortly there after.
Needless to say it was covered and replaced with all standard mesa12ax7 (jj), and not a bad tube since then pre or power in 6yrs.

I'm getting ready to order a couple each of the tung and the EH just to try in the V1 slots on a few amps.