bad preamp tube.

label thief · Jul 19, 2010

i'm getting volume swelling in and out on my mesa roadster head on channel four only. was just wondering which preamp tube is responsible for this, and what i should be buying to replace it.
"Mesa Roadster & Trem-O-verb High Gain Option with 6L6GC'sPrice: 143.75 Description: Need all the gain you can get from your Roadster or Trem-O-verb? This kit uses a matched quad of the JJ 6L6GC's for power, three hand picked high gain ECC83S's for V1, V2 and V3, two standard ECC83S's for V4 and V5 along with a balanced ECC83S for the phase inverter in V6. Scorching lead tones and better note definition!"
is the set i bought from eurotubes if it helps at all

fjk1138 · Jul 19, 2010

Please explain the volume swelling more. Is it a constant fluctuation when it gets louder and softer, sort of like a slow tremelo effect?

If it helps any, I just had a similar problem with Ch 4 on my Roadster the other day, but the volume dipped and stayed lower within 5 seconds of taking it off standby (it did not waver), but the bass and mid knobs also stopped working also. I was told to try swapping V2 and V3 to see if that helped any, so you might want to start there.

By the way, the tube swap didn't help my problem any, and it's currently at a local authorized repair center....who currently cannot hear the problem (yikes).

label thief · Jul 20, 2010

well it sounds like someones pressing a volume pedal down and up when i play. swapped around some preamp tubes V2 with V4, and then V3 with V5 and the problem is still there.

fjk1138 · Jul 21, 2010

I wonder if we have similar problems, but still don't have mine back yet so I cannot say for sure. You should probably call Mesa and ask for a certified repair tech in your area. Good luck and let us know how it turns out.

ElectricTurkey4369 · Jul 30, 2010

I bought from eurotubes and had a preamp tube blow on me within 2 weeks. I told Eddie and he was nice enough to ship another for free. 2 months later i bring my Single Recto to an amp tec to get the FX loop modded and he told me one of my power tubes was dead and it blew the screen grid resistor, so he had to replace it.
I hear great things about eurotubes, mabye i just had bad luck? But im sticking with my local Svetlana tubes for now :lol:

BostonRedSox · Jul 30, 2010

I think your problem has to do with V3 and V5. Check those tubes out. They need to be either non-chinese or non-russian (can't remember which), or you'll have issues. Most Mesa preamp tubes sold now are actually repackaged JJ's, which are said to cure the issue. Those positions must have a more stable tube in them or they'll have problems. I can't recall how new this problem is, or if it affects current Roadsters, but nevertheless it is an issue that you should be aware of. Make sure when you buy new Mesa preamp tubes (or JJ's direct) that they don't say Russian or Chinese on them. They should just read 12ax7. I do believe this will cure both of your issues.

I am sure you may want a more concise explanation as to what I am talking about. All I know is that the older Mesa Russian and Chinese tubes were found to be unstable in those positions in the Roadsters.

Good luck to both of you. As a fellow Roadster owner myself, I can attest to how great and versatile the amp is. Additionally, I can also understand your frustrations with the issues related to this amp and the lack of true technical support from Mesa and their "authorized" techs. These amps can be maddening, but they are worth the frustration.

Peace.