Lone Star channel 1 weirdness

[frpax]

OK, so I got this Lone Star. On Channel 1, I'm getting beautiful, big full clean tone. I'm loving life! Then after 5 or so minutes of playing, and without touching any knobs on either guitar or amp, my big full tone goes somewhat muffled, a teeny bit of volume loss, and a bit more gain most noticeable on the B & e (unwound) strings. Then after a minute or two of that weirdness, it goes back to normal! I want as much clean headroom as possible, so I have channel 1 at 100 watts, silicone diode rectifier mode.

Is this a sign of impending tube failure?

[edit] I don't know it it is important or not, but it is a 2x12 combo, 10/50/100 version made in 2011.

 

[The Lo Lands]

OK, so I got this Lone Star. On Channel 1, I'm getting beautiful, big full clean tone. I'm loving life! Then after 5 or so minutes of playing, and without touching any knobs on either guitar or amp, my big full tone goes somewhat muffled, a teeny bit of volume loss, and a bit more gain most noticeable on the B & e (unwound) strings. Then after a minute or two of that weirdness, it goes back to normal! I want as much clean headroom as possible, so I have channel 1 at 100 watts, silicone diode rectifier mode.

Is this a sign of impending tube failure?

[edit] I don't know it it is important or not, but it is a 2x12 combo, 10/50/100 version made in 2011.

Hard to say but most likely! Is it a new amp or do you have it for some years now? I'm asking because if its a new amp you should contact Mesa (warranty) and if you haven't changed tubes lets say the last years it's maybe time for a re-tube.

 

[frpax]

OK, so I got this Lone Star. On Channel 1, I'm getting beautiful, big full clean tone. I'm loving life! Then after 5 or so minutes of playing, and without touching any knobs on either guitar or amp, my big full tone goes somewhat muffled, a teeny bit of volume loss, and a bit more gain most noticeable on the B & e (unwound) strings. Then after a minute or two of that weirdness, it goes back to normal! I want as much clean headroom as possible, so I have channel 1 at 100 watts, silicone diode rectifier mode.

Is this a sign of impending tube failure?

[edit] I don't know it it is important or not, but it is a 2x12 combo, 10/50/100 version made in 2011.

Hard to say but most likely! Is it a new amp or do you have it for some years now? I'm asking because if its a new amp you should contact Mesa (warranty) and if you haven't changed tubes lets say the last years it's maybe time for a re-tube.

I bought it used. It was made in October of 2011. No idea how old the tubes are.

Also on Channel 2, I get an awful squealing howl if I turn the Gain up past 10:00 and the same if I turn the Master up past about 10:00. I'm assuming this is a tube issue as well. Could they be the same tube? I'm not overly anxious to replace every tube at this point.

 

[frpax]

OK. So I was doing some more fiddling around and I discovered that all that howling & squealing on Channel 2 was doing it if I had the reverb switch in the "Bright" position. "Warm" was better. Better still was unplugging the reverb tank altogether!

Any ideas, guys? Bad V4? Bad reverb tank? Could I have had the reverb tank plugged in backwards?

 

[frpax]

I may have solved the problem.

 

[The Lo Lands]

Microphonic tubes. Squealing sounds can happen when preamp tubes go bad or if you use to much preamp gain. For the reverb issue the tube should also be replaced for a new one. I would advise to install a new set of fresh preamp tubes.