Faint "static" noises in my Lonestar Classic...

[Octavarius]

The noise has been there for quite a while: intermittent, very faint (only noticeable when not playing) scratching-like/static noises. They are still there when the Output is all the way down, so it must be something after that stage. Speaker connection is good, and as far as I can remember, it has done this at a different house, so it most likely isn't power-related.

I'm using the amp in 100W almost ALL of the time, and the noises are very faint. Though when I switched to 50W yesterday, the noise became much louder and more "intense", in a way. Same thing in 10W. And very faint in 100W, still. All the power tubes looked good, and nothing extraordinary was happening visually. Then I kept running it in 50W for a little longer, and the noise suddenly stopped. Gone. Haven't heard it since.

This puzzles me! I related those scratching noises to the type you hear really loud when a power tube is shorting/red-plating (arching inside, etc.), only very quiet. The tubes are about 6 months old, and have been used regularly once or twice a week for a few hours.

I'm not completely convinced that it's the tubes, though, but what more can it be? Output tranny? Other internal components?

This hasn't affected the performance, and wasn't really bothering me that much, but I'm just curious if it could be a precaution for something worse to come?

Anyone had any similar experience or knows what this could be? Please share any thoughts!

 

[nemesys]

Mine started doing the same thing a week or so ago. It's definitely a tube, and I haven't bothered to track it down yet, as it just does it a little bit here and there. It will probably get worse over time, this sort of thing always seems to. If it happens with your output control down, that probably narrows it down to your FX loop driver (maybe -- I know the output control is part of that circuit, but I don't know if it is before or after the tube) or PI tube, or the power tubes.

 

[Octavarius]

Mine started doing the same thing a week or so ago. It's definitely a tube, and I haven't bothered to track it down yet, as it just does it a little bit here and there. It will probably get worse over time, this sort of thing always seems to. If it happens with your output control down, that probably narrows it down to your FX loop driver (maybe -- I know the output control is part of that circuit, but I don't know if it is before or after the tube) or PI tube, or the power tubes.

Exactly. However, it stopped doing it after a couple of power mode switchings. Similar to, for the lack of a better analogy, when a pot is dirty and makes some noise, you move it back and forth a couple of times and the noise dissapears. Do you think this could be it? Simply the fact that the tubes weren't in other power settings for a long time (or the output tranny for that matter) might have caused them/it to stir up a bit?

I've eliminated the loop driver to, as the noises were there even with the loop hard-bypassed (with the channel masters all the way down. Could be the PI tube, though...

 

[MusicManJP6]

Might be worth using some contact cleaner on all pots, jacks, and switches. Just to make sure everything has a good connection, ya know?

 

[nemesys]

Do you think this could be it? Simply the fact that the tubes weren't in other power settings for a long time (or the output tranny for that matter) might have caused them/it to stir up a bit?

Could very well be the output tubes. When you change the power setting to 50 watts, the impedance on the tubes changes. When you switch to 10 watts, the bias voltage changes as well. Under ideal circumstances, everything is still within the operating range of the tubes, but a marginal tube could disagree with the treatment.

 

[boogiemon]

definitely a power tube imho. My classic did the same thing till i finally swapped out one of the 6L6's.

g'luck.

 

[Octavarius]

definitely a power tube imho. My classic did the same thing till i finally swapped out one of the 6L6's.

g'luck.

Just wondering, was it the one closest to the rectifier tube?

In any case, how did you find out which one was the "bad" one?

 

[boogiemon]

don't remember but it was a pain in the a** because the noise was intermittent.

definitely a power tube imho. My classic did the same thing till i finally swapped out one of the 6L6's.

g'luck.

Just wondering, was it the one closest to the rectifier tube?

In any case, how did you find out which one was the "bad" one?

 

[jaquetapus]

I actually just had this problem yesterday. [one of those "grrrr stupid me and my tube amps" moments] While the amp was on with no signal playing I just went to each power tube and plinked my fingernail against them until I found the one that made noise. New pair, problem solved!

-dave

 

[Octavarius]

Awesome! I'll try that tomorrow! Thanks! :wink:

 

[polishcomedy]

is it kind of like a crackling sound? I have the same problem, and I just had the amp restored to new, with new tubes and everything cleaned out. the amp guy said he didn't have that problem at all. I'm wondering if it's the power in my room?

 

[Octavarius]

is it kind of like a crackling sound? I have the same problem, and I just had the amp restored to new, with new tubes and everything cleaned out. the amp guy said he didn't have that problem at all. I'm wondering if it's the power in my room?

I know what kind of sound you mean, and it's not that. Mine is just really faint scratching/screeching noises, almost like rubber rubbing against rubber with reverb or something. It's really weird to explain, but in any case, I do not know how, but I recognize the sound as the sound of a power tube.

The crackling sound you mention sounds more like an input jack or cable than a bad tube to me. Clean all your jacks and contact points and try unplugging your guitar and see if it's still there. Also try tapping the power and preamp tubes while the amp is one to see if they make some noise.

 

[Octavarius]

UPDATE:

Second time I've fired the amp up at home since the mysterious dissapearance of the scratching noises the amp made some small amount of white noise after turned on standby, which was gone after a few seconds. The noises are still gone. Tried tapping the power tubes: all quiet. Had a pretty large gig recently with John Scofield and the amp performed and worked fantastic, even at extreme levels! All is good so far.

 

[Mork]

UPDATE:

Had a pretty large gig recently with John Scofield

Very interesting... tell us more Is he still using a Mesa Boogie?

Glad the static noises have gone...

 

[Octavarius]

UPDATE:

Had a pretty large gig recently with John Scofield

Very interesting... tell us more Is he still using a Mesa Boogie?

Glad the static noises have gone...

Yeah, it was a pretty large big band project with music from his earlier "Blue Matter - Loud Jazz era", featuring John himself on a couple of shows. Lots of fun! He's using a Vox combo. He really liked the sound of my Lonestar, though, even though it was set for a bit different kind of tone than he usually prefers.

 

[Telemaster]

change the tubes...