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Mesa Walkabout Megathread!

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#321
Yea, okay I know it's only been thirty minutes, but I have an update. It has to be related to the preamp. When I crank the gain, the sound gets worse. When I get my hand near the input jacks (and the tube, since they're in the same area) it gets worse. When I don't have a bass plugged in, it's there, but it's definitely worse when there's an instrument plugged into the 'passive' jack. When I plug the same (passive) bass into the 'active' jack it sounds just like it does with nothing plugged in.

Something is definitely loose or broken, but I've inspected it visually, and I don't see anything.

Do any of you amp guru's have any ideas? :help:

Jason
 
#322
JJBluegrasser said:
Yea, okay I know it's only been thirty minutes, but I have an update. It has to be related to the preamp. When I crank the gain, the sound gets worse. When I get my hand near the input jacks (and the tube, since they're in the same area) it gets worse. When I don't have a bass plugged in, it's there, but it's definitely worse when there's an instrument plugged into the 'passive' jack. When I plug the same (passive) bass into the 'active' jack it sounds just like it does with nothing plugged in.

Something is definitely loose or broken, but I've inspected it visually, and I don't see anything.

Do any of you amp guru's have any ideas? :help:

Jason
Click to expand...
Change the tubes.
 
#325
JJBluegrasser said:
Vic, yea I thought that too, so I already did. No change...

Jason
Click to expand...
Hmmm, very surprised. Now it gets into what all you've done to it. You can PM me if you want, not sure I can help, but I can try.

Starting with the last thing you did before the noise showed up...

If you roll off the treble/high end does it change? Is it affected by the EQ?

Does plugging something in change it?

Did you change fans? If so, tell me all about what type, thermistor? Where are the wires routed?

If the lid is off or on does that change it?

ANYthing you can think of or try and do... even if it doesn't get rid of it, if it alters it at all, might be a clue...

Generally these are pretty bullet proof amps... this is VERY odd... tell me EVERYthing you did to the amp, how you did it, and if you had ANY problems or difficulties at all...
 
#326
tombowlus said:
Did you swap out both tubes?
Click to expand...
Yeah, just to be sure, by swap I meant REMOVE BOTH tubes that are in there and put TWO NEW (or at least known good) tubes in. Both those tubes are in gain stages that would be a problem if either one went super microphonic on you.
 
#328
Vic said:
Generally these are pretty bullet proof amps... this is VERY odd... tell me EVERYthing you did to the amp, how you did it, and if you had ANY problems or difficulties at all...
Click to expand...

Yea, I agree. I feel like it's probably my fault. However, the thing has been sealed up since the beginning of December. I've just been playing it. Then suddenly, the other day it started doing this. It was sealed then, now it's apart and still doing it.

I just tried the tone knobs and turning down the treble knob definitely lessens the problem, but none of the other knobs have any effect.

Wait, here's a good one. I just accidentally turned the parametric treble center frequency knob all the way down and the noise is really loud when I touch the knob, but only while it's turned down. Now that's weird.
 
#330
JJBluegrasser said:
Wait, here's a good one. I just accidentally turned the parametric treble center frequency knob all the way down and the noise is really loud when I touch the knob, but only while it's turned down. Now that's weird.
Click to expand...
Have you had the treble circuit update done? That's only supposed to be a problem if the gains are cranked, but maybe something became very sensitive to RFI and is affected by the affect (I believe capacitance) of your body?
 
#332
Yea, I'll call Mesa tomorrow. I just hope I haven't voided the warrenty messing with the fan.

Vic,
The only other thing I can think of is the experiment I did the other day when I hooked up the DI to a separate power and drove some more speakers. I can't imagine that would be related, but you're right, I need to think of everything.

I've been using an EHX english muffin on it recently too.

You know, a friend of mine (not an idoit, he has a really nice tube guitar setup and he knows his stuff) was playing it the other day and he was trying to make it feedback (trying to play it like a rock star). I wonder if he could have screwed something up. Still, it seems like it ought to be robust enough to handle that.
 
#333
JJBluegrasser said:
Yea, I'll call Mesa tomorrow. I just hope I haven't voided the warrenty messing with the fan.

Vic,
The only other thing I can think of is the experiment I did the other day when I hooked up the DI to a separate power and drove some more speakers. I can't imagine that would be related, but you're right, I need to think of everything.

I've been using an EHX english muffin on it recently too.

You know, a friend of mine (not an idoit, he has a really nice tube guitar setup and he knows his stuff) was playing it the other day and he was trying to make it feedback (trying to play it like a rock star). I wonder if he could have screwed something up. Still, it seems like it ought to be robust enough to handle that.
Click to expand...
Using the DI as a line out is what it's for, that's not a possibility unless there's something super odd about the input impedence of the power amp (HIGHLY unlikely).

I'd say if the amp's never been updated and if yer buddy sent the amp into its high freq oscillation, who knows, maybe...
 
#336
Hi Jungle,
No I haven't tried that. Maybe I'll give it a shot tonight.


Just a quick update for everyone... I called Mesa Boogie. Wow, was that guy useless. They were no help at all. They did give me the name and number of a certified shop in Durham, so I called him as well. He wasn't really sure, but he's going to meet me Saturday afternoon, so that's good.

I think I've also narrowed down the problem. I'm pretty sure it's related to that treble center frequency knob. When that knob is turned all the way down, I can make the thing sound horrible either by touching the knob or by touching the wires on the back as well. This is even with the gain turned all the way off. No other permutation seems to make as much difference as that knob.

I guess it's either a loose wire, a bad cap or a bad pot. I'm hoping Artie the repair guy can hook me up...

Jason
 
#337
JJBluegrasser said:
I think I've also narrowed down the problem. I'm pretty sure it's related to that treble center frequency knob. When that knob is turned all the way down, I can make the thing sound horrible either by touching the knob or by touching the wires on the back as well. This is even with the gain turned all the way off. No other permutation seems to make as much difference as that knob.

I guess it's either a loose wire, a bad cap or a bad pot. I'm hoping Artie the repair guy can hook me up...

Jason
Click to expand...
Could also be a damaged component if yer buddy with the guitar sent it into oscillation hard.
 
#338
Wow, sorry you're having problems JJ.

I just need to tell you guys about the positive side of the WA for a moment. Last night I played a casino with the WA head and one EA Wizzy mic'ed thru the PA. This was the best tone I've had in over 30 years of playing! (that I can remember) It didn't have the kind of volume you'd need to play without support, but it sounded awesome!

And now, back to your regular programming.
 
#339
tallboybass said:
I just need to tell you guys about the positive side of the WA for a moment. Last night I played a casino with the WA head and one EA Wizzy mic'ed thru the PA. This was the best tone I've had in over 30 years of playing! (that I can remember) It didn't have the kind of volume you'd need to play without support, but it sounded awesome!
Click to expand...

Nice! Very glad to hear that this combination worked out well for you! :)

Tom.
 
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