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PostPosted: Sat May 29, 2010 9:21 pm 
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Mark IV

Joined: Wed Apr 11, 2007 8:03 pm
Posts: 613
Location: Sayre, PA
So I was playing my TA this evening on the Top Boost selection channel one about 11 Am master volume engaged and all of the sudden the volume starts to fade lower and I'm getting "distortion" (sounds like a pedal when the battery is dying or shorted guitar cable sound). Switched over to the second channel, same thing. Dropped it down to 5 watts and the distortion seemed less. Turned everything off, waited a bit, then back on, all was AOK. I'm thinking that it may be a fluke powertube? What do you guys think?? Thanks!

I plan to call Sweetwater on Tuesday (had it about 3 weeks).

Matt

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Matt D'Ortona

Mesa MKIV
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Marshall Class 5 Combo
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PostPosted: Sun May 30, 2010 9:01 am 
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Mark IV

Joined: Wed Jan 24, 2007 4:11 pm
Posts: 742
Location: NW North Carolina
EL84's are a very good place to start. Regardless it's always a good idea to keep a complete second set of tubes on hand given the quality of todays tubes and the hell they go thru in shipping. That way when a problem like yours occurs you can simply swap them out and know right away.


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PostPosted: Sun May 30, 2010 2:44 pm 
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Mark IV

Joined: Wed Apr 11, 2007 8:03 pm
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Location: Sayre, PA
Actually I usually do keep a spare set around (but hadn't gotten around to snagging a pair of EL84s yet) :oops: .
Thanks for the validation regarding power tubes issues.

Matt

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Mesa MKIV
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I REALLY NEED TO HAVE MY HEAD EXAMINED!!!!


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PostPosted: Sun May 30, 2010 7:03 pm 
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of all the modern tubes, el84s are built most poorly.

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PostPosted: Tue Jun 01, 2010 5:54 pm 
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Bottle Rocket

Joined: Tue Jun 01, 2010 5:52 pm
Posts: 3
Yep...you are losing a power tube :D

I had the exact same symptoms with my TA-15 after one week. Popped in a set of JJs and all is good.

Keith


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PostPosted: Tue Jun 01, 2010 9:07 pm 
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Mark IV

Joined: Wed Apr 11, 2007 8:03 pm
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Location: Sayre, PA
That's reassuring to hear! Sweetwater is sending me out a new pair of Mesa tubes. If they prove tempermental, then I'll go with the JJ's (I'm a tad short on cash at the moment) :roll:

Matt

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Matt D'Ortona

Mesa MKIV
Mesa Subway Blues
Marshall Class 5 Combo
Binghamtone Amps Twin Jr.




I REALLY NEED TO HAVE MY HEAD EXAMINED!!!!


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PostPosted: Wed Jun 02, 2010 10:02 am 
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Mark II

Joined: Tue Jan 27, 2009 11:02 am
Posts: 55
Location: Milford, CT
I've had my TA15 for a little over 2 months and it has had the exact
same problem several times, the latest being during a gig last Sat.
Have tried flipping to Standby, changing modes, channels, etc.
Usually powering off/on corrects the problem, but this time, I had
to change to Normal mode and stay there.
I suspected a tube, but haven't gotten around to changing them yet.
Since it is basically brand new, I was pretty concerned, but after
reading the posts on the EL84 and their poor quality, guess I'll just
try some new ones. Any suggestions on which one to change first
or should they both be changed together?

Thanks for the info!


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PostPosted: Wed Jun 02, 2010 12:18 pm 
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Mark II

Joined: Tue Oct 09, 2007 10:28 am
Posts: 56
Location: Richmond, VA
I had the exact same thing happen to me. It was a bad EL84. I called SweetWater, they got Rich from Mesa on the phone and he sent me two new tubes...no questions asked. I do need to get some spares though.

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PostPosted: Wed Jun 02, 2010 12:19 pm 
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Mark II

Joined: Tue Oct 09, 2007 10:28 am
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Location: Richmond, VA
Oh, and since they sent me a set, I changed them both together.

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PostPosted: Wed Jun 02, 2010 2:09 pm 
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Mark IV

Joined: Wed Apr 11, 2007 8:03 pm
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Location: Sayre, PA
Ditto with the changing both tubes strategy.

Matt

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Matt D'Ortona

Mesa MKIV
Mesa Subway Blues
Marshall Class 5 Combo
Binghamtone Amps Twin Jr.




I REALLY NEED TO HAVE MY HEAD EXAMINED!!!!


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PostPosted: Tue Jul 13, 2010 7:42 pm 
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Bottle Rocket

Joined: Tue Jul 13, 2010 7:29 pm
Posts: 4
I can't believe that the tubes that Mesa choose to use on the Transatlantic are so unreliable.
I have had my Transatlantic for 7 weeks now, I've had the same problems as everyone else.
Power cuts to a low distortion which seems to recover after a quick turn off. I was told by Mesa to try changing the tubes, I changed the tubes and it seemed to be OK for a few weeks, and then the same problem again. I took it to the local authorized service centre and they couldn't find anything wrong. My question is, what good is an amp if you can't rely on it. I used the Transatlantic on a gig last week
and it cut out on me on the first tune, it's not a very secure feeling. Should I have gone for the VOX for half the price???? I have to say, I love the sound (and size) of the Transatlantic, I just wished that it was reliable.


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PostPosted: Tue Jul 13, 2010 8:27 pm 
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Mark IV

Joined: Wed Apr 11, 2007 8:03 pm
Posts: 613
Location: Sayre, PA
I had two of them. The 1st one had the same problem you had, changed the tubes and the clean channel strated sounding "honky" not Vox-y. Sent it back, got a 2nd one which was AOK. I wound up sending it back for a refund because of the lack of an efx loop and reverb (and I tried several pedals). FWIW, my understanding is that EL84s are a very finicky species of tube. Hope that things work out for you!

Matt

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Matt D'Ortona

Mesa MKIV
Mesa Subway Blues
Marshall Class 5 Combo
Binghamtone Amps Twin Jr.




I REALLY NEED TO HAVE MY HEAD EXAMINED!!!!


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PostPosted: Wed Jul 14, 2010 6:24 pm 
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Location: Birmingham, AL
chateauneuf wrote:
I can't believe that the tubes that Mesa choose to use on the Transatlantic are so unreliable.
I have had my Transatlantic for 7 weeks now, I've had the same problems as everyone else.
Power cuts to a low distortion which seems to recover after a quick turn off. I was told by Mesa to try changing the tubes, I changed the tubes and it seemed to be OK for a few weeks, and then the same problem again. I took it to the local authorized service centre and they couldn't find anything wrong. My question is, what good is an amp if you can't rely on it. I used the Transatlantic on a gig last week
and it cut out on me on the first tune, it's not a very secure feeling. Should I have gone for the VOX for half the price???? I have to say, I love the sound (and size) of the Transatlantic, I just wished that it was reliable.


Any amp with 84s is going to have that problem. Espcially a $450 Chinese vox...if you want more reliable 84s, you can spend more money on NOS tubes, but EL84s are designed to be pushed hard and as a result they have always been the shortest lived of the guitar amp power tubes.

If you're gigging a $1000 amp, you ought to have a $25 pair of tubes and a fuse for a backup anyway.

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PostPosted: Wed Jul 14, 2010 6:47 pm 
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Bottle Rocket

Joined: Tue Jul 13, 2010 7:29 pm
Posts: 4
Any amp with 84s is going to have that problem. Espcially a $450 Chinese vox...if you want more reliable 84s, you can spend more money on NOS tubes, but EL84s are designed to be pushed hard and as a result they have always been the shortest lived of the guitar amp power tubes.

If you're gigging a $1000 amp, you ought to have a $25 pair of tubes and a fuse for a backup anyway.

Thanks. Money for the tubes wasn't really an issue. I've already gone through 3 pairs in less than 2 months. I've got to admit this is my first amp using 84s. I got this amp because of the size convenience, I've got a Mark V for any 'bigger' gigs. But popping in new tubes in-between sets doesn't strike me as being convenient. I'll see if I can find any NOS around here and see if that remedies the problem. Does Mesa make them (for warranty reasons)? Thanks for your advice, I'll give it a try.


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PostPosted: Thu Jul 15, 2010 11:14 am 
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Mark II

Joined: Tue Jan 27, 2009 11:02 am
Posts: 55
Location: Milford, CT
Called Boogie about this. After describing the symptoms, they suggested
replacing the 12AX7 in V1 position and not the power tube(s).
They sent me a replacement under warranty. Changed it out, and so far it
seems to be working properly, although I've only done a couple gigs, so I
haven't put many hours on it since. Bought a pair of EL84's to have on
hand just in case....


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