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Help!! Tube Question

Discussion in 'Amps and Cabs [BG]' started by Scott_Petersen, Jan 8, 2001.


  1. Scott_Petersen

    Scott_Petersen

    Jul 25, 2000
    I have a Mesa 400+ (bought it new) that I've been playing through for 14 or 15 months, averaging about 4-6 hours per week. Lately I've begun to notice some popping and crackling so I tried all the possible combinations of speaker cales, instrument cables, inputs, outputs, and basses to try to isolate the problem. Nothing killed it, so I called Mesa to get some help. The guy there thought that it sounded like I had a tube going out but that it seemed pretty early for that to be happening.

    Before I drop 200 bucks on new tubes I wanted to see if anyone out there could shed some more light on this for me or has any ideas of what else to check. I guess it would be a bit of a relief if it was just time to re-tube but I would hope that they would last longer than that.

    Any help would be appreciated.

    Scott
     
  2. Sometimes tubes can have dirty sockets. And just giving them a little wiggle in the socket can help. If you find a dirty socket turn off the amp and push the tube in and out of the socket a few times.
     
  3. spoolie

    spoolie

    Nov 30, 2000
    It it very likely it is just ONE tube and a preamp tube at that (less expensive than one of your 12 6L6s). Look on the Mesa Boogie web site, they have a good section on how to diagnose tube problems (by replacing one tube at a time). Good luck, I doubt you will have to retube the entire amp to get rid of pops and noise. If the power tubes are getting weak it's a more gradual degrading of tone and subtle distortion starts creeping in.
     
  4. Scott_Petersen

    Scott_Petersen

    Jul 25, 2000
    Thanks for the responses, guys. I'll keep on it.
     
  5. Scott,

    If the amp is not under warranty, maybe try some contact cleaner in the pots and input and output jacks. I had an amp that was doing the same thing and almost did have an amp tech do a complete once over (resoldering the circuit board, new power tubes, etc. ) and a squirt or two of contact cleaner fixed all. Pots can get dirty quickly and often are dirty when they're shipped.
    BUT, if it's under warranty don't open it up. If it's not, be sure you know what capacitors look like and STAY AWAY FROM THEM unless you know how to discharge them. My guess is that your problem is dirty contact somewhere, either pots or tube sockets. Good Luck!

    Mark
     
  6. Hi there, there has been other ppl here on TB with the same problem. I have a 400+ too, bought it used and never had any probs with it. Perhaps it is a bad preamp tube. Do some searching around for those old threads on the crackleproblem and try to get in touch with the man behind and ask him how he got it fixed.. I cant remember who it was now.. :( Good Luck!
     
  7. I searched around for who it was and I think it was TCollins, do a search for his posts and I think you'll find it. Good Luck! :)
     
  8. TCollins

    TCollins

    Apr 4, 2000
    I just shipped out my Mesa Basis M-2000 TODAY to Central Jersey Music Service for diagnosis/repair. I bought this amp brand new and I have been plagued with popping & cracking noises from the tube side since I have received it. I have tried at least 10 different 12AX7 tubes courtesy of Mesa Boogie...still the problem persists. I called Jersey Central and went over my problem with them and since my amp (new)is still under warranty...off it goes! I am hoping that these people (claim to be the Regional Repair center for Mesa Boogie...see your Mesa Repair info sheets). Mesa tells me that cracking & popping is usually a tube related problem & that some cracking & popping comes with the territory of tube amp ownership....BUT, guys if you could hear what this popping/cracking S.O.B. sounds like, you would be making calls and setting up for repair service too! I had a VERY unpleasant experience with Gallien Krueger's Repair Service which led to me finally getting rid of my GK 2000RB & I'm PRAYING that I get prompt, quality service from Jersey Central! You can be sure that I will let you know how things turn out :)
     
  9. Still that 2000 not working right eh TC? Well at least you have got the stable 400+ to lean back on. I hope I never get any of these probs with my 400+, I really dont want that. But we'll see that day I buy new tubes(if it is a tube problem). :)
     
  10. rickbass

    rickbass Supporting Member

    That's ALL the help they gave to you?!?!? This from the company where Randall Smith says, "no one stands behind their products like we do" and that they treat customers like they would want to be treated themselves??? I wonder how that tech would like to be left hung out to dry if they had your problem with a young Mesa..."duh, sounds like a bad tube."

    Hell, you use your Mesa only 4-6 hours a week. I use my Carvins 3-4 hours a day and I get more customer service from them. And they aren't in the high falootin' Mesa league.
     
  11. ive got mesa 400+ and just retubed it 3 mos ago,i used 12ax7a preamptubes from mesa,( actually jj/tesla relabled)within 2 weeks i lost channel one due to a bad preamp tube. then i got a sound like a fire alarm going off in school, scared the heck out of me! wow, another bad preamp tube. mesa has had problems with these particular tubes and is aware of it. no jj teslas for me! they sent me out a set of ecc83 12AX7Apreamp tubes, different manufacture.....all set now!by the way i use 6L6 str 454 GC svetlanas and really like em,i used to run 427s in the output.....hope this helps....
     
  12. you know its just so odd. when i ran my origional tubes before retubing i had no problems with anything at all except a couple of outputs were rattling. never a preamp tube problem until i put in a new set of preamp tubes. i still have all sets of tubes. the origional tubes to the best of my knowledge seem to have the same internal look as the new ones i put in that were failing. the 3rd set i have yet to put in have a noticably different configuration within the tube. do you think it would be a good test to put my origional preamp tubes back in, they never gave me any trouble. i am now running two of the origional tubes i got with my amp that never gave me any trouble and two of the first new set i got from mesa. the third set remain un touched.is there any check i can perform to see if the problem exists elsewhere as you describe......
     
  13. psycho, i dated my head to be a late 93, early 94 if it matters...suggestions please?
     
  14. psycho, when i lost channel one i found the problem by runningf the amp in the dark with the cover off and noticed the preamp tube closest to a transformer ( had a piece of foam next to it it was so close ) only had one glowing point within the tube, all others had two glowing points, i changed the tube with an origional old one and bingo, channel one came right back. with the fire alarm sound which occured when i was really pushing the ampi saw no noticable difference in the defective tube which was not the next tube in line but the next to last. lookin at the amp from the front. i bad tube , one good tube , one bad tube , one good tube. i cant get it to fail now no matter how hard i try now. mesa was immediatly familiar with this problem when i mentioned a fire alarm sound, they said the only tube that was known to do this sound was a batch of jj teslas.... and sent me out a new complimentary set which i havent put in yet as i mentioned. do you really think the the problem runs deeper........