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Attent. Veteran Mesa Boogie 400+ owners/?

Discussion in 'Amps and Cabs [BG]' started by TCollins, Oct 2, 2000.

  1. TCollins


    Apr 4, 2000
    I just got a brand new MB 400+ about a month ago-tried it out at the dealers before I got -the dealer changed the four AX tubes in the back 'cos it was making a little noise. The noise disappeared. My question is: The amp is making noise again even I am not plugged into it & the amp is off standby. The noise sounds like a slight crackling sound that I would definitely not want there if I was recording but once I start playing through it-it seems to sound fine. Have I run into some more "bad tubes"? Any of this sound familiar to you veteran 400+ owners? Any suggestions will be greatly appreciated!
  2. timv

    timv Supporting Member

    Jun 7, 2000
    Chandler, AZ
    The amp is off standby meaning it is on? If it the same noise that it made before that went away when the tubes were changed i would assume that may me the problem again. If that doesn't work and you just bought it I would have them get it fixed right cause a brand new head should not be having those problems. I guess that shows how the mesa tubes that are tested by their high standards are still not the best tubes. My 400+ never made any noise as you are describing. I got some hum once the filter caps got old and some weird sounds from some bad power tubes but no crackling popping sound. Hope you get it fixed. I would bring it back to the dealer and have them swap those preamp tubes again as a cheap easy possibility. I wouldn't pay for them though if it is new.
  3. TCollins


    Apr 4, 2000
    Thanks Tim!
    The slight crackling noise that I'm getting is when the amp is "on" (standby "off"). Whether or not I'm even plugged into the amp itself. When I'm playing through the amp, you don't really notice the crackling (playing through the amp does not make the problem worse). One question that I have is: Is tube replacement a "frequent event" with ownership of these amps? While it's still under warranty getting tube replacements is not that big of a deal except that my nearest Boogie dealer is about 3 hours away.
  4. Well TCollins, I have played my amp for a year now and never changed the tubes, didnt expect to either. My tubes were not even new when I bought it (used) so I asked for a genuine pair in reserve, just in case. The crackling noise you describe does it sound like frying eggs? The problem might be in the powertubes, try to tap them softly one by one with the wooden part of a hammer or something, when you hit the right one it will act up.. and you know which to change.

    Anyways my real advice for you, since it is such a new amp, is to mail mesas customer service and ask them what to do. They will help you, you should not accept that kind of problem with an amp like that. Ive got the addy for Kevin at customer service department somewhere, mail me if you are interested.

    Ok hope this helps..
  5. TCollins


    Apr 4, 2000
    I called Kevin at M/B yesterday. He said that if it is a chronic problem to let him know. He also said that that the
    B-3 or B-4 tube might be the problem. He mentioned that to
    find the B-3,B-4 tube, you count from the tube nearest the input. I plan to call him back today--they're very busy there. (Also, STILL waiting for the replacement 12AX-7 tubes Mesa is supposed to send me for my M-2000 (WHICH I STILL HAVEN'T EVEN USED YET 'co of the occasional popping & crackling from that unit. Sheesh! I will so glad to get this straightened out. By the way, my 400+ did not make ANY noise at last Friday night's gig--it sounded absolutely AWESOME. I never got the crackling effect 'til I got home & did a little practicing with it. I'm STILL learning about these amps--hope I get it right!
    Thanks for your input!!!
  6. Hmm it really seems strange. Anyway glad you like it. :)

    But I say you have got an unfare share of bad luck dont you think? But, on the other hand, Im sure you will get it sorted out one way or another.
  7. do you guys have suggestions on which tubes to use on the 400+ are 6l6STR427GC tubes interchangable with 5881 tubes?
  8. Rockbobmel

    Rockbobmel Supporting Member

    I just bought a Mesa 400+ used. Te seller says it is 7 years old, and it sat unused for 5. I expected to replace the power tubes because of what has been said about the cheap chinese tubes. The tubes are branded "5881 6L6 Mesa STR 425"

    I lookes at the Mesa site and the tube replacement page said that the STR 425 was Russian. There was another Russian #, and there was a Chinese # STR427 maybe?

    I also downloaded the owners manual, and it says the 400+ comes with the same 5881 6L6 STR 425.

    Do you think they are Sovtek or Svetlana? Any other Russian tubes?

    They sound real good, and I can't se replacing them yet. Especially if they are really Russian tubes.
  9. Big String

    Big String Supporting Member

    Apr 22, 2000
    Northwest Indiana
    I own two 400+ amps. I retubed both because I didn't like the Boogie tubes. I installed Svetlana 6L6GC and pre tubes are 12AX7EH (electro harmonics) I think Mesa might even use those now.
    Anyway they sound sweet man.

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