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Trouble with JJ 6L6GC tubes... Mesa 400+

Discussion in 'Amps and Cabs [BG]' started by Rockbobmel, Apr 30, 2005.

  1. Rockbobmel

    Rockbobmel Supporting Member

    I sent my tubes back to Eurotubes, and Bob tested them. 2 were bad, so he mached a quad to the remaining 10. So I put them in and the 4 that he sent me showed some white light from under the plates. I could only see that because of it reflecting down onto the lower curves of the glass tube. I cant tell if it was an arcing, but it swelled with the intensity of the note. It was NOT BLUE or PURPLE, it was definately white.I relocated the tubes to different sockets and they did the same thing. The initial sound was fine except when the note decayed, there was a fading distortion. Kinda like a speaker coil rubbing, but only on the note decay. NONE of the remaining tubes acted like this. They were strong and no cherry plating. I called him and he said I was seeing things. I KNOW I am not seeing things cause the rest of the tubes did not even show ANY response to the notes.

    PLEASE help me get this cleared up. Thanks, Bob
  2. James Hart

    James Hart

    Feb 1, 2002
    Endorsing Artist: see profile
    So your tube dealer says you are seeing things...

    What does your tube tech say ;)

    Truthfully, I'd have it to the shop and onced over....get it modded for bias adjustment while there too!
  3. Rockbobmel

    Rockbobmel Supporting Member

    Tube tech said there is definately something wrong. Anyone?
  4. Rockbobmel

    Rockbobmel Supporting Member

  5. All that comes to mind is the bias may be off. Perhaps the old bad tubes wrecked the plates, but I doubt it.
  6. Sidecar666


    Mar 27, 2004
    I don't think that Mesas have a bias adjustment....do they?
  7. They do, I believe.
  8. BurningSkies

    BurningSkies CRAZY BALDHEAD Supporting Member

    Feb 20, 2005
    Syracuse NY
    Endorsing artist: Dingwall Guitars
    Nope. They're fixed bias...It's a mod that's pretty easy to do if you want to add one.

    I'm interested in this too, playing a 400+ myself, and using Bob for tubes. I've been moving towards getting a new set of 6L6's for mine in the next month or so, but this makes me wonder.
  9. Folmeister

    Folmeister Knowledge is Good - Emile Faber Supporting Member

    May 7, 2003
    Tomball, Texas
    I retubed my 400+ with the JJs. No problems encountered.
  10. Ralphdaddy

    Ralphdaddy Supporting Member

    Nov 6, 2003
    Chicago, Illinois
    Same... sounds like a very weird problem. You might take it to a Mesa authorized tech, I did and mine's right as rain ever since. The JJ's are amazing tubes I gotta say, I love my tone and so does everyone else I come across.

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