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Tea kettle noise from a tube amp.

Discussion in 'Amps and Cabs [BG]' started by GeneralElectric, Sep 13, 2008.


  1. GeneralElectric

    GeneralElectric

    Dec 26, 2007
    NY, NY
    Noticed today I get a tea kettle noise when hooked up to my amp. I play a mesa boogie 400+ into a Berg NV610 and NV 215. It happens when I turn the master volume up. I can have the channel volumes at 0 without a bass plugged in and I still get it. It gets worse when I pull the treble knob out. I have my treble usually set at 7. Also, the higher I turn the treble knob, the higher the hiss gets.

    The higher I turn up the master (even with both channel volumes at zero) worsens the problem as well.

    I've swapped cabinet cables, and I still have the problem.

    I'm guessing its a power tube, due to it being aggitated by the master volume knob. (It doesn't just get louder, it gets worse!)

    Any opinions or suggestions?
     
  2. JimmyM

    JimmyM Supporting Member

    Apr 11, 2005
    Apopka, FL
    Endorsing: Ampeg Amps, EMG Pickups
    When you find out, let me know. My band's guitarist's Marshall 900 combo has the same problem.
     
  3. GeneralElectric

    GeneralElectric

    Dec 26, 2007
    NY, NY
    Gee thanks Jim ;)
     
  4. Sounds like a microphonic preamp tube. If you can turn down both channel volumes and it's still there, then tube V1 is probably good. If it gets worse when the master is turned up, or if it's still there when the master is at zero, it could be one of the preamp driver tubes (V3 and V4). Swap some known good tubes in there and see what happens. You could take V1 and swap it for V2, V3, V4 in turn and if the problem goes away, you know what it is.

    I'd also check this guide out:

    http://www.geofex.com/ampdbug/ampdebug.htm
     
  5. GeneralElectric

    GeneralElectric

    Dec 26, 2007
    NY, NY
    UPDATE: So the tea kettle noise goes away when I have the master volume down.

    I need to buy some new tubes. :(
     
  6. Then it's probably tube V2. Put the V1 tube into V2 and leave the V1 socket empty. If the noise is still there, it's V2 that's bad.
     
  7. GeneralElectric

    GeneralElectric

    Dec 26, 2007
    NY, NY
    How do I know which V is V1 and two?

    Facing the front of the amp, going from left to right?

    Also, I just noticed fiddling with it, that eventually the sound goes away if I leave it on long enough. And sometimes, it doesn't turn on at all. But this is happening more often than not.

    I've got a gig though now, so I'm going to leave the Mesa at home and whip out the SVT. :)
     
  8. JimmyM

    JimmyM Supporting Member

    Apr 11, 2005
    Apopka, FL
    Endorsing: Ampeg Amps, EMG Pickups
    You're just now going to a gig? Sheesh! NYC truly is the city that never sleeps.
     
  9. GeneralElectric

    GeneralElectric

    Dec 26, 2007
    NY, NY
    This is prime time. I'm actually going to shower first, I still got an hour.:p

    Latest I ever went on was 4am. That was a long night. You should come to NY Jim, see the sights, and wear out your fingers.
     
  10. Sounds like a bogus preamp tube to me also. Odd things, those are. Luckily, they're the cheap ones.

    Looking forward to the resolution of your noise.
     
  11. GeneralElectric

    GeneralElectric

    Dec 26, 2007
    NY, NY
    Switching the 2nd tube with the first (and leaving V1 empty) seemed to have solved this problem, at least at my preliminary low volume test. I need another JJ AX7
     
  12. While it is possible that swapping tubes will mask the problem, it is far more likely that you have a bad coupling cap or a cold solder joint to the coupling cap. Mesa's are famous for it.
     
  13. godspeed68

    godspeed68 i'm here for the sound Supporting Member

    Mar 24, 2004
    Chicago, IL
    I realize I'm a bit late, and I'm not 100% sure about V1 vs V4 position, but I do know that I figured it out by taking the bottom part of the chassis off of the amp. It's stamped on the circuit board.

    Hope the SVT stepped up for ya,


    tom
     
  14. Rick Auricchio

    Rick Auricchio Registered Bass Offender

    You must be a weight-lifter! I didn't think anyone whipped out an SVT. Haul it, lug it, move it, wheel it, truck it, drag it, forklift it...
     
  15. GeneralElectric

    GeneralElectric

    Dec 26, 2007
    NY, NY
    I can sorta carry it one arm (when I wedge an end into my side), I didn't know that made me a strong dude.:meh:

    SVT still fails.:p
     
  16. JimmyM

    JimmyM Supporting Member

    Apr 11, 2005
    Apopka, FL
    Endorsing: Ampeg Amps, EMG Pickups
    You should look up Johnk 10 and ask him about the tube replacements he did to his that he said made his VR sound exactly like his old SVT from the 70's.
     
  17. GeneralElectric

    GeneralElectric

    Dec 26, 2007
    NY, NY
    I had gotten a pair of VRs for cheap used, and they always sounded anemic. One of them got stolen recently, so I'm down to one.

    I don't have the money to invest in retubing an amp I seldom use.:p
     

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