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Tube question

Discussion in 'Amps and Cabs [BG]' started by lowendblues, May 25, 2011.

  1. lowendblues

    lowendblues Supporting Member

    Oct 8, 2004
    I just ordered a new GK MB Fusion with the tube preamp. I've been playing for alot of years, but I've never dealt with tubes before.

    I was just curious, and would like to ask the tube devotee's here on the board,,, looking down the road,, how do I know if a tube needs replacing. Or,, if one is giving me problems?
  2. I've had the original preamp tube in my Trace amp for 16 years. Not much to worry about methinks. Everything I've read about preamp tubes is that they just go and go. Power tubes get a much harder life apparently.
  3. It's just a tube preamp.

    If you start getting odd sounds (ringing noises, infinate sustain on certain notes), it could be the tube has gone.

    In reality, treat your amp right and it'll last decades.
  4. JMac- Wiskerface Designs

    JMac- Wiskerface Designs Terror headcase dude

    Jul 8, 2009
    Atlanta, GA
    IME, pre-amp tubes in hybrid amps generally live long healthy lives as they dont do a lot of work.
  5. I got a 1973 vintage 50W valve amp and the preamp tubes may well be original in that also. They are so old their writing has mostly fallen off anyway.
  6. RickenBoogie


    Jul 22, 2007
    Dallas, TX
    +1 forget it even has a tube- should be fine for decades.
  7. Staccato

    Staccato Low End Advocate

    Aug 14, 2009
    ^^^^ This. I haven't looked at the specs of your amp-if you have a standby switch, use it the way it was designed.

    Buy new, or healthy used tubes as a spares. If I can hear a quality difference by placing a spare in the amp, it may be a sign! However, different brand tubes can have different sound characteristics (for lack of a better word).

    It wasn't long after I had two tube amps, that I purchased a good, used Hickok tube tester for this. These testers cost as much/or more than some tube amps. Though, considering how much the Hickoks are in demand, I considered it an item that would hold its value.

    My spares are listed (with photos) in a Word file to keep track, and I've got keep a spare for all sizes/types.
  8. I am going to be the contrarian on this one. Preamp tubes can last for years, if not decades. However, there is no guarantee that the tubes in your particular amp will do so. If they use cheaper tubes, or if they happen to get a lemon in their batch of great tubes (it happens) your tube may last only a few months.
    Basically just listen for excessive noise, or muddiness on certain notes.
    One of the great things about tubes, is that quite often whatever issue you are having is remedied by a tube swap!
  9. Many of the places like TubeDepot will have have suggestions as to tubes to use. In hybrids the tube is there to add "grease" to the signal and seldom is asked to work very hard. Even then, preamp tubes last a very long time. Short of boredom or it getting noisy, one does not mess with it. I suspect it is a pain to get to, sort of a hint they don't expect you to have to access it very often.
  10. username1


    Dec 28, 2005
    alberta canada
    I just got an mbfusion a few weeks back. They ship with jj tubes in them which should be a good long lasting tube. You will hear distortion and noise when they go but chanches are they wont go bad for a very long time. By the way, i think you will be surprised by that head. It is one of the best sounding heads i have played through in a long time and i absolutely love it.

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