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Old guitar is a tube killer?

Discussion in 'Amp Tech Center' started by turtlevision, Feb 8, 2014.

  1. turtlevision

    turtlevision TDPRI Member

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    I've been using a VOX VT15 for several years and it's generally worked fine. In the last few days I've had two 12ax7 preamp tubes go microphonic on me in this unit, which has never happened before. Just before this issue started, I pulled out an old Silvertone Silhouette from the 60s (?) that I hadn't played in years and plugged it in. Since my wife bought this guitar 10 years ago, it's always had inconsistent and woofy output. Could be a number of things and nobody can get to the bottom of it because the stupid pickups are bolted onto the pick guard and are encased in aluminum. We've always expected there were grounding issues with the guitar.My question is: could this guitar be causing the tubes to go microphonic?

    Sorry, I just noticed this is in the wrong forum.
     
  2. Jimclarke100

    Jimclarke100 Tele-Afflicted

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    In the Vox Valvetronics series, the valve is used of the main signal path to help in the power stage emulations - there are others around here who know rather more about it than me, but I really don't think the guitar will have that effect.
     
  3. soulman969

    soulman969 Telefied Ad Free Member

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    No, the guitar couldn't cause that. Are you sure the tubes are bad?
     
  4. brookdalebill

    brookdalebill Tele Axpert Ad Free Member

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    Tubes are like car tires, they wear out from use.
    Occasionally other things failing in the circuit will "take them out".
    It's just the price of using them.
    Like all tubes, they sound great, till they don't.
    Kinda' why after an eon or two, I quit using any tube stuff.
     
  5. turtlevision

    turtlevision TDPRI Member

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    The tubes are definitely bad, my ears are still ringing from the second tube going down. I bought a new tube today to try to do some troubleshooting. The guy at the guitar store thought there might be a chance that if the guitar has a bad cap that it could do some damage to this preamp tube. He says he's seen it before. Could also be something just gave up in the amp itself, could be flying monkeys. With mercury in retrograde, this could just be one of those odd blips. The truss rod in my wife's Martin won't move, one toilet in my house has failed and I'm waiting for the third shoe to drop. One thing is for sure, if this amp needs fixing, I think I'm done with tubes. I'm hearing some good things about solid state amps these days. It kills me to say that.
     
  6. flyingbanana

    flyingbanana Poster Extraordinaire

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    No..hang in there. Tube amps are awesome. I just bought two from the 60's and they are still working. Hang in there, it'll get better.
     
  7. Frodebro

    Frodebro Doctor of Teleocity Ad Free Member

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    The dude at the music store is, to put it as politely as possible, FREAKING CLUELESS. The tone cap in a guitar simply bleeds some highs to ground.
     
  8. soulman969

    soulman969 Telefied Ad Free Member

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    LOL, throwing out a little technical mumbo jumbo instead of saying actually he doesn't know he tries the let's baffle him with bull**** approach. :rolleyes:
     
  9. Ricky D.

    Ricky D. Doctor of Teleocity

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    Might be a magic spell. You could try sacrificing a goat.
     
  10. Bartholomew3

    Bartholomew3 Friend of Leo's

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    Lightbulbs sometimes do that also.

    If you put 2 in at the same time they may go out within a day or two of each other.
     
  11. Sideways Jaye

    Sideways Jaye Tele-Meister

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    +1
     
  12. turtlevision

    turtlevision TDPRI Member

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    After some fooling around with a new tube last night, it started ringing again. After about 10 minutes, an Am in first position would start the ringing. Seems like certain frequencies are freaking out one of the caps or something of that nature. Other chords were ring free and when I dialed up some serious distortion, it was clear, so to speak. I think it's time to sacrifice the goat.
     
  13. combstone

    combstone TDPRI Member

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    Maybe a loose chassis? Could a vibrating chassis be inducing the ringing in the preamp tubes?
     
  14. Commodore 64

    Commodore 64 Friend of Leo's

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    A made in china practice amp with a starved plate tube gimmick is not very solid grounds upon which to dismiss "tube amps".
     
  15. Berndizzle440

    Berndizzle440 Tele-Holic

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    If you think its the guitar I woukd gladly let it stay at my place ;)
     
  16. songsmith1950

    songsmith1950 TDPRI Member

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    Not the guitar. And please don't give up on tube amps as they are life in music.
    The preamp tubes can easily last the life of the amp, and perhaps the owner as well.

    Tom
     
  17. Tim Armstrong

    Tim Armstrong Super Moderator Ad Free Member

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    This isn't actually a tube amp, it's a modeler that uses a single tube to simulate the dynamics of a tube amp. Very successfully, I think (I have a Vox AD30vt and dig it immensely).

    Sounds to me that there's a problem in the amp itself. Either that or you've gotten unlucky in buying tubes. Considering the often dodgy quality of tubes these days, that's definitely a possibility.
     
  18. songsmith1950

    songsmith1950 TDPRI Member

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    Yep

    You are right about the single tube and it's uses. It is the same thing as the usage in a Tonelab, which I like to keep one or two around. Tubes are not as good as back in the old days but should be better than that unless you are bargain basement in Chinese tubes. Still, you never know, once a tube is shipped and jarred and all. I think you are also right about the problem being in the amp itself. Perhaps a bad solder joint or something like that.
    And yes, the AD30VT is a very nice modelling amp.

    Tom
     
  19. Berndizzle440

    Berndizzle440 Tele-Holic

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    Yea keep the faith! Tube amps are luscious! And that harmony silhouette is a great guitar! Ive got one and its so smooth but rude when ya want it!
     
  20. Keyser Soze

    Keyser Soze Tele-Holic

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    I've read a very reliable tube vendor on another forum say that many new production tubes have out-of-the box failure rates in the mid teens.

    So your problem may simply be poor quality control meeting up with bad luck.

    It could be a problem in the amp - one or more components failing and over stressing the tube.

    The problem is not being caused by any guitar with passive pickups.

    Are you using any effects between the guitar and the amp input?
     
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