Dampeners to reduce tube microphonics?

Discussion in 'Amps and Cabs' started by Ron, Sep 30, 2006.

  1. Ron

    Ron Supporting Member

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    I've got some preamp tubes that are the cat's meow in one particular rock amp, but they are slightly microphonic and can begin to self-resonate. Their microphonic behavior is part of what makes them great in this amp - very edgy with a borderline psychosis when the tube itself begins to participate in the sound in this way.

    I'm wondering whether someone make a doughnut to fit over the glass and dampen the tube resonances. I know you can use heat-shrink tubing, but these need more inertial mass to keep them in bounds, but still exhibit the right amount of "controlled" microphonics.

    Who makes such dampeners and where do I get them?
     
  2. rockon1

    rockon1 Member

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  3. Ron

    Ron Supporting Member

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    Thanks for the pointer. After I posted, I thought of the exactly same thing! Using silicone-based rubber makes sense for the heat involved.
     
  4. Timbre Wolf

    Timbre Wolf GoldMember Supporter Gold Supporting Member

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    I use some of those tube dampers, bought from the same eBay seller. I use them on 12BZ7s, which are taller-glass 9-pin preamp tube that I use as a sub for 12AX7 (not exactly the same, but it works as if). The length of the tube makes it more prone to vibration and microphonics, and I've had several 12BZ7 become unusable due to microphonics.

    The short of it is that the dampers are (or seem to be) keeping the microphonics at bay, so far. But maybe I have a more robust tube now. I've been using the rings about 5 months.

    The principle seems sound: reduced mechanical vibration by increased mass.

    - Thom
     
  5. HeeHaw

    HeeHaw Member

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    I witnessed the rings make microphonics worse on an amp. I think the rings are just "snake oil".
     
  6. mc5nrg

    mc5nrg Supporting Member

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    I trashpicked a 50's era open reel -one of the metal tube covers was unusually heavy with a thicker top that weighed like it had a lead slug in it.I didn't pay enough attention to note which tube it came off of but my guess is that it was perhaps meant to reduce microphonics.Experts?
     
  7. Tuberoast

    Tuberoast Silver Supporting Member

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    I have a Vibroverb w/ 15"SRO speaker, whenever I crank it the output tubes would exhibit micro tendencies (regardless of the OT's). I put the rubber rings on them and the problem was gone....that's my experience
     
  8. Blue Strat

    Blue Strat Member

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    Try it and let us know. There's no substitute for experience.
     
  9. TDJMB

    TDJMB Gold Supporting Member

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    My Alessandro English has a band of rubbery stuff about 1.5" wide around one of the preamp (6SL7 Octal) tubes. Don't know why.
     
  10. rockon1

    rockon1 Member

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    Nope, not snake oil.Recently grabbed some Viton o-rings from work to try on a microphonic long plate Mullard. They workd well! I can put as many as I want on too. The o-rings cost next to nothing BTW. I do have some silicone based ones-not as many but I dont think its necessary. Besides the Viton ones can be replaced if they get dry.:AOK
     
  11. dognmoon

    dognmoon Member

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    I bought two for my 12ax7's and two for my el84's. I paid $70 for the four of them. If you're interested, pm me. I'm not looking to get more than $35 for the set and I'm not using them.
     
  12. rockon1

    rockon1 Member

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    Its amazing how inexpensive these orings really are! Most of the ones at work(tranny builder here) are Viton and rated up to a few hundred degrees but even the silicone ones are cheap as dirt.:messedup
     
  13. Terry Hayes

    Terry Hayes Member

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  14. Miles

    Miles Member

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    What about tom's tube tamer for the Peavey classic, does it work?
     
  15. uncle looie

    uncle looie Member

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  16. rockon1

    rockon1 Member

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    That is designed to reduce tube "rattle" in the El84's in the Classic 30.
     
  17. stratovarius

    stratovarius Supporting Member

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    I have an amp that has the V2 (6SL7) socket mounted on an isolation plate. I think the manufatcturer omitted such a device on V1 because the additional height would mean that taller versions of that tube would hit the speaker. I think I'd like to try that on V1 since I'm using red bases which are relatively short. Any suggestions on this idea?
     

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