Tube Dampeners...

Discussion in 'Amps and Cabs' started by Lemuel.Tan, Feb 5, 2008.


  1. Lemuel.Tan

    Lemuel.Tan Member

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    Came across these on eBay just today, they look like really thick rubber bands strapped around the tubes. Said to greatly reduce the microphonics of tubes due to vibrations. Will make good tubes sound great and the microphonic and inexpensive ones sounding much better than they normally would. Has anyone ever had experience with them? Care to share if they really help or are necessary?

    Thanks!
     
  2. hardys

    hardys Member

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    TIP: You can get high temperature silicon caulk/sealant at the auto parts store and put it on preamp & power tubes and get the same effect. Heat shrink can also be used.
     
  3. justonwo

    justonwo Supporting Member

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  4. Lemuel.Tan

    Lemuel.Tan Member

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    Thanks for the tip! Any particular brand or what to look out for? And more importantly, do they really help to improve tone?
     
  5. rockon1

    rockon1 Member

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    They will help reduce microphonics, nothing more. And like hardys stated you can use virtually any fairly high temp o ring-whether you find them at Home depot or Auto Zone.... If the tube isnt too microphonic to normally use they are not helpful or necessary. Bob
     
  6. Lemuel.Tan

    Lemuel.Tan Member

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    Thanks! May try out on just a tube or two (of the more microphonic ones that I have) to hear for myself.
     
  7. hardys

    hardys Member

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    Mesa used to (don't no if they still do) sell what they claimed to be super low noise 12AX7s. The were Sovteks with heat shrink on them. They claimed they tested them for low noise as well. About $20.00 a pop 6 years ago!:rotflmao

    I've also seen Dr. Z amps from the factory with heat shrink on EF86s tubes. Those tubes can get microphonic easily.
     
  8. frank4001

    frank4001 Member

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    They worked for an EF86 I had in a combo...I paid allot for the tube and my understaning is even the best ones tend to get microphonic....Well these tube things saved me allot of grief...Good Luck.
     
  9. rockon1

    rockon1 Member

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    Its important to note that most tubes that are too microphonic to use in the V1(the most sensitive position) can be used in the remaining spots as they are less susceptible to microphonic tubes. Bob
     
  10. Lemuel.Tan

    Lemuel.Tan Member

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    Right on Bob. So anyone else has had luck with these dampers?
     
  11. Groovey Records

    Groovey Records Member

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    I have been having trouble with microphonic EF86 tubes. EH, Winged C, NOS Dario Mini Watts. I have ordered some NOS Mullard longplates and a highly recomended NOS RFT EF 86 (tesla) pretested for lowest microphonics.

    The EF 86 was originally used as an analog microphone tube for some of the best studio mike available in the fifties and early sixties. Vox used them in their early AC15 circuits for THAT special sound.

    It is highly debated whether dampening guitar tubes tames the sound or effect which we seek? Some swear by dampening others say it dulls the sound.

    The EF86 is the most pronounced culpret in this field and finding the right stable tube takes time.

    If these new pretested NOS tubes still allow that clinking glass noise behind the sustained notes and chords I play I will try dampening.

    It is important that you do this before the tubes rattles and turns Microphonic as a prevention not as a cure

    These Halo Dampeners are highly recomended by a friend of mine who knows and loves this circuit and these tubes.

    Here is what he had to say

    In regard to the EF86 and dampening rings, they are such sensitive tubes that you can look at it both ways and it's argued both ways all the time. They are so unstable that a dampening ring is thought necessary and a plus by some , but they are so touch sensitive that it's argued by others that they change the sound and performance of the tube for the worse. It's all a matter of preference. I say use your ears and decide for yourself. I switched to those RFT EF86s, I love them and use no ring on them but if I were to, I'd use a HALO: http://herbiesaudiolab.home.att.net/halo.htm

    [​IMG]

    I think this is good advice

    Best
    Groovey Records
     
  12. mcdes

    mcdes Member of no importance

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    the halo looks interesting?

    i tried dampeners couple of weeks ago on my ef86 channel and top boost channel.

    i found in both instances, that it dulled the amp and it lost its clarity, didnt like it at all so they came out pretty quick, but try for yourself.
     
  13. mcgriff420

    mcgriff420 Member

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    George alessandro just sent me a new SL7 with the dampning material installed. When the SL7 is in the first spot and there's a 12au7 next to it it's always microphonic so the ring definitely helps in my situation. Since it's not removable and it's a different tube than the one it replaced I can't say if it dulled the sound or not. But my Redbone is still really responsive and anything but dull!

    ..
     
  14. Blue Strat

    Blue Strat Member

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    Dr Z told me that he does this more to keep the tube from rattling against the wire tube clamp for the EF86, or vice versa.
     
  15. mad dog

    mad dog Silver Supporting Member

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    don't know what to think about these. Just put them on all tubes in a Sewell, at the gig V1 (a great old RCA 12ax7) started feeding back. I put them on to forestall microphonics, instead got it immediately on my favorite tube. Just a nasty coincidence???
     
  16. jay42

    jay42 Member

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    You can try o-rings, provided that they are Viton or Silicone. The average o-ring is a 250F part. These other formulations are good to 400F. Easy enough to google. http://www.orings.com/product_standard.asp
     
  17. hasserl

    hasserl Member

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    Guys, think about the physics involved here. You have a tube that vibrates due to movement of a speaker. The vibrations travel thru the cabinet to the chassis (in a head/cab there may be rubber feet between the two cabs to dampen some vibration), to the tube. Wrapping a piece of rubber or anything else around the tube is not going to change the rate of vibration of the tube. It simply can't. Unless it also changes the weight of the tube, then it is the added weight to the tube that changes the frequency at which it vibrates, the more weight added the more the damping effect. A piece of heat shrink tubing shrunk around the glass envelope won't add much weight, and won't make much of a difference in sound. An o-ring might help a little, two of them may be better than one. Those halo devices, the definition of exotic materials may sound nice, but IMO it's mostly just marketing. All you need is something that fits snugly around the tube that won't slip off, will resist the heat (preamp tubes don't get too hot), and will add some weight to the tube to shift the resonant frequency. You don't need exotic materials, they won't effect the sound.

    Something else to consider, if the chassis is vibrating at one speed, and the tube is vibrating at a slower speed with less amplitude, there has to be a point where this difference in speed and amplitude takes effect. Where might this point be? It's got to be at the pins/socket. Think about it, if you could magically apply something to the tube that would keep it from vibrating at all, making it remain motionless, while the chassis was vibrating away at full force, don't you think there would be tremendous stress and wear at the pins and socket? Meaning the dampeners might help reduce noise in the tube, but eventually they will cause wear at the pins and socket leading to a loose fit. It's a trade off IMO. Use the least amount of weight it takes to dampen the vibes with the least amount of wear to the pins and socket. OR use more weight to dampen the tubes accepting that it will cause a faster wear rate at the pins and socket.

    edit: fwiw I've had good luck using rubber grommets (made for protecting wires passing thru a metal chassis), the ID of which is a match for the OD of the tube, then wrapping a piece of solid (not flux core or rosin core) solder around the grommet to fit in the groove. It provides a snug fit and adds more weight than an Oring. The grommets seem to withstand the heat from the tube just fine.
     
  18. Echoes

    Echoes Senior Member

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    tube dampeners are like those garter belts old guys use to hold up their socks... :D
     

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