Tube Dampers and Heatshrink Tubing

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Russ

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What are your honest thoughts on these wrapped around preamp tubes?

Would these help older tubes also? Could it help a tube that is going microphonic already?

Why are so many people going this route?

I have now seen more than a few manufacturers/ distributors with them on their tubes. I have also seen variations of the styles of them from simple o-rings to industrial grade heatshrink. Some of tubes I have seen them on are Mesa, JJ, Sovtek, EH, Randall (in their modules), NOS offerings, Ei, EH, and Chinese.

I would think that the heatshrink would put undue stress upon the outside of the glass that is already pulling a vacuum from the inside. I would also think that the o-rings would eventually sag off from heat degradation.

Also wouldn't any material on the outside of the glass retain more heat thus reduce the life of the tube?

If wrapping your tube helps it where is the point of diminished returns where no further insulation will help but would rather impair the tube?

If your tube dampers prevent you from using your tube shields which is more important and which takes precendence? Would contact between the tube damper and shield be good or bad? Would the use of tube dampers delete the necessity to use shields?

Why all of a sudden start using such devices?

Is it hype or are there actual studies on this topic with real world valid results?

I think that they are merely a bandaid to help poorly manufactured tubes and a way to sell mediocre tubes as a more expensive variety in new production. As far as placing them on quality NOS tubes goes, I feel that it may be in an effort to disguise a shortcoming of a particular tube known to be going bad already or to try to play off of the current market hype in an attempt to make even more money off of a limited supply item.

Should we all wrap all of our tubes in dampers and heatshrink?
 
My goodness, Russ, you're full of inquisitiveness! I'm sorry to say I'm too tired to address all your questions, but here's my take:

Shrink wrap does nothing to prevent microphonics from beginning, nor from continuing. Nada! Zip!! Cheap gimmick, on cheap tubes.

There are more than several different vibration dampers on the market, and they all act on the same principle - put some mass out there towards the end of the tube, and the tip will have too much inertia to sympathetically vibrate. This does work. And don't worry, there are good, heat-resistant materials that will allow them to work under hot conditions without degrading.

But my philosopy is, don't complicate things with clever add-ons - solve the problem at the source. Just replace a microphonic tube with a non-microphonic one, and skip all the extra worries. You don't have to toss out the tube, because it may not be microphonic in another position, or in another amp.

Personally, I'd be a little concerned about adding mass to a vibrating tube that was hanging upside-down, without a retainer. Seems the tube could work loose, but ???? I haven't put it to the test. Given the choice between a tube with a damper ring, and your metal retainer, I'd go with the metal retainer.

But that's just my opinion!

- T
 

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