tube damper help

I use my own recipe. See my thread here

Brass and high temp rubber. You can find small ones at Brent Jesse "audiotubes.com". I have the something similar in a discontinued 6SN7GT size which are very effective. I don't know where you can get them now.

Magfan,
I've been using silicon "o" rings on my KT-88's for over a year have had seen nothing like you describe.They barely get hot to the touch.Maybe we're talking about different types of silicon,who knows?

McMaster.com has many O rings available, including silicone O rings with heat tolerance to 500 degrees, and in durometers of 55, 70 and 80.

If you think you need temperature tolerance to 600 degrees, they have O rings made of Kalrez® Perfluoroelastomer.

I just bought some EAT tube dampers, and still making an assessment of their effect. I do notice a difference. They make the presentation more firm and solid in the lower registers. It is probably dependent upon the type of tube you have, and how microphonic it is. I was skeptical because the 6H30 does not seem to be microphonic, but the dampers are still doing something. I was worried it would make the sound dead or soften the treble, but this is not the case. EATs won't work on wide tubes, but it is definitely worth a try.

As to claims of prolonging tube life, well who can say?