Tube rings for power tubes?

I would suggest going to herbies
herbiesaudio.com
and asking Steve Herbelin what he thinks. I know him to be honest in every trans I've had with him.
His line level dampers are tremendous.
IMHO

They CAME with tube rings? Are they the rubber (tube damper) type or the metal (heat radiating) kind? Where did you buy them? Did you ask the seller?

OK, I haven't heard of this or seen it -- ever. First, power tubes get so hot they'd burn/melt most tube rings, even the ones made with special silicon rubber. Two, good power tubes are not generally susceptible to microphonics like preamp tubes are, so damping is not really necessary.

The heat dissipating types (with metal fins) are not really any more effective than just leaving the glass exposed -- and could cause hot spots on the glass.
.

NSgarch- I'm a little reluctant to contradict you, since your posts are always thoughtful and (to me, anyways) very informative, but... I have some Herbie's on the 300b power tubes in my Cary 300 SEI. Now I don't push that amp very hard but there is no evidence of any discoloration anywhere, and I just checked the portion of the damper that actually touches the tubes. Maybe on a KT-88/6550 push/pull amp, but so far they are OK on my 300b amp.

FWIW, I use the herbie's tube dampers on the KT88's in my Cary SLI-80 with no problems. Herbie sells a version specifically for high-heat output tubes.

Another vote for Herbie, his rings are very reasonably priced and graded for tube heat. I have had no problems on my 845's and what gets hotter? I am sure someone will tell me.