Tube microphonics

IMO tube dampers on power tubes will have no effect unless you’re doing it for the look. Never had a power tube be microphonic in the slightest. I’ve also never had any damper solve a microphonic tube issue in a preamp -- the solution in that case is a new tube, or a different preamp with lower gain.

Maybe. I’ve only rarely heard any tubes acting microphonics in power amps, and only for very old NOS tubes in the V1 / input slots. Amps are very far downstream in the gain structure, so microphonics are rarely an issue. Tube preamps and phono stages are a different story.

Anyways, I’ve had a few different tube power amps right besides my speakers. Never in front, but I’ve had them on bare floor, spikes, hockey pucks, isolation feet and even expensive $3K isolation shelves. Never heard that much difference from the isolation, sorry. I play loud too. Swapping the AMPS themselves, however, is always a hugely audible difference.

people posting their experience with microphonics.  The worst offender in my experience is OS (they are never really New) 6SN7.

Jerry

@carlsbad2 

Yes, I share that experience. Old GT series 6SN7 from the 1940s are notoriously microphonic. This is exacerbated by the fact that they're often shoved in high gain positions upstream (preamp), where their large plates are loosely held by tired micas and well - that's the inevitable result. However I've still had good luck with them in V1 amp slots, since they're far enough downstream at that point. That's really where I get the most benefit from my 1940s 6SN7 collection. You can still hear a little reaction if you ping 'em but not enough to worry about. 

I've not had a problem with mircophonics on the later (50s and 60s) old stock GTA and GTB series 6SN7. So if you have a problem slot and still want a vintage tube, use that. Sonically I prefer the tall bottle variants of these. 

1. Heat Dissipation: Vacuum tubes can get extremely hot during operation. An O-ring might inhibit the necessary heat dissipation, potentially leading to damage or reduced lifespan of the tube.

A ring on an audio tube is not going to be any problem for heat. Tubes are a lot better at self cooling than high power transistors. Just don't cover the majority of its surface or run them with a blanket on.