Tube microphonics

A thought I have *may* reduce the cost of fighting microphonics. And ChatGPT seems to agree -- to an extent:

Is there such a thing as high-temperature O-rings, and could they be put around vacuum tubes in HiFi equipment, to suppress microphonics?

ChatGPT

Yes, high-temperature O-rings exist. They're often made from materials like Viton or silicone that can withstand higher temperatures. However, their use in HiFi equipment to suppress microphonics might not be entirely straightforward.

Microphonics in vacuum tubes refers to the phenomenon where mechanical vibrations within the equipment can modulate the signals passing through the tubes and create noise or sound distortions. These can be caused by various factors such as transformer vibrations, loudspeakers, or even sound waves in the air.

Theoretically, using O-rings as a dampening material around vacuum tubes could help reduce these vibrations. However, this might not be advisable in practice for several reasons:

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.

2. Material Compatibility: While high-temperature O-rings can withstand heat, they may still degrade over time due to prolonged exposure to the high temperatures of vacuum tubes.

Therefore, while it's possible that high-temperature O-rings could help dampen microphonics, it's important to consider potential problems. There are dedicated tube dampers available on the market that are specifically designed for this purpose and may offer a more reliable solution.

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. 

Here's another tidbit of audio nervosa; never mover tube gear warm, it must be totally cooled down first. To do otherwise is to invite the tubes to become microphonic! 

Here's another tidbit of audio nervosa; never mover tube gear warm, it must be totally cooled down first. To do otherwise is to invite the tubes to become microphonic! 

and this is why i have daily deliveries of dry ice!!! 😂🤣😆😃