Expanding questions about tubes in a preamp

Hi,
i would suggest to experiment with Herbies tube dampers, check them as there is variety of those, and not loose their grip or pressure on the glass over time. Silicon or rubber ones do work somehow are cheap but get loose or crack after some use due to heat. Whatever you choose will do in vibration control tame microphonis and make your tubes sound more linear if you want that. What i have found is that putting them on the upper part of the envelope, above top mica, is less affecting the tube character.

Uh, they’re all microphonic, even the ones that say ultra low microphonics. I used to get all my 12AX7s and other tubes from an insider who worked in maintenance at Goddard Space Flight Center, they were all WA military grade tubes. Sylvania, RCA, mostly. The only tube dampers that actually work and don’t hurt the sound are Herbies tube dampers. The rest of them you can throw in the trash. On 6SN7 tubes you should realize even better performance by using two, two dampers, one on the glass where the getter is located and another on the tube base. Yes, I know what you’re thinking, “but then I’d be spending more for dampers than I did for the tubes!”

Herbies tube rings are the only way to go the others over damp the tube and you loose life and dynamics.

if you buy into the tube damping thing, may as well go big
https://shop.mapleshadestore.com/Standard-Tube-Halo_p_1268.html

I use quiet  tubes, and I'm done with it. Careful, the more you learn, the more it increases unnecessary obsession. 

Getting rid of microphonic tubes is far more important than damping rings. They have a tiny effect by comparison. I would only use them if you already have decent tubes.

Heat in tubes causes failure. The more damping rings and the like, the shorter the life.