Expanding questions about tubes in a preamp

Gents, how the hell does adding damping rings change the sound of a tube. Nonsense!

Answer: by reducing microphonics. The effect is easily measured and heard.

But using a low microphonics tube is more effective yet. Installing dampers on them has the most effect.

Like most topics here, some synthesis required...

yes ALL tubes to some degree ARE microphonic. Some less so than others- certainly a classic case is the 6922 vs 6DJ8.  The key is how much and what are the modes?

The various products vary of effectiveness as broad band dampers.

microphics you can’t hear can still consume power and inject noise in a wide bandwidth system and turn into artifacts you can hear.

Start with great tubes - @bdp24 gave you good advice - Roger Modjeski ( RAM ) built some great testing and grading equipment and knew how to use it. Andy at Vintage tube also knows his way around killer but let comprehensive and automated test equipment. He can be trusted :-)

Dampers can change the sound - you may not like it. You  should experiment :-)

tomic601

...  ALL tubes to some degree ARE microphonic. Some less so than others- certainly a classic case is the 6922 vs 6DJ8. 

Huh? A 6922 is a 6DJ8. They're the same tube, just different nomenclature.

... wanted more sparkle (cymbals) and discussed doing some tube swapping to 12au7s instead of 12ax7s... May try in the future.

Have always been experimenting with isolation, and swappng out interconnects: so I went in the closet, pulled out some old Harmonic Technologies interconnects - and POP! out came the cymbals, clearer more defined voice and PrAT I hoped for...

12AU7 mu 17 and requires a lot more input than 12AX7 mu 100.
Amplifier was designed for ????
Distortion in one case will be several multiples of the the other.
Perhaps the cymbal sparkle is odd harmonic?