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Expanding questions about tubes in a preamp

Hello to all...

Started with a (helpful) discussion titled "How to select tubes for a line level preamp"... Expanding questions that have generated from that...

Have learned that hum/noise from tubes is a major consideration - now trying to figure cheap ways to address quieting the 12AX7s and the EF86s.

Would like to try "banding" the tubes with rubber ring washers - one?two?three per tube?

Where should the rings be on the tube: Top? Mid? Bot?

Can you over dampen a tube?

Knowledgeable tube users/ Masters input/suggestions please...

insearchofprat
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cleeds
5,964 posts
 
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.
insearchofprat OP
189 posts
 
... 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...
ieales's avatar
ieales
1,201 posts
 
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?

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audition__audio
1,502 posts
 
Dont listen to wolf he is dead wrong on this one.  
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