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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

Showing 2 responses by atmasphere

atmasphere's avatar
atmasphere
12,105 posts
 
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.
atmasphere's avatar
atmasphere
12,105 posts
 
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.
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