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
Hi,
looks silly or not if it works it's ok. If my memory is correct ARC did supply tube rings sometime with their gear. Virtually all tubes have the tendency to be microphonic (more the signal tubes) but it does not mean that they are bad ones. Most depends in their location on the circuit, a gain stage will expose it more and a driver stage less, so sometimes you do not even know it. Have you tested that all the tubes you are using are not microphonic and how? What sound do they make when you tap them?
Everything works, and my comment on a previous post that they sound more linear after using a tube damper is because microphonics/micro vibrations are somehow reduced. Last about hissing, we are talking about tubes which obviously have more hiss than ss.
A  with tube damper testing is it is impossible to install / adjust them without moving the tube and refreshing contacts.

Dampers could work by two methods: Vibration control and resonance damping. Assuming the envelope vibrates, what happens? The tube is a vacuum and sound does not travel in a vacuum. It could damp sound, which has very little energy, from travelling down the envelope to the base and up into the electrodes. One should be able to mathematically calculate the energy required to vibrate the electrodes. If resonance damping is the m.o. then where the damper is placed will affect its utility. Since all tubes vary slightly, how does one know if the location is correct for the particular tube. Model or item. AT, AU,  AX, AY, BH // 66, 77, 88, 90, 120 150 for but two families.

It is quite trivial to set up a test wherein one records the output of a tube device w/wo dampers and delta the difference.

Since damper claims are anecdotal, I assume it's never been proven.
ieales

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ieales
A with tube damper testing is it is impossible to install / adjust them without moving the tube and refreshing contacts.

Dampers could work by two methods: Vibration control and resonance damping. Assuming the envelope vibrates, what happens? The tube is a vacuum and sound does not travel in a vacuum. It could damp sound, which has very little energy, from travelling down the envelope to the base and up into the electrodes. One should be able to mathematically calculate the energy required to vibrate the electrodes. If resonance damping is the m.o. then where the damper is placed will affect its utility. Since all tubes vary slightly, how does one know if the location is correct for the particular tube. Model or item. AT, AU, AX, AY, BH // 66, 77, 88, 90, 120 150 for but two families.

It is quite trivial to set up a test wherein one records the output of a tube device w/wo dampers and delta the difference.

Since damper claims are anecdotal, I assume it’s never been proven.

>>>>>You sure make a lot of assumptions. When you ASSUME something you make a fool out of me and UMA Thurman.
I've actually tried dampers and they provided zero improvement of the tonal aspects of any part of the performance of the tube amp and preamp, not unlike Kaitty's futile and irrelevant snarky posts. Microphonic tube paranoia is simply providing another tweak people can hang their hats on that has zero basis in sonic reality...if a tube seems microphonic, don't use it. Problem solved.