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Valve Dampeners


mikey d
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Isolation of the amp itself has more effect.

 

And given that a valve amp generally proudly displays its valves in the open air, outside the case ... how the hell does one "isolate the amp" (ie. isolate the valves) from air-borne vibrations? :P

 

Regards,

 

Andy

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Well............given that it is a 'vacuum tube',,,,,,,,,,,,,,what vibrations are we talking about!

: )

Aah, OK ... you haven't heard of valves being "microphonic", it seems.  You need to eddykate yourself, mate. :P

 

 

Regards,

 

Andy

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Some of the "damaging vibration" is transferred through the floor as well as air (probably even more important unless you are keeping the amp infront of a subwoofer). So, amp isolation pays off.

 

Either way - it is probably the most effective to find less microphonic valves than spend money on esoteric dampers. There are some very effective dampers that do not cost a lot of money and some DIY versions of those. Maybe worth wile exploring...

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An example of microphonic valves is the standard Russian 6N1p, the issue is neither from lack of isolation and neither a result of airborne vibration. Although these things could/will compound the issue. The other two varieties are less prone, the "EV" variety being the least problematic.

 

The issue is where the internals are braced against the glass envelope, microphonics are a result of the mechanical vibration between these points. This is why when placing damping rings on the valve, you position them where these points contact.

 

Some valves are better than others in regard to mechanical vibration.

 

I think that makes sense :confused: this is how I understand it anyway :cool:

 

Edit:Typo

Edited by datafone
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If you do decide to get some, don't get ripped off with the HIFI ones. Get in touch with an "O" Ring supplier like International Seals at Mona Vale and get the red hi temp ones to the size of your tubes. Couple of dollar for the big output tube ones and less for the input tube ones. (don't get them too tight as they will over time dent the glass)

You don't need them if your tubes are not microphonic, the way you can test for this on power amps, is to flick with your finger nail each and every tube on the top with the amp on while someone listens at the speaker for the noise if they are microphonic they will make a "gonk" noise. For preamps you need the volume up to hear the input and phono tubes.             

Edited by georgehifi
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There are a horde of O ring suppliers in Sydney.

What area are you in?

In the bush bro. I guess a local engineering shop would have some O-rings. I am familiar with the heat resistant red ones. I had them on some ECL86 output valves on an amp once & found that they perished rather quickly.

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Thanks for your input guys. I don't have any microphonic problems with my 12ZX7's in the pre stage. I was really wondering if they added any mechanical stability to the valves.

 

Gluing them in with silicon would add stability and help with dampening.

Makes it bloody hard to change them though!

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In the bush bro. I guess a local engineering shop would have some O-rings. I am familiar with the heat resistant red ones. I had them on some ECL86 output valves on an amp once & found that they perished rather quickly.

 

Yeah.........if they sell bearings, they will have O rings.

Ask for silicon or Viton ones.

Edited by LogicprObe
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This is what Steve Herbelin of Herbie's Audio Lab told me......

 

"All tubes are prone to microphonic and microvibational distortions to some degree or another. Different tubes and components will be more susceptible, some less so. Direct heated triodes like 300B are very sensitive to vibration and usually audibly noisy. However, none are necessarily more susceptible than others, so there's no one-size-fits-all rule about which specific tubes would be more significant than others to damp. Ideally, you'll damp each tube to bring out the most inherent potential of your gear. Small-signal (preamp) tubes, rectifier tubes and power output tubes are equally important to the audio result. If starting out with limited damping however, it usually makes sense to start at the source and then work your way along the signal path, or prioritize (phonostage first instead of preamp, for example). It's equally important, of course, to isolate/decouple each component as a whole as well, and so you might consider four Tenderfoot isolation feet for each of the components."

 

hope  this helps........

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Andyr

Your general vindictiveness towards all valve technology is renowned

If people want to decorate theirs with colored plastic rings let them be

You probably don't have a Christmas tree as they remind you of glowing valves

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