Where to place tube dampers on preamp tubes?


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dpac996
The CJ DV2B CD player I have came with two dampers per tube placed at about the third way points on the upper and lower parts of the tubes. Hope this helps.
I always thought you placed them where the mica supports are.
There are the silicon rubber tube dampers that probably best brace a tube at least in 2 locations corresponding to the micas. My question is do you really need them? I have played with them on my preamp tubes but haven't noticed a difference. They look cool but not nearly as jewel like as Andy's Vacuum Tube services dampers but these are brass jackets inner silicone rings and are gold plated just for looks. See Positive-feedback this month.
I find they work best at the top. Put them as high as possible to act like a transmission line termination. Soak up all frequencies, not just fractional harmonics of your 1/3rd spacing. I'm guessing this is how the "top hat" idea came into play. Placing them over the micas will also work, as that would be the entrance point for vibration.

I use hi-temp o-rings, but they are hard to put at the top, one roll and they end up about 1/3rd down. They're not the best solution, just cheap.

It also helps to damp the socket itself. Usually they are made from several pieces and held together somewhat loosely by a rivet or crimps. What worked for me (at least with PC-mount style) was to drill out the center rivet and bolt the socket down to the circuit board. Damping the chassis and circuit board with cork or foam or rubber or similar can also go a long way. No point putting o-rings on a tube if the socket itself is vibrating.

jh
Dave, I use Herbies Hal-O damping instruments(rings) in the LS-15 with EH6922 tubes and have them as close to the top of the tube as possible. i tried them towards the middle of the tube and at the base of the tube. Found the preamp sounds best with these things at the very top. I guess this way you kind of get the best of it, because you don't overdampen and by that you are not killing the sound of the tubes. If you have highly microphonic tubes, which you don't, then putting the dampers at the base or in the middle of the tube would be better.
But basically, it all drills down to preference. It's worth to experiment. Although with the stock ARC tubes rings it may not be that easy, I don't know. Herbie's just roll on and off the tube, so it was pretty cool to experiment. Just don't forget to turn the pre off.....
I agree with Audphile 1.
http://herbiesaudiolab.home.att.net/

As far as the black damping ring supplied by ARC, this is what ARC says,

"The single black damping ring should be level and located 1 1/8" (1.25" or 2.8 cm) above the bottom of the glass portion of the tube as measured from pin end of the tube to the center of the ring".

"Take care when installing each tube in its socket so that you don't push the damping ring from its proper position".
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If you accept that no tube damper eliminates resonance, then like almost all other hifi tweaks, you're just putting a "fixed tone control" in your system, and maybe a transient clarifier. Hence a further variable is the placement of the damper on the tube. Also the tension of the damper. Its mass, etc., etc.

If you're going to use these things to tune the sound of your system, you might be reducing elements that obscure information, but more likely you are making a compensatory adjustment for some other trait in the component or elsewhere. Therefore, just work the remaining variables and keep it up until it's better than it was before or your patience or interest run out.

Phil
06-15-06: 213cobra
If you accept that no tube damper eliminates resonance, then like almost all other hifi tweaks, you're just putting a "fixed tone control" in your system, and maybe a transient clarifier. Hence a further variable is the placement of the damper on the tube. Also the tension of the damper. Its mass, etc., etc.

If you're going to use these things to tune the sound of your system, you might be reducing elements that obscure information, but more likely you are making a compensatory adjustment for some other trait in the component or elsewhere. Therefore, just work the remaining variables and keep it up until it's better than it was before or your patience or interest run out.

Phil
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So what are you trying to say? Do you have tube gear? Do use use tube dampers on at least the driver tubes?
In your posts you mention alot about tube equipment.
Do you consider hi-quality caps and resistors as tweaks? They will effect the sonics of an audio system.
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Jea48,

Yes, I have tube gear. All my systems have had tubes in the amplification chain for over 30 years. Currently I run 2 tube systems. Preamps include Klimo Merlino Gold, Audion Premier 1.0 and a vintage Stax SRA3. Power amps include Audion Black Shadow 845 SET monoblocks, Audion Golden Dream 300B PSET monoblocks, Audiopax 88 monoblocks.

I do not use tube dampers at all. They do affect sound but do not necessarily make it better, just different in easily tunable ways. And they make my systems less consistent day-to-day. I actually have found tube dampers to increase, rather than decrease, airborne effects. Point is, there is no one correct place on a tube to place a tube damper if you're going to use them. Some resonance will be left, so sound will change according to placement, material, tension, etc.

"High quality" caps and resistors are tweaks, yes. That is to say, these changes can be heard but the new sound is not always -- even often not -- better across the board. What's quality? Metal film resistors don't always sound better. They often sound worse. Is a Hovland cap better than Black Gate or vice-versa, sonically? It depends. There are designers that hand-roll their own capacitors because nothing manufactured sounds correct to them, yet the quality of their hand-made caps would be judged as lower, by most professionals qualified to judge on parts domain expertise alone. What about silver wire vs. copper? Then you get to the insulation -- cotton, Teflon, vinyl or synthetic fiber? Oh, then there's solder. Or forget solder, how about all joints crimped? Uh, then what metals are the crimped connections? It goes on and on, yet no one can tell you in advance what combination of materials, techniques, design and parts will get you closest to the musical truth. Most tweaks make you give up something to get more of something else.

I've modified and built from scratch many tube amps over the years. You learn some general patterns for improvement, but a lot of upgrade options that people are herded towards are quite circuit-dependent in their effects. Also, often audiophiles are tweaking gear to compensate for problems elsewhere in the system, and when the tweaked piece is moved into another system, the upgrades may not have the same value.

So what am I trying to say? That if you can't feel settled about what you have and you're not inclined to replace whole pieces of gear, then realize that tweaks are a bit like "fixed parametric equalizers." If you're lucky, some will actually strip away layers of obscuring haze, but most will simply alter the balance of your system and a lot of tweaking ends when you perceive you've achieved a pleasing and subjective balance of factors in your system, rather than having arrived at an objective improvement, or something more "correct." There isn't one right way with tweaks.

By the way, it's the same thing with most cables, too. All of this is one of the things that make audio interesting, and yet it's a very fine line separating interesting from compulsive and distracting.

Phil
After many years using many tube dampeners, I would have to agree generally with 213cobra. Presently I have Herbie high temperature rings on my 211 tubes and Top Hat (basically lead with a center hole that sit on top miniature tubes. I have often found that tube dampeners on miniatures rob the music of pace and clarity. There is nothing better than a miniature that is not microphonic. I had a preamp that used the WE 417 tube, most of which were microphonic and none were helped by tube dampeners.

Certainly I have never seen so exact instructions as those coming from ARC, but maybe they are right.
Well said, Phil.