Do tube dampers really work?

Tube dampers are relatively cheap; but will they REALLY improve the sound of my Audible Illusions preamp?
I'm using Mapleshade tube anchors on both my SuperIT phono stage and my CJ Premier 14 line stage. They're a pain in the neck to install but they REALLY improved the sound of my system.
Having just been told in no uncertain terms by several other Audiogoners (in another recent thread) that tube microphonics have been a non-issue since the 1940's, I hardly dare to raise my head here. But I can't resist. Lessee, you've a bunch of hairthin wire wrapped round and round some rather flimsy posts sticking up into free space, all wrapped up in a glass bottle. And this whole thing is guaranteed to be absolutely 100% impervious to vibration of any kind (not 99.9%, but 100%, mind you!). I ain't buying it, even if it's free.

If you really want to know for certain, take the cover off your tube preamp, turn on your system, turn the volume up, and twack the tubes nice and hard with your fingernail. Do you hear anything through your speakers? That will be pretty indicative of whether tube dampers will help or not. Disclaimer: DON'T TOUCH THE ELECTRICS inside the preamp!

If you try it, let us know what you find.
Most definitely yes, but it does take some experimentation
to find the best items for a given system.
A friend of mine, who is a tube seller in Germany, test the Herbie's tube dampers in his own designed microphonic tester. He recorded a max of 6dB of microphonic level being reduced on a E88CC tube with the Herbie dampers.
Yes but you also have to add a weight to the top of the tube. There were a few companies selling these a few years back but you can make your own by going to the arts and craft store and buying some lead ribbon and making a little circle to fit on top of your tubes. Cheap and effective.
Smacking the tubes while running is not an effective test of microphonics. Just a stupid thing to do.

I'm using a set of 6 Hal-O tube dampers from Herbie's Audio Lab (on both preamp and amp). The cost was $95 with a 90 day money back guarantee. There's no way mine are going back. The change in my system was dramatic.
If you remember I was posting about microphonics in tubes since I had them in freequent practice for quite a-bit working with powerfull UHF radio transmitter.

Tapping tubes is NOT a microphonic test since it exceeds air pressure gazillion times. I urge NOT to do that test.

What you can do is tap on chassis or interconnect wires and if you hear clicks-pops than you have a case with bad tube you need to examine.

As to dampers they eliminate vibrations of "bottle" but found tube coolers at can prolong a tube life. Still not sure how it affects sonics since it's simply to say a teaspoon in the ocean to the different components speakers room, temperature and even air content.
Like chicken soup for a cold: it can't hoit!
Yes, I know that tapping tubes is a much more severe G load than typical air loads can impart. However, it is significantly closer in magnitude to conceivable chassis-borne vibrations. (Have you ever put your hand on your preamp's chassis while loud music is playing?) Still higher, I grant you, but this is really a matter of simple physics. In fact, one of the simplest of all physical equations. Namely, that a specific force will cause an acceleration (and yes, a subsequent ringing) that is exactly proportional to the magnitude of that force. Moreover, a simple fingernail tap is about as close to a step function as you can get in a no-cost test, which has all kinds of benefits in analyzing how a tube (or any other physical/electrical system) reacts to transient perturbations (which is about as close to a general definition of a musical signal as you can get). So yes, the test I proposed is more severe than the tubes are going to see in normal service, but it is nevertheless a totally valid way of easily demonstrating that tubes are indeed sensitive to vibration. Anyone who denies this as an absolute impossibility has their head in the sand. (And I'm being polite here.) Go reread Hee's post above and then tell me that this problem doesn't exist.
The Hal-O tube dampers work good for me. It's a sultle improvement but worth doing! One thing I have noticed is you can fine tune your system some what by moving them up or down the tube, I have the Hal-O about 1/3 down from the top as this gives me the most improvement. Happy Listening!
I don't know what the theory is but I have 8 Hal-O in my BAT VK-50SE and they really work wonders.

What was the reading with the same tubes prior to fitting them with the Halo dampers? That would make this a meaningful comparison..
Another vote for Hal-o tube dampers. They worked for me in my preamp. Cheap too.
Like others above, I also use the Herbie Hal-Os in my pre-amp-- very nice improvement, and like Jswhitlock, I found the Hal-Os able to change the sound as they were moved up or down the tube. Mine worked best about 1/2 way down. Cheers. Craig.
I am also in the Herbie continuim...nice little tweaks, bout' half way down as well..
Owned a audible illusions ,made an improvement
I am using Shun Mook Valve Resonators, which are more than tube dampers, on the input and output tubes. I could not believe they work pretty well on my system (Berning amp) with more musical, lively and lush but detail... The Valve Resonators can adjust the sound you want. I will try them on my preamp later. Good luck.

I couldn't tell the readings before and after using the Hal-Os. You may want to contact my friend (in Germany) if you're really interesed. He could be reach at

FYI he's a honest tube seller and he has to measure tubes, to grade the good tubes and to scrap those bad tubes. He measures tube parameters and microphonic. So I sent him 2 sets for measurement of microphonic reduction.
When tube is microphonic it's definitely bad. Dampers help to run that bad tube with more time "unaudiable". Try to compare readings on half-dead tubes using Hal-o dampers.
I was curious about what sound people were hearing as they were moving their Hal-O tube dampers up and down. There seems to be a classic tradeoff of: thinner bass, more detail, vs. tubbier bass, warmer midrange, less detail. Is that what you've heard when moving the dampers up and down, or something different?

I am curious about what people notice, too. What are people hearing as an improvement?

I understand how less vibration would help with sound and that heat dissipation might prolong the life of a tube. I really like any idea that is cheaper and works. Bigkidz offers the lead ribbon idea. That would get the weight but would not lead concentrate the heat in one spot?

I have seen the Hal-O things listed here a lot. Andy from Vintage Tube Services is highly respected and he offers gold-plated brass dampers. BUT, they are to the tune of FIFTY-FOUR dollars EACH for small tubes like the 6922. Has anyone tried these and are they better in relation to the price difference?

Tubes are microphonic in nature, try knocking anywhere near the tube socket.

Up /down, lose/tight - the magnitude of damping.


Can a metallic clamp added on a tuning fork prevent the tuning fork from vibrating when being stroke? A metal clamp will only change the resonance frequency.
If you want to know what HAL-O's do to the sound, check out their website. Many people describe what it does for their systems under the review section. You can find the website through the manufacturers list on Audiogon.

They have made a big difference in my system, particularly in 3D spacial characteristics.
I recently bought the new Pearl Tube dampers. I didn't notice any difference in the musical presentation, but what I did notice is the elimination of some minor microphonics of my NOS Telefunken E88CC's. Also, they significantly reduced the temperature of the tubes and this is a good thing - the tubes will last longer.
I have used the ARC rings with good results and as a result of this thread ordered the Hal-o rings from Herbie's, not to be confused with Herpes :)

These rings improve performance in several areas but might vary with the components they are used with. First there is a notable lack of microphonics in my new Supratek preamp which I recently received and which was a bit noisy at times, especially with those confounded but wonderful Ken Rad 6SN7 line tubes. The other area is clarity and image focus which I also noted with the ARC rings. They are well worth the expense and to answer your question, yes, they do work. As with all such things, YMMV. For the cost I would give them a try since there is no obligation if they don't. A cheap tweak worth the expense.
Hi Folks...

I'm from Israel, owning a ARC-SP-9/2 + a Dynaco Stereo 70 also series 2.

Thanks to a friend of mine that works for the Army, here..., I obtain from him a lot of "O" rings, widely used for many porpouses in the army, and loaded my Pre + amp with a lot of these "O" rings.

IF...?, I really hear a Improvement....Maybe I'm dreaming!

BUT... make me feel much better!

In those 2 Amperex white PQ 6922 that I installed in my SP-9/2 they obtain 3 "O" rings each one of the tubes.

My Dynaco the two drivers 6GH8A also 3 "O" rings each tube,
for the 4 National branded East Germany Siemens, as was received 16 "O" rings in total > 4 "O" rings each tube.

Of here in Israel it's an a very hot zone..., my Dynaco always work with NO grille,,, the SP-9/2 With!

Good listening...

There seems to be some agreement that tube dampers offer an improvement. Why would a manufacturer of a relatively expensive preamp (over 4K) not offer a tube damper as part of the standard equipment to "improve" performance, or at least offer them as an uprgrade? They are not generally very expensive, especially purchased in quantity. If ARC can do it...
Well, ARC does it on all their stuff, one of the reasons I like them. As for why others don't, the cynic in me wants to say that they probably don't want to admit that it's a problem. There's a psychological issue with admitting to yourself that tubes are sensitive to vibration, makes them seem somehow less "perfect" than they were before, and also makes the customers start asking difficult questions, like "why aren't you doing more to isolate the tubes from vibrations, if vibrations clearly cause a performance degradation?" Best not to go there. Witness the several responses above stating categorically that microphony cannot possibly exist unless the tubes are obviously defective. To some, a problem ignored ceases to be a problem. I just wish it worked for me:).
I just fitted the input 12AT7's on my VTL mono's with Herbie's Hal-O dampers. At first I was skeptical, because in a preliminary 'unplugged' test where I just tapped the tubes when pinched lightly at the pins and tip between my thumb and forefinger and listened to the airborne ring of the glass envelope, the dampers really only seemed to slightly modify the pitch and duration (as Hee suggested above), but they still rang nonetheless. Not only that, but the actual damping pads are quite bouncy when dropped onto a hard surface, which to me is more the characteristic of a spring than of a damper.

However, when I compare with the Hal-O's both on and off the tubes installed in the amps playing music, there is a (mostly) worthwhile difference to be heard through the speakers. Specifically, the dampers can help in taming brightness that is likely spurious, the result of resonances. I suspect that the Hal-O's can't help much with tubes which are themselves significantly microphonic. The benefit I heard was with tubes displaying no audible microphonics at normal volumes through the speakers (not headphones) during the tap test. (BTW, the tap test is perfectly legit - it successfully identifies microphonic tubes. What else does anyone need from a microphonics test?) I admit I was kind of suprised to hear much of anything at all with tubes that didn't seem to have any obvious problems beforehand. Just goes to show how critically sensitive all input tubes are.

A potential bit of downside can be a minor loss of 'air' - which could also be a spurious artifact itself - along with a slight diminishment of perceived 'snap' or 'jump'. On balance, in my system, the tonal balance correction is more significant. I don't want to get carried away though - the total effect is small, but consistent and to my overall liking.

I doubt there's anything special about the Herbie's dampers' sound in relation to the all-silicon ring-type dampers ; in fact, the Hal-O design, which creates an added partially-damped suspended mass to resonate, in the form of the Teflon 3/4 ring, might not be as ideal as something that contacts the glass all around and is lighter in weight. But the Hal-O's seemed like an appealing design as far as being easy to install and remove even when the tube is hot, are just as cheap, and they can look kind of cool. Since I haven't yet tried any but the Hal-O's, this is just speculation for now.

I've also got no experience with dampers that take the opposite approach and go for high mass, usually through the liberal deployment of brass. To me, these seem like they would unavoidably retain more heat, wearing the tubes out faster, and given what they cost, I don't know if I'll ever try any out. The Ensemble Tubesox look interesting - and like they might give the best damping of anything - but are also expensive. Again, it seems to me they must somewhat increase heat retention - something the Herbie's design avoids completely. I've used the Pearl tube coolers on several tube types, both output and small-signal, for a number of years, and though I think they perform well in their intended job, I can't say they do much to quell microphonics, and can even ring a bit themselves. (It also seems as if they would provide a more efficient means of picking up airborne vibrations ; in the VTL's, I use them on the hotter-running driver tubes, but not on the more vibration-critical inputs.)
The ARC LS 25 I bought used last fall came with Amperex NOS tubes and Hal-O-Dampers. Only thing I can say: the dampers do look cool. Do they affect the sound? As you have all realised: I'm too deaf to know! One thing I can say about dampers is that the stock ones from ARC I also got with the line stage were installed in the PH 3 phono stage. Result? Damn I can't hear any difference! So I must be deaf, or else I simply lack that extra bit of imagination a true high-ender can't live without. Good day.
On well designed tube equipment whether you knock or don't on tube sockets(in my case I can even knock on power tubes) it will have no microphony effect whatsoever. Whenever I spot some microphony from any of my tube components It's time to replace tube(s). The tube components I have is VTL MB100 monos and ARC PH3.
Pbb, in your case you're dealing with well-designed component that won't be affected with any tube dampers or any other such tweaks.
Marakanetz: I don't agree that subjectively dubbing a tube component "well-designed" has much to do with whether or not you'll find any symptoms arising from resonance problems which are inherent within the tubes, not the amps. Some evidence of this might be noted in the fact that ARC itself installs tube dampers on the gain tubes in their amps. It's true that amp chassis and PCB's can be designed with higher or lower rigidity, and internal suspension and damping measures may or may not be taken, but those last two can also be effected externally as tweaks, and whether the first factor winds up aggravating tube resonances or not is probably as much a result of chance as of design. Regardless, tube microphony will in theory always have some deleterious effects on the music (even with tubes passing the tap test), which no amount of component engineering or heroic construction can eliminate, so I think experimenting with tube damping is never inappropriate.

Pbb: I can't guarantee anything of course, but I'll tell you that what pushed it over the edge for me, as far as confirming results goes, was listening to prominently-mixed, well-recorded vocals in a sparse instrumental setting. (Solo piano is good too - live piano usually sounds mellower than most recordings played through most systems.) With the tube dampers installed, vocals sounded more like voices coming to me only through air ; without the dampers, they sounded more obviously like microphones were interposed. Since microphones *are* of course in between us and the singers, the presentation which is more 'correct' must be a judgement open to debate, but at least with my amps in my system, I am finding the sound more natural with the dampers fitted, and suspect the 'microphonic' quality I'm taming literally originates with the tubes. Anyway, the differences I'm hearing (again, with my amps and system) ain't huge, only subtle, but they are pervasive and perceivable, and I would suggest you try again sometime to listen for 'em...