[Tyson]

I have dampers on all my tubes, and they do improve the focus of my system.  I'm wondering, if one hal-o per tube is good, would 2 (or 3) be even better?

[Diamond Dog]

You're scarin' me, Tyson. You're scarin' me...

D.

[Pez]

My opinion, its improbable that you could over dampen a tube, so you probably would never see negative effect from that, but at the same time I think the laws of diminishing returns would tell me 2 dampers is not twice as good as one. My guess, depending on the size of the tube you might actually get better results with two than one, but rarely would you see any improvement with three.

Also too many would adversely effect heat dissipation so don't go too crazy.

[roscoeiii]

You're scarin' me, Tyson. You're scarin' me...

D.

Says the ACer with Diamond Dogs name and DD album cover as an avatar...

[Wind Chaser]

I have had good success using Herbie's HALOs, but there have been some people who have found the best dampers are none at all - depending on the tube.  I don't believe Steve Herbelin advocates putting more than one per tube.

[ZLS]

I have dampers on all my tubes, and they do improve the focus of my system.  I'm wondering, if one hal-o per tube is good, would 2 (or 3) be even better?

    Rather than 2-3 dampers per tube, may I suggest you consider putting dampers on the capacitors. 
    I have found that it makes an audible difference, much to the better. 

[zybar]

I have dampers on all my tubes, and they do improve the focus of my system.  I'm wondering, if one hal-o per tube is good, would 2 (or 3) be even better?

I don't believe so, but lets wait to hear from Steve on this one.

George

[jtwrace]

    Rather than 2-3 dampers per tube, may I suggest you consider putting dampers on the capacitors. 
    I have found that it makes an audible difference, much to the better.

   Never heard or thought of doing this...

[emac]

    Rather than 2-3 dampers per tube, may I suggest you consider putting dampers on the capacitors. 
    I have found that it makes an audible difference, much to the better.

I agree that dampening the caps can be helpful.  Been playing around w/ Mortite (or Frost King Fingertip Rope Caulk that's readily available at Lowes) around the caps.  Doesn't always have an effect, but there's an audible difference some of the time.  So, worth a shot.

And for what it's worth, when the Mortite trick has worked, it's produced about as noticeable difference as the tube dampeners.

[Herbie]

With UltraSonic or HAL-O Damping Instruments, one damper is all you need, reducing audible microphonics efficiently enough that a second usually adds little or no audible effect. With extremely microphonic tubes and with some huge tubes like 8.5" tall 805 tubes, however, a second damping instrument can be beneficial.

Every system and component is different, however, and personal tastes vary, so sometimes a second damper is indeed preferable. That's a matter of self-experimentation, however, and not a default or mainstream recommendation.

(With less-efficient dampers like silicone o-rings, you would sometimes need two or three dampers to tame an unruly tube. But then, with each additional o-ring, you suffer from more of the sonic trade-offs incurred with o-rings and further restrict convective air flow.)

Damping capacitors is very often beneficial. Caps sometimes suffer from microphonics as much as vacuum tubes do. Dampers can be used on appropriately sized and accessible caps. I've found Permatex Blue RTV Silicone Gasket Maker (available at auto parts stores) to be excellent for damping caps, sonically neutral and extremely heat resistant.

Mortite or other brand of rope caulk is most beneficial along the interior sides and bottom of the chassis, under the lid, around circuit board mounts.

Steve
Herbie's Audio Lab

[max190]

Tyson, something you might want to try is to move the damper on your tubes.
I had my Ultrasonic 9's about 3/4 of the way down on each tube. I increased the focus and tone of my amp by moving them up to about 1/3 of the way down on the tubes.

I also recommend placing your amp on 3 to 4 Iso-Cup's w/Lampblack Ball's.

[jostber]

I have a couple of 211 tubes that can be a bit wiggly in their sockets that look like these:

f

I have one set of Hal-O III-55 dampers on these. Should they be dampened more because of the possible vibration from the sockets?

[Herbie]

HAL-O III dampers are pretty beefy and very effective. One should be all you need, though a second might be additionally beneficial because 211s are very large tubes. A second damper might not necessarily cure a wiggly socket, though.

You might pinch the pin receptacles a little with needlenose pliers to assure a firmer grip on the tube pins. The sockets themselves can be damped quite effectively with a bit of Permatex Blue RTV Silicone Gasket Maker (available at auto parts stores). Permatex Blue RTV is also excellent for damping capacitors, which can be sensitive to microphonics just as vacuum tubes are. (Rope caulk is also very good sonically and an excellent damping material but doesn't hold up to heat as well as Permatex Blue RTV does.)

Steve
Herbie's Audio Lab

[jostber]

Thanks. If you look at this article the article writer has a quite special way to solve the vibrations issue for this tube. It is specifically described in the "Dampen vibrations" papragraph.

http://ansaht.com/multi211-845_eng.htm

I guess the Hal-O damper handles the vibrations caused by the sound from speakers to the tube glass and then to the grid, but is there a way to dampen what he mentions here?


The various tests also included verifications with excursion in frequency from 50 Hz to 60 KHz; I tried different tubes, in particular VT-52, and when I used 211 / 845 tubes… worrying poltergeists started showing. The instruments revealed strange frequencies, which appeared suddenly in the most random fashion, overlapping the test frequency.
In actual fact there was a random link and it was me. By handling the measuring set I occasionally caused the tube to vibrate.
Basically, the long and fine filaments of these tubes are susceptible when they are excited by energy sufficient to cause their motion, manifesting prolonged resonances. The difference from the grid’s microphonic susceptibility is in the longer duration, as a consequence of the longer filament span.
It is impossible to forecast the level and frequency of these resonances, because they depend on the entity of the exciting force and on the small mechanical differences between the different specimens of tube, in particular on the tension of the springs supporting the filament.
The methods used to annul the effects of Alternating Current reduce its effect on the signal, but not enough, because they are not optimally tuned in.

....

In order to dispose of the energy brought to the tube through the support mechanics, we have used a technique of fractioning and reduction.
The whole structure refers to a main supporting disc (on which the glass cylinder rests), from it, through the return of three columns at 120°, we obtain a counter-plane that, through three rubber M3 vibrostops, supports the small disc for the decoupled fastening of the ceramic socket E.F.Johnson model 211.

[Herbie]

Vacuum tubes are susceptible to microphonics and distortion from micro-vibration coming from three sources: internally generated vibrations like those described in the referenced paragraph; mechanical vibrations from the environment traveling through solid surfaces like rack vibration, transformer hum, component electronics; and airborne vibrations. HAL-O III damping instruments effectively and audibly reduce the detrimental effects of all three.

http://herbiesaudiolab.net/ultrafq.htm

Steve
Herbie's Audio Lab