Silicone tube dampers

[krellmk]

Are these things snake oil or what some of these audiophile swear these thing improve the tube sound

 

[J!m]

Go to McMaster-Carr and find appropriate size silicone o-rings and see for yourself.

A bag of (many) will be ~$10.00

I put some on my Counterpoint amp tubes because we have tons of o-rings at work and I was putting new tubes in anyway...

 

[krellmk]

So what is the end result

 

[Skratch]

They probably help on high gain stage tubes playing at loud volumes

 

[J!m]

For my ears, I can't say. Only because I put new tubes in both amps along with the dampers, at the same time.

The CLAIM is that microphonics are reduced. And, I can see that, if say the amp was mounted in your truck going down the road. But with a VERY heavy amp, sitting on the floor, I don't think it does much, unless the speakers are enough to excite the board in the amp. And maybe they are?

There is some science behind the idea, but audibility is sketchy at best. I mean you can usually hear it if you rap on a tube.

As I said, in my case it was "free" and "why not" so I did.

 

[Lazarus Short]

I made a pair out of some sorbothane scraps for a couple of preamp tubes that don't run hot, but I don't know if they work. It was cheap, at least.

 

[mr_rye89]

I wouldn’t bother unless the tube is obviously ring-y. Like those low voltage miniature tubes in 1940s battery radios (3s4, etc)

 

[J!m]

I see it the other way- it can't hurt, and it's very cheap to do.

Tell me the diameter of the tubes in question and I'll give you the dash numbers to order.

 

[krellmk]

Some guy at a audio show in NYC told me it help to reduce second-order, "harmonic" distortion, why you want to remove this harmonic which is quite musical.

 

[Skratch]

Some guy at a audio show in NYC told me it help to reduce second-order, "harmonic" distortion, why you want to remove this harmonic which is quite musical.

Did he try to sell you the Brooklyn Bridge

 

[J!m]

I already bought it.

 

[krellmk]

One look at me he know my pocket was not deep

 

[D-500 Flogger]

Some guy at a audio show in NYC told me it help to reduce second-order, "harmonic" distortion, why you want to remove this harmonic which is quite musical.

krellmk,

I enjoy attending audio shows almost as much as I enjoy live music. The former because I can never predict what I will hear from man or machine, and the latter because, well, for reasons that I will never understand completely, music just makes my mind go happy. :0)

In this video, with no music playing (thereby negating the musically-stimulated 2nd harmonic theory) you can hear the actual mechanical resonant frequency of a piece of metal inside a vacuum tube. The source of the noise must be at least one of the 4 items in a triode: heater > cathode > control grid > plate. If I had to make an educated guess, the physical implementation of a control grid is such that it would be the 'flimsiest' & therefore most microphonic of the 4 major parts involved?

In order to hear for yourself what I'm trying to describe, please open the video below & skip directly to ~8:40, and listen carefully to the ~30 second demo/description:

NOTE: Bonus points if you go back to the ~8:10 mark & listen to the constant hiss created by the 1st amp.

Anyway, hope this helps explain what we're up against when using tubes to amplify music signals. (Well, at least with cheap tubes...no doubt the genuinely well-engineered tubes don't suffer from these microphonic sins of amusical addition. :0)

Cheers --

3D

 

[D-500 Flogger]

In this video, with no music playing (thereby negating the musically-stimulated 2nd harmonic theory) you can hear the actual mechanical resonant frequency of a piece of metal inside a vacuum tube. The source of the noise must be at least one of the 4 items in a triode: heater > cathode > control grid > plate. If I had to make an educated guess, the physical implementation of a control grid is such that it would be the 'flimsiest' & therefore most microphonic of the 4 major parts involved?

3D

Check this out -- curiosity piqued, I dug a little deeper and actually found (from back in the heyday of vacuum tubes) a scientific study where they quantified the microphonics of the different components inside the vacuum tube vs frequency:



Given the high-frequency ringing we just heard in the video, I think this correlates to the upper freqs in the "Cathode and control grid" section in the lower right hand corner of Fig. 4. Note: mr_rye89 correctly called the 'ring-y' nature of the sound, which the video corroborated.

(Refer to the attached .pdf file for the article that this chart came from -- a very informative read.)

Quoting the last sentance of the 1951 article:

"Thus the design of a low-microphonic tube is a long and arduous process, and research continues to produce truly non-microphonic types. "

****

The bottom line is, if we're gonna run our tunes through tubes, then we gotta figure out how to pick out the stuff that's not only pretty...but sounds even better than it looks. :0)

Cheers --

3D

 

[krellmk]

Had 6922 phono preamp you could detect a slight microphonic when i used MM it was worst when i use a MC with a SUT

 

[J!m]

I just avoid vacuum tubes.

They are only in the pre driver of the amps, and run well below nominal. The only reason I changed them was so that I had matching tubes across both amps- my original one had the original tubes (still fine) and the other had different tubes. Michael Elliott was a fan of the Sovtek tubes, and I was a dealer prior to acquiring the second amp… got me two matched sets, threw o-rings on them and enjoyed the music.

The comments above about the phono pre are good reason to avoid them in that device. Such huge gain from such a tiny signal. You either have a half-dozen gain stages (with the additive distortion from each) or fewer with massive gain in each. Op amps are perfect in this scenario because they are so small it is very easy to optimize the power supply close to the chips. Even a discrete assembly sufferes from space- it needs room for components!

As an aside, I asked Wyn about designing op amp based drop in modules- similar to what Mark used in his early gear, which was directly stolen from their use in mixing consoles. You unplug one module, and then plug in a new one if it goes bad. Gets you back up and running when time is money. But he refused, since there is no point being tied to that discrete-based architecture when modern op amps are quieter, faster and cheaper.

 

[Gepetto]

I just avoid vacuum tubes.

They are only in the pre driver of the amps, and run well below nominal. The only reason I changed them was so that I had matching tubes across both amps- my original one had the original tubes (still fine) and the other had different tubes. Michael Elliott was a fan of the Sovtek tubes, and I was a dealer prior to acquiring the second amp… got me two matched sets, threw o-rings on them and enjoyed the music.

The comments above about the phono pre are good reason to avoid them in that device. Such huge gain from such a tiny signal. You either have a half-dozen gain stages (with the additive distortion from each) or fewer with massive gain in each. Op amps are perfect in this scenario because they are so small it is very easy to optimize the power supply close to the chips. Even a discrete assembly sufferes from space- it needs room for components!

As an aside, I asked Wyn about designing op amp based drop in modules- similar to what Mark used in his early gear, which was directly stolen from their use in mixing consoles. You unplug one module, and then plug in a new one if it goes bad. Gets you back up and running when time is money. But he refused, since there is no point being tied to that discrete-based architecture when modern op amps are quieter, faster and cheaper.

A wise response