• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
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    the safety precautions around high voltages.

Tube Dampers

That's the project. I intended to use good parts: MIT RTX caps, Elna Cerafine, Jensen copper foil caps, Holco, Caddock, Allen Bradley resistors and of course the dampers. The dampers were available from Sonic Frontiers, so I think they were for real. SF was sellin them at discount for $65. I never have an opportunity to try them thou. Maybe someone on the forum did?
 

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Tube Coolers

Bill Perkin's tube coolers act as dampers as well, cost a whole lot less than these top hats, keep the tube cooler (ie for longer life), and are available at the new Parts Connexion. A pr can be seen on my 5-Buck Amp.

[IMGDEAD]http://p10hifi.net/tlinespeakers/TLS/tubes/images/5B_fr_size.jpg[/IMGDEAD]

Bill also makes isolated tube sockets that minimize microphonics which with the tube coolers make an excellent combo.

A pdf paper on the sockets [360k] and one on the tube coolers [230k].

dave
 
Peter Daniel said:
I am sure that if you combine Top Hat Dampers with tube coolers you will achieve even better results on a road to audio nirvana.:)

Not a bad idea... wanna swap for some mumetal

And if you had a 100-Buck Amp you might think twice about obtaining them.;)

Parts are collecting... i have a set of large [like Audio Note size] East German EL84 OPTs, some fresh 6N1Ps, a PS out of a Baldwin organ that should be bigger enuff than it needs to be (was used to power 35 'AU7s, an equal number of 'AX7s, a pr of 6L6s + a few other tubes), and some cryo-treated EL84s. Now i just need to get the summer-around-the-house-chores done and free up some time...

dave
 
Re: Cryo treated EL84's?

Circlotron said:
I've never heard of that before. What is it meant to do?

The tubes are immersed in liquid nitrogen for 12-24 hrs. One of those things that some put in the snake oil classification, but it does make improvements in tubes (or weeds out flakey ones), caps, cables, switched attenuators.

This thread is pushing for its 3rd Perkins Paper so here is the URL to a whack of them -- Cryovac is the one of interest here.

some of Bill's Papers

dave
 
Dennis Boyle told me basically how he does that, pretty tricky and I bet a lot of tubes are lost to breakage. Never heard them myself but have Cryo OFC interconnects. Amazing how changing the crystaline structure of a metal can change the sound. Thats the reason a lot of guys like to anneal their silver wire I guess. I did a lot of silversmithing and the annealing process is a must for cold forging. You beat something with a hammer and it compacts everything till it will crack. You put the fire to it before it cracks and the heat excites the molecular structure enough that they kind of spread out from each other and the metal is soft again so you can whack on it some more. I think but am really just guessing that the controlled super cooling and warming back up in cryo treating gets things lined up and close in a crystaline way the same as the hammer does with silver or copper sheet. And if you don't do it right it will crack.(meaning the metal) The hard part about tubes has got to be that glass is a frozen liquid and fast temp changes will shatter it and different metals will contract and expand at different rates.
 
Microphonics and Damping

Very interesting idea, adding a little mass to the shell of the tubes!

I recommend dampeners for high-mu areas of your amplifiers, especially the phono stage tubes!! I use a pair of little sorbothane rings on the 6922s in my trusty Counterpoint 5.1. The heat generated by these tubes does attack the sorbothane over time, but the microphonics are effectively squelched by the rings.

I am using the high gain mode, as I'm using a low output MC cartridge; prior to the dampeners, I could hear even slight thumps of the chassis.

Has anyone experiences with the metal dampener hats?

Bob
 
Back to the Cryo

Evidently this process does something along the lines of what the aging process does. Metals tend to reform back to original structure over time. Memory it is called. A tube that has been sitting on a shelf for 50 years ought to sound better than one made yesterday as everything has realligned itself so to speak. The Pearls (which are not immersed) go through a 4 day chilling and warming back up and it evidently speeds up the memory process. This is as was explained to me by Dennis Boyle this evening. Conjecture or logic? He told me that he listened to a pair of Pearls that were of a type he normally dislikes and that there was a definate improvement. I also found out that cryogenics is used on guitar strings, some musical instruments and to improve the accurasy of match grade rifle barrels. Cool!

I have only used old military tube dampeners and there was a definite improvement in prevention of harmonics in the high gain EF86 triodes. A friend has been using the same type on some 12AU7s and he reports that he is getting clearer amplification but it seems to have lowered the gain a bit. Those hats ought to work.
Where do we get sorthobane rings?
 
Re: Back to the Cryo

Thatch_Ear said:
I also found out that cryogenics is used on guitar strings, some musical instruments and to improve the accurasy of match grade rifle barrels.

They will also take a fully built race engine, cryo it and get something like 10% more power out of it.

There is also at least one pre-amp out there where they cryo the whole thing (they don't tell anyone because they figure it gives them a secret ingredient).

The guys in hawaii that sell the DACT stepped attenuators sent Bill 2 units. He cryoed one, left the other. Marked them so that you could tell one from the other. Sent them back (only he knew which one had been in the Nitrogen). They picke dthe cryoed one as clearly better...

dave
 
Hi Dave, interesting about engines giving 10% extra power.
How does that work ?.
I was told years ago that when Rolls Royce cast an engine block, that they leave it out in a paddock for ten years to let it thermal cycle and stabilise, before taking into the milling shop.

What is the cost of this cryo treatment ?.
Hmmm, next time I go to the local doctor, I might ask if I can drop a few transistors into the liquid nitrogen cryo vessel in his surgery.

Are autoshop O'rings useful as tube dampers ?.

Eric.
 
mrfeedback said:
interesting about engines giving 10% extra power.
How does that work ?

I'd only be guessing. Thatch_Ear had some good comments. With the kinetic energy of the molecules way lower, the natural atomic forces would have a better chance of playing a role at aligning atoms into more regular order i expect.

What is the cost of this cryo treatment ?

I'm not sure. My tubes & coolers were a reward for helping Bill put together an order of coolers headed off to England. I originally met Bill because he was the guy building the boxes for the Radford S90s that got me going on transmission lines some 25 years ago.

Hmmm, next time I go to the local doctor, I might ask if I can drop a few transistors into the liquid nitrogen cryo vessel in his surgery.

Usually the process is done slowly over many hours or days, Just popping them into the LN might cause them to "pop". Worth a try thou.

Are autoshop O'rings useful as tube dampers ?

Worth a try if they don't melt. If they do melt you could have a bit of a mess.

dave
 
O-rings??? Hmmmmm....

Sorbothane is amazing stuff. It is like a resonance "sponge". I have some very cool sorbothane feet with a spun aluminum "shell" around each unit. The quartet of feet effectively dampen my preamplifier. No more thumps, as well as the "ping" sound as the control switches are toggled.

Granted, the gain has to be cranked up a bit, as in a quiet classical recording, but I know that feedback is happening in the loud passages. Kind of an expensive spring reverb, come to think of it...

The tube rings are mounted about two-thirds up from the base of the tube. They are about 6mm wide, with a square cross-section. If I remember right, someone like AudioQuest made them. I'll research it for the group.

I think that a dense automotive O-ring would have much less effect than these rings. They're simply too hard, and not as heavy as the Top Hats. If one wishes to dampen with metal, it should be of larger mass.

Bob