Tube dampers

[Joe Appierto]

As I stated before, CJ supplied a pair of O-rings for each tube for the 17LS (so 8 in total) and the 16LS2 (12 in total). The Owner's Manual for each preamp said to place one at 1/3 from the top of the tube and the other at 1/3 from the bottom. That'd correspond to the top and bottom of the plate structure. I agree with Roberto, in that if there was any difference in the sound using them or not it was difficult to detect but I don't think CJ did that for the heck of it.

[SteveFord]

I always wondered about the Pearl tube coolers found in my Sonic Frontiers preamp.
https://www.pearl-hifi.com/03_Prod_Serv ... olers.html

I figure they put them on there for a reason but I've heard other people say don't do it, it's like putting a winter coat on a polar bear.

[AnotherJohnson]

The shields I’ve been mentioning can also reduce glass temperature, although the Pearl style has an even greater heat dissipation surface area due to the fins. Heat leaves by conduction, convection, and radiation.

So the coolers and the shields reduce microphony and temperature , giving you a “twofer.”

My guess, and it is a guess, is that a tube that is microphonic will respond positively to damper, shield, or cooler.

Another guess, is that lowering the tube’s glass temperature may affect the tubes performance too.

And I would expect tube life to failure would also be affected by temperature.

Some big amps have to have cooling fans. Some use extensive fin systems. Virtually all manufacturers tell you to allow space for adequate ventilation. Electronic components virtually all age out more quickly if they’re in a hotter environment than they were designed for.

The dampers are harmless. The shields are harmless. The coolers are probably harmless. There may be some circumstances where there is benefit to their use.

They provide a whole new playground …

[AnotherJohnson]

As I stated before, CJ supplied a pair of O-rings for each tube for the 17LS (so 8 in total) and the 16LS2 (12 in total). The Owner's Manual for each preamp said to place one at 1/3 from the top of the tube and the other at 1/3 from the bottom. That'd correspond to the top and bottom of the plate structure. I agree with Roberto, in that if there was any difference in the sound using them or not it was difficult to detect but I don't think CJ did that for the heck of it.

I have now run across an owner’s manual for the TEA2MAX that mentions them, but the current version on the web site does not. TEA1 manual doesn’t appear to either.

Joe, I respect your ability to perceive small changes above my own. If you struggle to hear a difference, I think that means that the unadorned tube was a good one, and there was no audible microphony to mitigate.

Suspenders and safety pins. Polar bear with overcoat. As you like. Whether you have these tweaks or not is part of the fun.

Bill:”Lew should we put those red o-rings on the Premier line?”

Lew: “Sure. They add $.30 to the price of the preamp, but they look cool. Plus Bill Johnson is using them, and so some customers will expect them.”

Jeff: “I dunno … I guess we can. The extra labor adds another quarter, but we’re still below the chump change level. Herbie tells me we can add $120 to the retail price if we use his rings.”

Bill: “Maybe we could source them as precision laser cut proprietary dampers from our metal film resistor supplier in Israel. That would be something to market.”

Lew:”Nah. Our customers are smarter than to fall for that. The dampers don’t really make the music sound any more right. Remember, we use first quality tubes. No need to venture into the valley of BS. Our credibility and integrity are important.”

AJ: “My apologies. I said I’d let it go, but I’ve posted. Mea culpa.”

At ease. Smoke if you’ve got ‘em.

I love you all. Especially Bobby, Joe, admin, and RJ.
I’m wishing all of you happy holidays!

[Joe Appierto]

It's all part of the fun.

Merry Christmas and a Happy New Year!

[roberto]

Chicos,

I do follow the instructions of the o-rings. My Classic One Twenty SE came with two o-rings for each 6922 and Joe is right about where to located them into the tube. Same thing with the ET-7.

There must be a reason why to use them. I use them. There is a lot of blah blah about the inner detail and the micro-dynamics are enhanced. I took them off and honestly, my ears do not detect that huge difference that the manufactures claim. But, I like the idea that they make the tube anti-resonate (?) so I can confirm that they do work in this respect. I know that I should not do what I did, but I was curious. So, I increased the volume at the preamp, without the top cover, and tapped the tube with a pencil. It reduced a lot the noise while tapping the tube with the o-rings.

We love you too AJ, and Admin, Joe, RJ and all the CJ members that have the patience and tolerance with this old Wolf. God Bless all you!

[roberto]

Here is an o-ring small tube damper that was into an Audio Research power amp. It just began to get melted.

9A28FB76-91AF-4F4F-87BF-9A65DB29B255.jpeg (2.4 MiB) Viewed 3266 times

[AnotherJohnson]

Those look like worn out versions of these.

https://www.ebay.com/itm/3M-vacuum-tube ... 632-2357-0

They’re in an ARC piece of gear, but not OEM.

[admin]

I wonder if they lose the temperature resistant properties with time? You would think that tube dampeners would be designed to operate at temperatures well above what tubes typically achieve.

[AnotherJohnson]

I wonder if they lose the temperature resistant properties with time? You would think that tube dampeners would be designed to operate at temperatures well above what tubes typically achieve.

They are. I gave the specs for a typical custom order above.

You can buy all sorts of stuff and stick it on after it leaves the factory.

ARC small tubes typically have a life much longer than CJ … they claim 4000 hours, and generally ARC preamps have much less gain, which probably contributes to the longer life. CJ is typically getting 25 dB. Unbalanced ARC is typically half that gain.

OEM dampers are an elastomer, typically silicone based to withstand the heat. Those in the photo don’t look like any I’ve seen OEM for ARC.

I’ve never said o-rings sold as dampers can’t melt, or start to melt. What I’ve said is that OEM ARC dampers don’t melt unless there is some other issue in play that has led to excessive temperatures.

Obviously old elastomers can age out. They’re installed in a hostile environment. You can’t make a rational case for the idea that CJ is smarter about picking dampers than ARC. ARC is a heck of a lot more consistent in using them, and they’re not stupid.

[roberto]

I am waiting fora worse transparent o-ring into an ARC amp. Here in CR they melt in a such way that you need a knife to remove it. Only in the ARC I have seen. And yes, it looks like a aging material fatigue.

[AnotherJohnson]

Don’t scrape the bogus o-ring off … toss the tube. It’s been despoiled.

I wonder if tube dampers are controlled by the importer. Usually importers are required to support the product by providing warranty, service, and parts.

As I’ve dug around, I’ve found quite a few ARC aficionados recommend against tube dampers unless the tubes are microphonic. They have a negative effect on heat transfer.

I don’t dispute that you find melted o-rings on ARC installed tubes. After the product leaves the factory, anyone can install anything. And CR is probably more challenging than many places to assure the unit is properly cooled.

The LS28 owners manual made a point of assuring proper ventilation in the installation. And the LS28 itself has extensively perforated case work to facilitate air flow.

[roberto]

The first thing that I tell a customer when he has tubes, is to use the right ventilation. It is very wise to have air flow. I do believe that the problem definitely is due to ageing. The material had lost their properties.

We all know that small tubes are microphonic and there are brands that this microphonic is much less. I only have seen this meted o-rings into the ARC preamps and power amps. They are old stuff. Customers are known too, that inside of any tube components there are lethal voltages. So, many of them do not touch anything inside.

[roberto]

And also some customers are very greedy and they don't spend money on new tubes...they believe that they last forever. This is not the case for all, but a high number of customers don't realise that tubes are not forever. Or their ears are not too good, or they are very greedy.

As soon as the unit is in my hands, the first thing that I do is to test the gain on both triodes (usually used) and sometimes a level difference with one channel vs the other channel is the gain. Once I have measure this, I take a listen to hear if the unit exhibit a problem or how is the quality sound. Also I apply a signal by tones starting with 50Hz to 20KHz at -20dB of the reference level (0dB= .707 V @ 1Kz reference level) and measure the frequency response.

[roberto]

I wonder if tube dampers are controlled by the importer. Usually importers are required to support the product by providing warranty, service, and parts.


These o-rings came from the ARC factory, inside the carton box with a separate box where the tubes are.

[AnotherJohnson]

These o-rings came from the ARC factory, inside the carton box with a separate box where the tubes are.

I just finished reading the book published in honor of ARC’s 50th anniversary.

According to the book, published in 2020, ARC has had 2 “official sound evaluation listeners.” They hired #2 so that he would overlap with and be trained by #1. #2’s background came up via a tweak oriented path, so he appears to have been gifted with good audio discernment. He’s been there since the mid 90’s.

In any event, in the book this official sound evaluator says that they discovered that tube dampers helped reduce microphony in the small tubes. He says that it took them a while to find dampers that would work best. His background is materials, so maybe they experimented with things that weren’t up to the task. I think these experiments started around 25 years ago. Once they sorted it out, he claims they hold up in the hostile environment.

The pictures in the book show black, round cross section O-Rings. They look just like the ones supplied with my new REF 75 SE. and in the pictures, the two rings per tube are installed touching each other and at the level of the getter.

FWIW, the book is quite informative. It’s really an oral history of ARC as told by the major players over the 50 years.

[admin]

I like reading audiophile history. May have to pick that book up. I recently finished "Schiit Happened: The Story of the World's Most Improbable Start-Up". It was an interesting read and very insightful about all the random things that have to happen to start a new company with a non-orthodox approach to the audio market.

[AnotherJohnson]

I bought it here after picking up the used LS28.

https://audioresearch.com/audio-researc ... usic-glow/

It’s written/compiled by Ken Kessler. It is of high quality, hard bound, glossy, over 200 pages, large format.

I learned quite a bit about the company and the people. It was not puff and pablum. I don’t think they sugar coated things. William Z. Johnson was a year older than my Dad. He joined the Army out of high school, and served for the duration, as did my Dad. He came back from WWII (Army Signal Corp) and went to work by opening a TV and radio repair shop. He built it into a high end high fidelity store, and started building and customizing amplifiers. He didn’t use his GI Bill benefits until 1968 when he sold his company and took time off to learn to fly. He then worked as head of R&D for the conglomerate that had bought him out for two years.

In April of 1970, flabbergasted at the mess the conglomerate was making, he reacquired his patents and his freedom by taking on the approximately $80k in debt the conglomerate had rung up. They kept the name “Electronics Industries.” Bill renamed his newly formed company “Audio Research Corporation.”

In any event, I still view the tube dampers as a tweak that can’t help if there’s not an existing problem with microphony.

But … the book is good if you’re interested in ARC, or the personalities in general. It includes lots of first hand accounts, in an interview style.

I looked at the QC cards in my LS28 and REF 75 SE. Sure enough, the #2 Chief Listener’s initials are in the box for the evaluation before heading to shipping.

[AnotherJohnson]

On a related gem from the book, the chief listener asserts that they cryogenically treat the AC input … because it makes a difference.

[roberto]

Are you now a believer?