Interesting article on Pearl tube coolers

pjdami

Supposedly extends tube life and reliability. Works on the "chimney" concept with extended fin design for increased surface area which helps heat transfer. I haven't finished reading all of the article myself but does provide some interesting data.

Anybody ever try any of these?

http://www.partsconnexion.com/resources/tubes/pearl_tube_coolers.pdf

RuSsMaN

I've been meaning to try them, just haven't gotten around to it.

They do have a cool 'look' when installed, imo. My scrounger has them on his Heathkit 70w monoblocks.

Cheers,
Russ

Tour2ma

Looks like something out of an adult novelty catalog...

Totally ignorant question...
Is there a temperature below which a tube's performance begins to suffer?

HBombToo

Good question Tour and as long as the temp of the cathode did not go below its optimum thermionic emission point I would not think there would be any harm. "No cathode sputtering"

What is spinning in my noggin is when designing a tube you must take into account thermal expansion from cold to operating temp for optimum performance of grid to anode and grid to cathode. That said, I could see cooling the envelope to the point that the operating specifications internal to the tube are not at the optimum.


Hmmm... got ta think some more on this.

HBomb

polkatese

Originally posted by HBombToo
"No cathode sputtering"

HBomb

Henry, could you explain this? I am interested to know what would be the symptoms/indication that overheating occured when it happens? I am interested because it might explain anomaly on my Philips when it is subjected to prolong playback (beyond 3-4 hours) without the cooling fan turned on. TIA, bud!

RuSsMaN

I think you'll probably notice more of an affect with driver tubes, 300B's, EL84's etc than pre / line tubes.

Sputtering? We aren't talking about tubes 'spitting' are we?

Cheers,
Russ

polkatese

Russ, I am curious though, what does it sounds like? crackling? distortion? shutdown? Without cooling fan, my Philips turns into a toaster even after an hour of play, and since it is modded, I know there is not enough room for the heat to dissipate enough without outside help. Net net is, I am concerned that it may damaged other components (i.e. DACs, transistor, etc.) that weren't designed to withstand that kind of operating temperature.

Or should I just put the *condom* on my tube for prevention?

pjdami

Thanks Russ for a reference on some one who is actually using these.

The reason I'm interested is obviously the claimed extended tube life as well as the claimed damping effects to reduce microphony as the article suggests. Kill two birds with one stone type of thing.

My Rogue tube amp has a 50 scfm NMB internal fan to provide forced convection on the tube section of the amplifier. It basically sucks in air from the top, draws it across the tubes, and exhausts it out the side. I bought the amp used at quite a discount and noticed after a week or so that the fan was kind of noisy. Dusty bearing I figured. I ordered a new fan, soldered it in and now I'm good. The fan is rated to operate at 28 db so it's pretty quiet.

I'd love to get rid of the fan altogether if I could by using these gizmos, but I would have to probably check with Rogue on that one. Or I could leave the fan in as well and improve the heat transfer, life, microphony, etc.

Yeah Tour, you bring up a good dilemma there. Unfortunately, ZOOM... way over my head on this matter. I could probably figure out the Nusselt number but that wouldn't help us would it;)

Tour2ma

LOL... I know it wouldn't help me. I was never a big fan of the dimensionless crowd...

Agree with Russ that it may be a bigger issue with hotter running output tubes.

Henry,
Here's one for you...

Since they are vacuum tubes, all of the internal heat transfer must be via radiant and not thermal conductance. So the operating temperature of the internals would not be affected by adding the coolers. The coolers could only impact the operating temperature of the glass.

Only bit that would fly against this would be thermal transfer to the base via the internal structure.

Make sense???

pjdami

Since they are vacuum tubes, all of the internal heat transfer must be via radiant and not thermal conductance. So the operating temperature of the internals would not be affected by adding the coolers. The coolers could only impact the operating temperature of the glass.

"puts on thinking cap" I agree with the first sentence since its in a vacuum. However, if the internals are one body that radiates heat and the glass is the other body which is assumed to be the receiver then if I remember correctly the equation for Q from body 1 to body 2 is a function of both body temperatures. So the glass being cooler would help the radiant heat transfer.

Man Tour you're going to make me have to go get my kern's book. LOL.. Good discussion though.

I like when we think....

pjdami

Wahla..

I have the solution....

Just buy one of those "miniature" Japenese trees and place it on top of the amp...LOL...

Wahhh...;)

Tour2ma

Kerns..... be a man and grab a Welty, Wicks and Wilson (the bane of my Junior year) or go for the maximum punishment with a Byrd, Stuart and Lightfoot... LOL. Until I read Kerns I never knew what it was to actually comprehend transport phenomenom.

You may be right about the temperature of the receiving "body". I honestly don't recall...

HBombToo

You guys are killing me. LOL

Tour you have a point but trust me when I say its not a true vacuum in the tube and probably at best 10^-5 or closer to 10^-4 Torr. Slower convection process but enough to say the least. Also a lot of heat is conducted through the base of the tube and I guess the gradient from top to bottom would vary from tube to tube.

A tube to hot is baaaaad... and a tube to cold is baaaaaad....;)

So cathode sputtering is when the the oxide coating on the nickle substrate is not yet emissive enough to provide the coulombs required in the conduction. When this happens the coating is literally ripped of the nickle and will deposit on cooler materials within the tube. The oxide will first settle on the grid then the anode and from there the tube is probably shot. or... better yet, If my boy was born I could throw down a six pack and really sputter.:D

Microphonics is an interaction between the grid and cathode and depending on how emissive the cathode is and how structurally stable the grid construction is will determine the microphonics. As vibrations in the room create a oscillation of the grid structure the tube will go in and out of conduction causing the ringing being amplified by the amplifier.:D

The distance between the cathode to grid and grid to anode are keys to a properly desighed tube. Structural integrity is also very important and when you buy a JAN spec tube it has met or exceeded all shock and vibration specs plus you can be assured the the cathode has not been tainted by any poisens like nitrogen.

Now keep in mind I'm not a tube expert and the bulk of my experience lies with Thyratrons, Maggies, Klystrons, CFA's and some TWT's and I'm just sharing that experience. For the most part a tube is a tube but until one lives it I can't say all criteria applies.

I'm still laughing over here and thanks for keeping me amused while at work.

Henry

organ

Very interesting. I agree with HBomb about the heat issue. I think the only area where they can be helpful is the reduction of microphonic effects. Pre amp tubes are more sensitive to vibrations so it might be a good idea to use them on pre amp tubes if you are having problems with yours. I've seen a device that dampen vibrations without acting as a heat sink. I think they'd be better.

Maurice

Tour2ma

Originally posted by HBombToo
...the coulombs...

Aren't those the clothes women wear that look like skirts, but are really shorts?

I hear you on the vacuum question... not absolute, so thermal heat transfer is still in play.

Regardless of where your tube experience comes from, that was a very nice write up...

pjdami

Regardless of where your tube experience comes from, that was a very nice write up...

Agreed. Nice writeup indeed.

We might just have to start calling him Professor Hbomb and the other one the "evil" twin;)

organ

Yeah, that was great. Let's just call him Prof HBomb. That evil twin is creepy.

Maurice

pjdami

I found an accompanying article which is a bit shorter and interesting as well. Kind of gets into what we were talking about above on the bottom right of page 2. It seems that the glass temperature control is what they feel is important for longevity.

http://www.partsconnexion.com/resources/tubes/TubeCooler_QuickStart.pdf

organ

Thanks for the link, Paul. Very interesting article. There's one thing that's still not clear to me. Wouldn't the temperature stay lower without the coolers because the glass is exposed to the air? I can see how heat sinks in SS amps are helpful at dissipating heat because the components are in an enclosed environment.

Maurice

pjdami

organ,

What I'm gathering here is that the entire thing is about controling the glass temperature (decreasing it). Since glass is a poor conductor it needs some help getting rid of the heat. that's where the extended fins come in. More surface area = better heat transfer. That's why even the SS amps have fins on them. Now add the fact that heat normally rises due to the lower density (due to hotter temp) and you have the so called "chimney" effect.

Even though the heat is lost from the fins though, it still needs to get "out of the box" at some point otherwise the air inside the amp will grow hotter eventually and the temperature gradient between the fin and the rising air in the chimney is decreased. Thereby, heat transfer will decrease as well.

Enough of all of this though. I'll look up how much of an investment they will be and see about getting some. Looks like they have done their homework.

organ

Thanks for the info. I get it now. But what if your tubes are located outside the amp?

Maurice

pjdami

But what if your tubes are located outside the amp?

Then it is better. the surrounding air of the room will be much cooler than the interior of a covered amp.

Probably why besides looking cool for tube amps (with the tubes exposed) it is also practical. My rogue amp has the tubes enclosed and that's why I figure it needs a fan to help out.

My Jolida cdp doesn't have a fan and is enclosed but it uses small signal tubes 12AX7s with one of the metal type heat sinks on them.

pjdami

Polkatese,

I'd really be interested to know what Alex at APL Hi-fi has to say about using these gizmos on the tubes inside your mod player.

My Jolida has a metal variant of these Pearl types .. same principle though. See upper right hand corner.

polkatese

Paul,

I'll check with him and see what he says, the only gizmo that I am aware of, that he puts on the Philips is this:

http://herbiesaudiolab.home.att.net/

How's the Jolida?

Btw, I am quoting a review from AA around the Little Pio (DV563A-S) that we spoke about before...thought you might be interested to read (don't know this guy, but I take he is a happy customer. It's a good review and meaningful comparison....

Posted by JayD (A) on April 08, 2004 at 18:43:49

For some context, I have owned the Sony SCD777ES for a couple of years in the past, and since (for the past two years) have had the Sony XA777ES. In addition, until recently I owned the Marantz DV8300. I still have a Marantz 8260. I had been attempting to improve the overall performance of my second system which includes video (sat tv and DVD). The system is comprised of an ASL Twinhead preamp, Welborne Laurel 300B SET mono amps, Adire HE10.1 signatures with Adire Rava sub. My other system, audio only, has an ASL Twinhead pre, as well, Welborne DRD 45 amps, Cain & Cain Abby speakers, with Cain & Cain Bailey sub.
In my efforts to improve the redbook in the second system (with the Marantz DV8300) I had owned an Audio Note 1.2 kit DAC with upgrades (oil caps and NOS tubes) which I didn’t particularly care for so sold. I tried a Shigaraki DAC, which I felt just created a different sound, not necessarily better. I then tried an AckDack which was easily the best of the three in my system, but I wasn’t entirely comfortable with it. I also tried a VSEI modded Sony 9000ES, but the low output was a bad match for my pre and I couldn’t get the best out of it. Feeling pretty frustrated with my efforts, I decided to try APL’s modded pioneer because it was inexpensive, it had a 10 day money back trial, and I had heard a stock version in a friend’s system where it sounded good enough to have potential.
I had the modded APL 563 for about 3 weeks when sent me an e-mail that he had upgraded the mod and would do it for free if I sent it to him. Before the second mod, I had liked the APL modded 563, thought it did detail very well, but also thought it had a couple of weaknesses. It seemed to be a bit receded in the mids, so that voices were further back in the soundstage mix than they usually are with most other players. Also, it could be a bit bright on top, depending on the recording. With the upgraded mod, the APL 563 more than remedied these weakness. Voices were now full and upfront, as usual in my system, but also conveyed subtle details missing from other players.
Until now my favorite redbook CDP, and SACD player, by far has been my Sony XA777ES. In direct comparisons with the Sony, on SACD there appears to be very little difference. The APL 563 was tighter and more extended in the bass, and seemed to be more extended in highs. On voice, the XA777 had a creamier sound. For example, hearing Alison Kraus sing New Favorite (on SACD) her voice is incredibly sweet and delicious through the XA777 - with the APL you can hear a little more of the inflections and her voice isn’t as sweet sounding (still beautiful though). But it feels like splitting hairs - they do seem quite close.
On redbook, it’s a different matter: when switching from the XA777 to the APL 563, I heard so much more in the recording that it would seem like almost hearing a different mix. With the 563, on redbook, it is easier to understand lyrics, hearing each pick on a guitar, subtle percussive effects. When I played Hail to the Thief (radiohead) and asked my wife to listen for differences, where she usually can’t pick up differences between players, she had no trouble at all in hearing the differences. She said that she was hearing things on the recording she had never heard before (she’s not an audiophile at all, just indulges me). That was the consistent experience I’ve had with it as well. On Damien Rice’s O (great recording by the way), on the cut Volcano, through the 563 the cello is more resonant, and you hear more of the body of the instrument, hearing the bowing more clearly; the brassof the cymbal comes across clearly; overall the sound is more rhythmic. I find myself tapping my foot or nodding my head more often (that PRAT thing) with this player. It does exceptionally well with classical as well. String instruments sound more tonally correct with the 563.It’s easier to sort out instruments in large classical works - e.g Turandot, Mahler’s 3rd.
Finally, on DVD-A, where before with the Marantz 8300 I found the DVD-A’s I had to sound sterile and uninvolving (I preferred my redbook versions), with the APL 563 they no longer sounded bleached out, but full, detailed and involving (I still prefer SACD’s, but the DVD-A’s weren’t far behind. The Classic DAD’s I had sounded even better - great sounding recordings, e.g. Sam Phillips and John Lee Hooker.
At this point, the APL modded 563 is the best digital that I’ve yet heard in my own system. A great bargain, I feel, at $695 total.
Reminder: this is just IMO, in my system, etc.

EDIT: Sorry for the digress guys! should have put this in Troy's thread on the Pio, but too lazy to hunt it down....