Do you guys think the old aluminium cylinders are good heat dissipators for tubes?
What's your advice on this?

I don't know about the aluminum ones. But I was taught that heat in any electrical device shortens its life. So my guess if it keeps the tube cooler it will have a longer life.

Many tanx for the input, speakerman1.

Since nobody seems to know nothing about "old aluminum" heat dissipators here's a pic of two of them that i found in the trash , and, that's the reason of my question.



The two aluminum heat dissipators are the ones with some blue light in the bottom. In the rear are vacuum tubes or valves. I think you all know what tubes are...??!! if not a put a better pic.

Many tanx in advance.

Clint E.,

On my Jolida JD-9 the 12AX7 tubes are enclosed in aluminum tubes similar to the ones you have pictured. Jolida did not advertise them as heat dissipators but instead as EMI or RF shields. From my experience, I didn't like the way their aluminum tubes "trapped" the heat generated from the 12AX7 tubes so I removed them and didn't hear any adverse effects in my system. I feel that keeping the tube "free" of any obstructions to vent the heat probably works best. If heat dissipators really worked then I guess we would see many more tubes with these "heat dissipators" on them from preamp and power amp manufacturers. Instead, I have had much better results using Herbie's Audio Lab tube dampers to stop vibrations that could affect the tubes and ultimately the sound in my system.

Slbenz

Here's a photo of some different tubes and shields/heat dissipators. The one on the left is a tube and cover out of an old Sears guitar amplifier. The bottom is flared and actually snaps on the outside of the tube base, not touching the tube itself. I don't know if it shields from heat, electrical interference, or both. The tube right next to it in the unit has the same base, but no shield. (maybe it's lost) Other tubes in the unit have none, nor the accomodating base.

The second tube/shield is out of a military radio. As you can see, it it two piece, and the liner and cover are both made out of aluminum. They slide over the tube and are actually in contact with the glass. The third (larger, but similar) is also out of the same radio. There is a cooling fan in the unit, and they are prone to heat damage, so I assume the louvers in the liner are to both circulate air and dissipate heat.

The units you have, clint, appear to be just thin aluminum sheet that is seamed and made to slide over the tube also.

For you tube buffs, I just went out and pulled the tubes out of the amp to see what they were.

2 ea. 12AX7A "Silvertone" (Sears in-house name) made in USA
1 ea. 6AU6A "Silvertone" made in USA
1 ea. 6X4 "Realistic" made in Japan
2 ea. 6V6GTA "Realistic" made in japan

Many tanx for the input, guys. Very good info in your posts.

Maybe i'd found another way to dissipate heat...take a look at the pic :



I find that using a heat dissipater from a computer processor, maybe i'll can dissipate some of the heat came from the transformers and also from the valves, too.
Later, i'll try to put a small no noise fan, to increase heat dissipation.

What you guys think of this?

Lesser heat - better performance.

Computer fans are fantastic. No noise at all.



I must get two of these fans.



Later i will measure the temperature with and without the dissipator.

The only thing you can do to dissapate heat is run the amp in a cool room. Heat from anything is ultimately dumped into its surroundings. Therefore it's the air temperature that regulates how much heat can be dissapated. It controls the equilibrium but not the rate. For example, even when the tube is off, it will get no colder than the room -or- it will literally start cooling the room down until you reach an equilibrium. Heat always flows from hot to cold, not vice versa.

As for the rate (to reach theoretical equilibrium), I don't think that aluminium would make a bad heat sink, but its important to have a lot of surface area around it, so that it can dissapate as much heat as quickly possible. It's a pretty good thermal conductor and therefore would be ok. However, keep in mind that most of the heat dissapation will occur by convection. Hot air rises. Therefore, blocking off the top of tube is probrably not a good idea.

Tanx for the imput xxxrv.

But, i'm not using the old aluminum tubes anymore. I concur with slbenz on the use of that tubes as shields against EMI or RF shields.
I already increase heat dissipation with ventilation - a better form of dissipation than convection - with the comp processor heat dissipator in the top of the amp transformer's; and because my room temp is around 20ºC and the amp temp is around 40-45 ºC - the pic below - imo i think i can take off "some" degrees.




Tomorrow i'll measure the amp temp with the ventilation on.

I don't have much knowledge in tube care so take what I say with the proverbial grain of salt.

The small signal tubes have a life expectancy measured in thousands of hours. If they are quality tubes. Not so with the large power tubes. So a few extra degrees of heat added by a tube shield is virtually meaningless IMHO.

The shields are usually on the 12AX7's which can be microphonic and subject to RFI. On some if you tap lightly with a pencil you can hear the sound amplified through your system.

I leave the shield in place on the 12AX7 in my mc-275 and don't notice any extra heat buildup of consequence. If you use a fan I've been told to have the fan pulling air past the tubes rather than have the fan blow directly on the tubes.

If you want a fan you can find a computer fan and what I did was choose a fan by noise output. I run my 12v fan at 9V and the SPL is 12db. Which translates to I can't hear it even on quiet musical passages

Some places sell fancy neoprene\silicone rings to stop tubes from picking up stray noise. They probably work but I can live without them

BTW, very nice looking gear Alvarro.

On my SET amp at home, I only use tube rings. No need for heat dissapators. My amp is on the top shelf of my rack and I think that's enough for me. My comments above were intended to enlighten more about how heat transfer works. Frankly, I've used heat sinks before on other electronic equipment, but my tube amp doesn't run the risk of generating as much heat in a small area as say compared to a pockels cell (laser beam chopper in the mhz feqs). When you've been running one of those for 12 hours and you can feel the heat dissapating from the blades of the heat sink, that's when you know you need to keep your equipment cool. It actually would become uncomfortable to the touch. If you want to talk serious heat dissapation, the laser that used along with it drew 400V of juice to produce 300mW of UV laser light. Most of the heat went into running water than came from an umbilical through the laser. Could burn a piece of paper with the laser light in no time. I think there is at leat one tube amp company that insulates their tubes with water or oil. If you check the CES coverage in stereophile you may be able to find it their. What a waste of engineering...but if you have to have it....well....YMMV

Many tanx for the input guys.

M Gibson, i already use a comp fan as you might notice from the pics i posted. And you're right no noise at all.

xxxrv, i know exactly how heat transfer occurs because that's my line of work - i'm a air conditioner mechanical engineer - but, tanx anyway for your wise advices.

This all began because i'd change the power supplies caps for ones bigger and from Jamicon. I don't know if it was my impression or not but in terms of heat temp. of the amp i kind notice a little increase of temp around the unit.
That leaves me to think about means to dissipate that extra heat...

With the new caps i have much more tight low end than before.
About this heat dissipation system, it's possible that it doesn't have any real impact on sound...?! , but i'm sure - as you know - that a transformer ( or any electric /electronic device ) lasts longer and works better with less temperature.
...and it's fun doing things, experiments around our hobby; if it works, that's good. If not, no worries.
I like to try different things and new approaches to the things i love.

Later i'll measure the amp temp with the ventilation on.
Maybe i'll get another comp processor dissipater this afternoon...

There is a pervasive belief that hot transformers sound better. This must have started because audio lovers believe there must have been a sonic reason why manufacturers ran them so hot.
But, increased temperature means increased resistance and less conductance.
The best vintage designs that were built for reliability and had potted transformers, ran at room temperature.

I know that a Push-pull output and power transformers can run hot, like mine. IMO, that's because the Chineese manufacturer wanted to save money and used a core size that lets the transformer get quite hot.

Also, there's another issue with "quite-hot" transformers :
- Condensation.
When we shut down a hot transformer, condensation takes place and the resulting could be water droplets forms in the transformers windings, on the inside of the bell ends and at the lead wire/magnet wire solder joints...

So, in resume what started as kind of fun around tubes heat dissipation ends up in a serious subject about the heat in transformers.

I'd measured the temp outside of the potted transformers with the "ventilation" on, and temp dropped 20ºC . Incredible what this little thing can do...

Just an update.

Sometimes the best solution to a problem is the simple one. If imo the problem of a potted transformer is heat, now i have non-potted transformers.
I mean, i took off the metal box where the transformers were
enclosured.



Next week i'll make a lot of holes in the box and then i have real ventilation passing through the transformers.

Than i post some pics.

After all, the solution is a simple one.