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Tube amp heat risk?

post #1 of 9
5/24/08 at 9:17am
Thread Starter 
I live in Australia and it can get mighty hot and humid here during the summer. up to around 37 degrees C at its extreme end. Are there any risks of extended usage of tube amps at this heat?
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post #2 of 9
5/24/08 at 10:59am
I used to live in the South African highveld where we would regularly see 40deg C, had my vintage tube amp running daily without any problems. The only concern I could see is melting some of the wax out of the old transformers but that would take a lot more heat..dB
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post #3 of 9
5/25/08 at 1:16am
AFAIK tubes aren't really heat-sensitive devices. A difference of 10C or so isn't much when you consider the tube heaters are glowing at maybe a thousand degrees or so. Heat dissipation won't be affected that much, the tube envelope will just be a few degrees warmer.
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post #4 of 9
5/25/08 at 1:27am
Yep, no need for a heatsink, or fans, or liquid cooling. (at least at the moderate levels of AF amplification we are dealing with)

SS devices are far more sensitive to heat, don't sweat it. No pun. lol.
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post #5 of 9
5/25/08 at 1:35am
Only if you can stand the extra heat in the room. Tube operating temperatures are above that, so the ambient heat doesn't do much. Still, it wouldn't hurt to have AC or a fan going.

I've run tubes down in Phoenix and Yuma, Arizona. If my calculations are correct, they get over 52 degrees C in the summer. As the saying goes, it's a dry heat.

And be sure to drink plenty of water!
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post #6 of 9
5/25/08 at 3:02pm

Installation?

You don't say anything about your installation. Is the amp freestanding or in a cabinet? Are the tubes covered by a grill or open? While I agree generally with the posts above, a tube amp in a cabinet with a grill covering the tubes can get hot enough to shorten tube life (and the heat can affect other components). This is why, for example, Audio Research puts fans in their very expensive tube amps.

The best solution, if you don't have children and your spouse doesn't mind, is to use the amp out on a table or stand with the tube cage off. If you do this you shouldn't have a problem in any room you can stand to listen in.

But if the amp is in a cabinet you should use fan cooling to keep the heat from building up around the amp. There are many good fan solutions out there as a result of the pc gaming and home theatre craze. Everything from professional looking side exit fans for use on top of components in cabinets to cheap but very quiet 120mm computer fans.

And I must admit that when I run powerful tube amps in the heat of summer I put a little fan a couple feet away from the amp and blow air at low speed over the power tubes. But I do that because ... well, because its a guy thing.

Regards, James
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post #7 of 9
5/26/08 at 12:23am
Thread Starter 
Thanks guys, really hit the nail on the head with those answers, Ill probably run some computer fans to be safe - no harm in it i guess.
cheers guys
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post #8 of 9
5/26/08 at 12:59am
Not to mention one of the best things about having a tube amp is to have the pretty glowy tubes out and visible where you can see their eerie light!
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post #9 of 9
5/26/08 at 1:47pm

One Other Thing

One other thing -- if you use a computer fan on top of a tube cage or ventilating holes, you always want the fan to suck, not blow.

This is critical for any component that has an internal fan -- if you blow air into the component you can actually cause it to overheat and damage itself, because you can fool the temp sensor that triggers the internal amp fan into thinking the inside of the amp is cooler than it really is.

So while on my McIntosh 275 amp, for example, I may have a fan blowing at low speed on the output tubes (with the tube cover off), on my PS Audio Premier power regenerator (which is just a different kind of amplifier and which has its own internal, but way too noisy fan), I have a fan on top of the unit over the vent slots, sucking hot air up through the amp and out the top.

Regards, James
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