Tube amps and heat

cubdog

banging through drywall
I often hear complaints or observations about heat generated from tube amps. I'm curious as to which amps or tubes are the culprits here. I've owned two, working, tube amps an Onix SP3 using a quad of 5881s and my Shuguang which uses KT88. Neither produce significant heat in my estimation. Certainly not enough to avoid using in our hot mid-west summer months. I've used a portable thermometer to measure the air temp during and after use from a couple feet away from these amps and find no significant difference. So I wonder what are these "space heaters" and what kind of tubes are generating so much heat?

cubdog
 
Yeah I don't know what all the fuss is about. I have an ST-70 with EL34 tubes and an 2A3 SET amp. I don't notice the heat, but then I have AC running.


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my Fisher mono's can heat the place.i use a small fan to help now that summers almost over its not going to be an issue,mono amps equal twice the potential heat.my dynaco mono amps not so much as the fishers tho
hunter
 
In our old house - my music room was in the room with the thermostat and with the tube amps on (M125s) - the room would stay nice and warm - keeping the thermostat at at temp while the rest of the house would be cold.
 
I figure the quality of the music trumps any heat generated by my amps... except in the winter, then it's the best of both worlds... parking in front of the KT-88 tubes after being outside in January is a nice way to thaw out.
 
My Eico HF20 monoblocks running 6L6 outputs are pretty darn hot. It's uncomfortable to be a room with them in the summer. 'Course, my listening room is only 11x12 so that's a big part of it.
 
I had an Allied 333 that was running a quad of 6BM8 (a penthode/triode) you could fry an egg on it!

I have now a HK A250 with a quad of 6L6GC. The tubes themselves are big and produce a lot of heat, as for the power transformer that gets very hot! After several hours you cannot toutch it for too long!
 
In my last set up, the Manley Stingray put out some heat. Nothing too bad though. It ran (8) EL 84's for drivers. Smaller tubes,but never really noticed the room heating up.
 
If the room is small and mostly enclosed (e.g. many bedrooms) then I can certainly see a tube amp having an affect on the ambient temperature in the room. But if the amp is in a room that is at least medium in size or that is mostly open... then you're not going to notice much if any impact on ambient temperature. This assumes an "average" tube amp. If it's one of the ARC, VTL, or similar amps with 16 power tubes per channel and the size of a small refrigerator... well, you may notice a temperature impact from one or more of those!
 
If the room is small and mostly enclosed (e.g. many bedrooms) then I can certainly see a tube amp having an affect on the ambient temperature in the room. But if the amp is in a room that is at least medium in size or that is mostly open... then you're not going to notice much if any impact on ambient temperature. This assumes an "average" tube amp. If it's one of the ARC, VTL, or similar amps with 16 power tubes per channel and the size of a small refrigerator... well, you may notice a temperature impact from one or more of those!


That is where a good central AC unit with a zone system comes in handy. Thermostats should never be in a bedroom. They should be in a hallway. In our trilevel we have two zones, the upstairs (T-stat in hallway) and the rest of the house (T-stat in den).


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Interesting replies. My room is pretty large at 20x30 so I wouldn't think I'd get much heating effect. Still I'm surprised an amp could make much of a difference even in a room half the size. Maybe I'll turn one of our spare bedrooms into a music room to find out.

Yeah, the wife's going to let that happen. :D

cubdog
 
My Dynaco MKIIIs used to really put my already weak A/C system in my apartment to task on hot days. My Classe' amp also idles pretty hot though and its not tube.
 
I know I guy that had a small study made in an attic with a southern exposure and the tube amp really pushed it over the edge. He got a class D amp for the summer months and went back to an ST 70 when it cooled down.
 
I have 4 working tube amps, Pilot 240, Altec 345A, Radio Shack Stereodyne, and Eico ST40. The Radio Shack runs a little warm but the others give off little heat. The Altec barely breaks a sweat and I have the Pilot (cage off) in a 2.2 cubic foot enclosure on 3 sides and it hardly warms the surrounding air.
 
My Prima Luna Monoblocks, which together light up eight output tubes, four per channel, are excellent winter companions. Placed under a basement window and near my chair, they help to take the chill out of a midwestern January winter. My Audio Research D-76 is similar. With the hand held a foot or so above the amps, it's only a gentle warmth. It's not like any of these amps can substitute for a 1500 watt portable heater.

An honorable mention goes to the McIntosh MC275. I haven't had one in years, but I recall it was rather toasty.
 
I have, in the past, designed HVAC systems for commercial and industrial buildings. While the inclusion of the heat from some tube amps could affect the ability of a minimum sized AC unit to cool a domestic space, it's unlikely. It's also unlikely that you could avoid heating the rest of your house because of the heat put out by your massive power amp. Like most things, it's not as big as you think.
You may think your tubes dissipate a lot of heat but really, even with big tubes, it's not that much.
Before you get a boner and say that the heat dissipated by your system defies the laws of physics, it doesn't and it don't.
A tube that has a a plate dissipation of 60 watts does not emit the same amount of heat as a 60 watt light bulb. This is true because some of the heat goes to the speakers and other parts. While this can produce an aggregate number that is the same, it is not all produced by the tube amp.
 
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I look at how many watts it draws on the back panel. If my tube amp(s) say they draw 200 watts from the wall then it is putting out 200 watts worth of heat. Like a 200 watt light bulb.

If you have a tube amp that draws 400 watts or more then you might have a portable space heater in itself.
 
My Cary SLA-30 got too hot to touch the case. An Octet of EL84's biased for pure class A and in an enclosed metal box with no fan. Hot. Way hot.

- Woody


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