Heat


Hi All,
I have a friend who was telling me how he keeps a fan turned on, facing towards his amplifier, to keep it from getting too hot. I told him that it doesn't matter because the only heat that will affect his amplifier comes from internally. I'm now wondering if I could be wrong. So I'm wondering, if a stereo is in an attic during the summer and it's being played to the point of getting hot, will the temperature in the attic effect the amplifier?
goofyfoot
You are right about heat being generated internally. From there it flows into other things such as the heat sinks by a process of conduction. When you put a spoon in a cup of hot tea and the handle starts to get warm this is conduction. So the amp heats the heat sinks and this takes some of the internal heat away. But what if the outside temperature is higher? Then less heat flows out. That's conduction.

Now on the outside some of the heat simply radiates away. If you've ever seen infra-red images that is from this radiation. Some heat also warms the air. Warm air rises being replaced by fresh cool air. This is convection. This is why heat sinks are vertical, to maximize convection. 

Convection can be increased with a cooling fan. The more air the more convection and the greater the cooling. Always depending of course on the temperature of the air. A heat gun is after all blowing heated air. 

So yes your amp will get hot and run hotter in a hot attic. Most all SS amps have thermal cutoff for heat protection. It is best to avoid this. If it does happen however simply let it cool and resume. Then look for a better cooler location for your amp.
Thanks millercarbon, that's a great explanation!
Heat is the enemy of audio equipment. The lower and more constant you can keep equipment, the longer it usually lasts. Failures primarily occur from thermal cycling. I'm not saying to keep your equipment on all the time and I don't like the noise a fan makes. But when you listen at moderately loud to loud volumes, a fan will help extend the life. I use Rotron whisper fans.
Ambient temperature will effect how much heat you amplifier can dissipate. The warmer the ambient temperature the less it will be able to. Airflow will greatly enhance an amplifiers ability to dissipate heat.

I use 12" computer cooling fans on my preamp - on both the power supply unit and the line level unit. I've mounted them in butcher blocks which I have laid flat on top of both the chassis'. The blocks are cut to the same dimensions as the pre-amp chassis' and the fans are orientated to extract air from the pre amp units. Both units are now cool to the touch no matter what the ambient temperature is, where before they were noticeably warm.

I cannot say if it will extend the life of the amp or the tubes, but I'm sure it doesn't hurt. It helps to dampen any chassis vibration and I definitely think the noise floor is a little lower. 
Post removed 
So a fan doesn't hurt anything, this is probably common sense. And this is basically what I told my friend. My thought would be that if the amp had an internal power supply, that this would increase heat inside the unit. My friend has a Rega amp so it doesn't have visible heat sinks. The heat sinks on my amp however probably weigh 40 pounds on each side and my power supply is external. However, my amp is in my attic so I don't play it much in during summer. 
Just remember your removing the heat, not cooling the unit. By cooling the "WAY" it transfers heat, (the heat sink fins) it PULLS the heat out of the enclosure quicker, just like MC said.. By using internal fans and conduction. One is drawing heat out and the other is replacing the air inside the case.. Neither will work when the ambient is HIGH. It can actually work the other way with the heat sinks. They exchange heat, which ever is the lower, outside or inside..

A block of ICE. Fix you right up.. Maybe set the amp on the ice, not the ice on the amp.. :-)

Must be an ugly one to hide in the attic? ay?  I had a girlfriend like that.. I just used a bag when I got drunk, then double bag when I'd sober up..

Boy could she..... Dance.. :-)

Regards
oldhvymec, yeah, the difference between a dog and a fox is about two beers.
If you have ever tried to cool a hot food liquid in a spoon (in order to taste it) inhaling the steam/heat is much more effective/faster than blowing on it.

Because of this in the few instances where I've used fans to cool tube gear I implemented the fans to draw heat away from the unit (VS blowing air on the unit).

DeKay
Motron looks like AC Infinity with less features for more money.
I use two computer fans underneath 845 SET amp, tremendous current and heat from these transmitter tubes. Don't bother with my other tube amps and pre.
Then if the room is cooler, the heat s being drawn through the heat sinks with greater efficiency?
Then if the room is cooler, the heat s being drawn through the heat sinks with greater efficiency?

Yes. Cold air consumes more energy (heat) from the cooling than warmer air can. 

Two factors come into play. 1.) The colder the air, the more heat it can absorb before it reaches a temperature where it will no longer absorb heat from the sinks. 2.)The faster the rate you can replace the air that has already absorbed heat from the sinks with cold (room temperature) air, the faster the rate that heat can be transferred away from your amp.
Theoretical, or actual amp in an attic? Summer attic temperatures are like this

https://www.youtube.com/watch?v=EhZba-P7R18

Pushing hot air at a hot thing ain’t gonna do much. Attic exhaust fans can avoid extreme temperatures, but not enough IMO.

A box with small personal ac unit can work, however, power on/off, settings, and importantly condensation needs to be dealt with.

Some floor standing room units have ducts to vents like a clothes dryer, that would work if that could be worked, again, an enclosure to retain the cooler/block the hotter air would be wise. I used one of them to cool the V Berth in a boat in Florida I inherited (thankfully sold) found one with self evaporation, pvc pipe for heat exhaust.
Very simply, the operating temperature of electrical equipment is X deg F above whatever is the ambient w/o forced cooling such as a fan.  If X deg F is say 25F, and the ambient temperature is 75F, the internal operating temp is then 25F + 75F = 100F.  If the attic reaches 95F, the equipment operating temp increases to 25F + 95F = 120F.  In reality,  X deg F above whatever is the ambient is somewhat variable for the static condition, but for the range we are generally talking about its relatively constant. 

As @millercarbon has detailed, forced air can increase the heat transfer lowering the equipment internal operating temp.  But for forced air to lower the equipment operating temp (to remove heat) there has to be a temperature difference - the ambient air temp has to be less than the equipment internal operating temp (or the external heat sinks).

The easiest example for what happens at elevated operating temps is to look at a capacitor.  The average capacitor in home audio equipment is rated for an operating temp of 85C (185F) for 1000-hrs.  For every 10C(18F) less that it operates, the service life doubles.  So, operate at 75C, the life is ~2000hrs.  Operate at 65C, the life is ~4000hrs, and so-on.  But, operate at 95C and the life drops in half to ~500hrs.  

Quick examples:  If in a 25C(77F) room & an equipment operating temp of 40C (104F), the service life of the 85C/1000-hr capacitor is ~22,000-hrs.  In an attic at 35C (95F), and an equipment internal operating temp of 50C (122F), the service life of the  85C/1000-hr capacitor is now only ~11,000-hrs.

Some of the better audio capacitors such as  Mundorf are rated 105C while Teflon capacitors are generally rated 125C. Industrial power capacitors may be rated 85C/10,000-hrs - they are designed for 30-yrs continuous service.  
antinn, thank you. I believe all of my capacitors are Vishay and that’s as much as I know. Anyway, I’m thinking that I’m safe in the attic as long as I stay away from playing time during the hot season. Because of the hardwood floors, it is very dry up there which is also good for my electrostatic speakers and in the fall and winter, it stays very cool.
Dear friends : ""  Heat is the enemy of audio equipment. "" and I can add: operation out of the limits of the source of electrical power.

Now, every decent amplifier designer/manufacturer takes in count those both parameter in his design overall/main targets and his calculations on the design takes in count both parameters.

So if the amplifier is well designed no one needs any " crazy fan " even in the attic due that not only because the well designed unit but because that good engineering designer already designed his unit with a thermal protection and to electrical protection too.

Look, I own two Levinson 20.6 monobloks and in my country ( México. ) people have air conditioners only in those country places where temperature goes as high 50° C but in zones where as my place that does not happens we in reality do'nt use even with temperatures at 35°C.

In the winter and in the cooler days that normally never gone below 0°C the pure Class A 20.6 puts as warmer ( heatsinks and all the amplifier external metal surfaces. ) as in summer. Difference is that during the winter the time to get hot is a little longer.

Yes, those amps does not puts warmer but hot really hot, you can't touch its external heatsinks even the face plate and the handles are warm enough.

Guess what? no matters what the amps never switched to its thermal protection circuit. The 20.6 has not internal fan and its electrolithics filtering caps are rated at 95°C by Sprega that today is member of Vishat group and the Wima caps used in the circuits are rated at 105°C.

The design is all about, period.

Those amps came around 1987-1989 and never failed in any way:

https://worldradiohistory.com/Archive-All-Audio/Archive-Audio/80s/Audio-1987-08.pdf

Regards and enjoy the MUSIC NOT DISTORTIONS,
R.

A fan can add  dirt, noise or grunge to the electric line and make the sound bad. Make sure it is not plugged into any sockets or lines that the system is on.
Everything will overheat and blow up attic is worst place for a stereo.
ebm, except in the winter.

Thermal cycling kills electronics over time.

fiesta75, according to the manufacturer of my amp,

he suggests allowing the amp to sit at low volume

for a bit prior to normal play. Do you think that this will

help with thermal cycling at all?

Is thermal cycling a new Olympic event?

OP, it could help but not sure how much. Thermal cycling is used for accellerated aging of electrical components. Can be both powered or unpowered. A very high percentage of electronic failures are caused by mechanical fatigue.