Can temperature fluctuations affect audio gear?

I think the OP of this thread can get away with running his gear in a 85 degree room,as long as the gear has good ventilation.At 85 degrees,he'll probably have a fan making a nice breeze up there.His owners manual would be the best guide.I don't think it will go into a thermal runaway,type of condition.Humidity can cause slower heat transfer too.The worst conditions I've seen for gear is,component stacking,or enclosed case gear.Gear done this way in a 70 degree room,is worse off than the OP of this threads condition,IMO.This can cause bad heat build up.I don't have the thermodynamics education,just some common sense,I hope.

Heat does indeed kill electronics, or at least reduce mtbf. However, if the equipment is well designed from a thermal management/heat sinking standpoint, and if parts such as electrolytic capacitors whose mtbf may be particularly heat sensitive are well chosen, the effects of heat will not become significant until temperatures are reached that are much higher than might be expected.

Those are very big "if's," of course. And I would not expect that small manufacturers of high end equipment will always or even usually have thermal design specialists on staff, not to mention that providing conservative design margins will tend to increase the cost of the product.

But to provide some perspective, commercial grade integrated circuits are most commonly rated for ambient operating temperatures of 0 to 70 degC, that being conditional in the case of higher powered devices on heat sinking provisions that maintain reasonable junction temperatures. 70 degC = 158 degF! Specifications for integrated circuits used in military avionics usually require an ambient operating temperature range of -55 to +125 degC. 125 degC = 257 degF! (Although keep in mind that "ambient" for each device means the nearby temperature inside the case of the equipment, not the external air temperature).

Devices that consume large amounts of power, such as computer cpu's, usually have considerably lower ambient temperature ratings than those numbers, but they are still higher than one might expect. Current Intel quad-core desktop cpu's have a TDP (thermal design power) of 130 watts. It boggles my mind that so much power can be dissipated in such a small package, even with the special heat sink and fan that is required. Consider how hot a 100W light bulb gets, the bulb being considerably larger than a cpu chip!

Addressing Magfan's point about the fact that computer enthusiasts (I am one one of them) pursue exotic cooling solutions, the reason for that is not to extend life but to optimize overclocking ability (running the cpu at faster than its rated speed, which enthusiast-oriented motherboards make possible). Faster speed = higher power consumption and higher internal temperatures, and higher internal temperatures will limit the maximum speed at which the cpu can be operated without crashes.

Overclocked cpu's utilizing good aftermarket cooling devices typically run reliably for many years with internal junction temperatures in the area of 40 degC (104 degF) when idle, and 75 degC (167 degF) to 90 degC (194 degF) when performing intensive processing.

Best regards,
-- Al

12-05-10: Magfan
It would seem that as the ambient temperature and temperature of the electronics got closer and closer, the amount of HEAT transferred would get less and less. It maybe that BigBucks is right, but I don't see it. The constant delta above ambient may work but I just see stuff getting hotter faster than the room it's in....especially if the room is externally heated...sunlight, hot day...etc. At some point, the junction temp of an output device would be nearing limits and be unable to dump enough heat.....thru all forms of shedding...radiation, conduction, convection....(others?) But would that be at a constant delta from ambient?
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From above:
"It would seem that as the ambient temperature and temperature of the electronics got closer and closer"

How does that happen? If the room (equipment) is getting hotter, the components are getting hotter at the same rate (given that everything was in equilibrium in the first place.

The equipment dissipates a given amount of power (at a specific operating load). The power is dissipated as heat through the componet body, thru the board, then out thru the heat sinks. That thermal 'resistance' to heat flow is constant. So, a given heat flow (power dissipation) to ambient thru a fixed resistance must yield a constant delta T at the component end. That's why the component junction temp is a constant above ambient.

And I 'know' this because I work on aerospace electronics where we do thermal analyses all the time. I guess all these years we must've been wrong about increasing component temps by the ambient temp delta ;)

Al, computer cooling, certainly a 'side issue' here is related to hifi. The point being that 'heat kills'. Enough statistical data exists to support this.
I had a Motherboard which had an automatic overclock feature when the CPU was pushed. I kept it on the most conservative setting and ran one of the Zalman Cu/Al 'mushroom' shaped heat sinks with the fan on 'full'. I chose a conservative CPU and never pushed it. I never saw my 2.4gig CPU go above about 2.6 I kept the dust bunnies cleaned and the all the cooler fins de-linted.
Point is valid that 'heat kills'.

Processing temperatures for Silicon devices run from about 1150c for some of the Junction Drives down to very low temps like 200c or less, used for 'sinter' or 'anneal' processes...usually right at, or near the 'end of the line'. Nothing goes above about 425c after 'metalization' which is usually an aluminum alloy and deposited somewhere mid-line. I am not current on what is used in State of the Art CPUs. They may have gone to copper or some other metal. Very thing / narrow aluminum has some problems with reliability and electromigration.

The 'statistics' to which Paperw8 also refers to are valid. They are well understood and proven. That they are statistics means you are dealing with populations.....large numbers of a given object some of which will crap out immediately and others which will last.....seemingly forever. The 'take away' is that Al is also correct: MTBF is the most visible metric applied to this stuff. The object of manufacturing quality is to produce product in the middle of the spec. All 'excursions' are suspect.
Semiconductor plants, called 'fabs' spend a bundle on 'rel labs'....Reliability. Here they torture what they make in an 'accelerated' lifetime. Indeed, before a new product or process is released to production, parts must go thru what is called a '1000 hour burn-in'. Too many failures or parametric shifts during the test are grounds to deny the 'go ahead' for volume production. What went wrong? The innocent are usually than punished.

I worked at a company that had a 'Hi/Lo' group. Bad lots were investigated....what went wrong? Especially GOOD lots got the same treatment....what went right? Go Figger.

Now, if you go for the 'weakest link' line of thought, buying mil-spec stuff for part of your design and cheap-o commodity chips for other parts doesn't make sense. This is why good equipment is not only well designed...but well executed, too. One could probably build a Bryston Copy for a fraction the cost of the real thing but out of cheaper parts and NO warranty! It wouldn't surprise me to learn that companies like Bryston had 'thermal budget' folks on hand. Engineers to calculate and verify type and amount of heat sinking. Even those IR imagers to look for 'hot spots'. All sorts of cool, hi-tech lab gear.

Mil Spec parts are not necessarily different from those you can buy. I say necessarily because electrically they may be the same and even made in the same fab. The difference is that NO rework is allowed, so if a production 'lot' has a problem, it is immediately either scrapped or degraded to 'consumer'. Other rules apply and the factory audits are BRUTAL. A factory must EARN the right to build Mil-Spec parts and be so certified. Than periodically audited. The taxpayer picks up the bill. You'd use parts like that, too, if a repair call took you 200 miles into space.

Having no formal education on the subject,let me give my two cents anyway.Use F with these examples.

Semiconductor@90f mounted to heatsink @ 30f.High transfer

Semiconductor@90f mounted to heatsink @ 50f Good transfer

Semiconductor@90f mounted to haetsink @ 90f Any transfer?

Semiconductor@90f mounted to heatsink @ 91f Any transfer?
Or the reverse, absorption?