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? Max Temperature's you can operat the speakers in ?


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What is the maximum temperature, (Hot/Cold)(long or short term) that you can use the Heritage line before you kill them? I am referring to small parts like the delicate diaphragms and voice coils in drivers. Could they handle moderate fluctuation in temperature change. What is the max temperature you can operating the speakers in before you start damaging the diaphragms and woofer?

4-Cornwalls

2- soon to be ALK Heresys!

Thanks Guys!

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I've never seen any specs on this for any home system. It may be that auto speakers have specs and are designed for a wide range of temperatures. Obviously people get in their cars in the dead of an Alaskan winter or the heat of a Mexican summer, and hit the radio. I've not heard of that causing a failure.

The most common failure of a voice coil is caused by heat. However it arises from too much electrical power being fed to them. I'll take a guess that this requires the coil getting up to the temperature of molten copper.

You might also know that the coils are wound onto a former which may be made of cardboard and coated with something like enamel. In the big power woofers, there is a lot of design effort to use materials (plastics or aluminum) which are heat resistant.

If I had to guess, I'd say the softening points are well above 200 degrees F.

There is a law of thermodynamics which says the rate of heat transfer is proportional to the differences in temperature. On one hand, that means that hot things cool more rapidly, or don't get hot, if there is a cool reservoir (sp?) nearby, to sink off the heat energy. (On the other hand, it means your finger at 98.7 degrees absorbs energy more quickly from a hot iron, than a cool one.)

The issue is then. If you have a 200 degree coil near failure, the difference between it and 100 degree and 130 degree air is a change of 15 percent. 30/200. Therefore, being in a hot room and a very very hot room is not so much looking at rate of heat transfer. But naturally this really depends, in a mid or tweeter, on air trapped in the driver and radiation to the magnet structure, etc.

It may be that some of the elastic materials in the surround gets stiff when cold. So performance might change a bit.

The electrical components in the crossover should be very tolerant to heat. For example, the oil bath capacitors in your Cornwall (nice picture) are of the type used in tube equipment. The insides of such equipment gets very warm by todays standards. The coils and transformers should be okay too. Again, these were used in tube equipment.

Overall, I wouldn't worry about ambient temperature. If a human can get by with a parka, or shorts and a tee, there should be no problem.

Gil

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