[michiganjfrog]

Originally Posted by HubbleMart";p=&quot

As a speaker transducer / driver designer, I work with materials & their properties.
Exposing a plastic such as PP to temperatures way below freezing will & do cause hardening or brittleness of the material at room temperatures. (a study of the material's behaviour over temperatures will tell you so). This in turn will harshen the sound above the cone's break-up point. (the break-up is more harsh due to lower damping). This is one of the reasons why some of the best speakers do not use plastic based cones, as they tend to sound different over time.

Secondly, a large driver, with a 3" voice coil will on an average have a coil with the wire length exceeding 50 meters. As a part of the curing process of some of the high-end coils, we heat them to a temperature above 500F while ensuring that the coil is in a fixture and not allowed to change shape.
Besides, the metal (copper / aluminum) in the coil will again heat up quickly the next time you feed real power into the speaker, thus neutralizing any positive effect the freezing might have had on it.

As I said before - this stands more true for the larger high power drivers & those using plastic / PP parts.

Come to think of it, the drivers I froze were probably paper cones, but with rubber surrounds. I dont know the size of the voice coil, but apart from the Philips tweeters, it did include a large woofer, perhaps 12" diam. I have some speakers with poly cones that I was "one day" going to freeze, but having read this, I'm even more curious to go ahead with that. I believe I may have read about some people freezing their drivers with poly cones, no reports of faults, but I can't recall for sure at the moment if they were indeed that material. We're not talking cryogenic temperatures here either... I dont know that most domestic freezers go much below 0, at least not Farenheit.