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Thermal Distortion your loudspeaker most likely suffers from it. But do you care?

 Thermal Distortion is much more serious than just a maximum power handling limitation or side effect.TD is overlooked by most manufacturers as there is no easy (low cost) solution and TD is audible and measurable most of the time at most power levels. TD is caused by the conductive metal (aluminum, copper, or silver) voice coil getting hotter when you pass electrical energy through it. The more power you pass through it the hotter the metal gets. The hotter the metal gets the more the electrical resistance increase. The efficiency goes down and you need to ram in more and more power for smaller and smaller increases in SPL. It can be the reason you get fatigued while listening. If you are running massive power you are creating more TD in your transducers. But do you care? And is it a reason some prefer horn-loaded designs or SET-powered systems since they have the least problems with TD? 

johnk

Showing 1 response by lonemountain

lonemountain
475 posts
 

This "thermal compression" issue really impacts those that listen for long periods at higher levels.     In the studio where I go often, this is a MAJOR problem affecting lots of speakers. Active ones and especially passive ones. Cheap drivers or entry level speakers with little cooling can be heated up (long hours of loud music) and become "power compressed".  The effect is distortion but also more than that: its reduced dynamics.  For many tracking engineers, the reduced dynamics of the speaker is THE major issue affecting their work as tracking live sources requires intense dynamic range.  

I don't think there are many consumer customers listening at high levels for hours on end.

Brad  

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