Zaph|Audio
Frosty The Speaker!
Effect of temperature on a woofer
Introduction
I had a set of woofers I was going to put in my car. This is Wisconsin, with wicked cold winters and blazing hot summers. So I thought, hmmm, I think I'll run some temperature tests to see how these woofers can handle the elements. The woofer in question is a Vifa P17WG-19 6.5" poly cone with a rubber surround and a phase plug.
Getting my goal test temperatures proved to be a little tricky. But basically, after messing with various appliance settings, the speakers were temperature treated using the refrigerator, freezer and oven. And of course, the 70 degree was room temperature. It took a while to get the speaker to each goal temperature, and once I started testing I had to work super fast before room temperature started to affect measurements.
Frequency Response - 0 thru 110 degrees F
Impedance - 110 degrees F
Impedance - 70 degrees F
Impedance - 40 degrees F
Impedance - 0 degrees F
Theile-Small Parameters - 110 degrees F
Theile-Small Parameters - 70 degrees F
Theile-Small Parameters - 40 degrees F
Note: SE got confused trying to get T/S parameters at 0 degrees. It's hard to do when there is no impedance peak!
Summary
Not surprisingly, Fs and Vas were the parameters that drastically changed as the temperature changed. At zero degrees, the speaker practically had no resonance and output below 200Hz was non-existent. The top ends of the response curves changed only slightly, with the breakup and damping shifting around a bit.
The bottom line: Car audio is a difficult proposition unless you live in a place where the climate does not change much. Even with the car's climate controls working to keep the driver warm/cool, car door speakers are close enough to the outside of the car that they are still affected by outside air.
This loss of climate control is one of the many reasons why I lost interest in car audio. There are so many tradeoffs required to reproduce music in a car that it will never be even remotely close to the high standards of home system. I still love music in a car, but I accept the default system in much the same way a teenager accepts the sound of an MP3 player to fill the void of empty silence.
Page done by John "Zaph" Krutke © 2005
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