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<blockquote data-quote="JohnEJanowitz" data-source="post: 3948136" data-attributes="member: 584636">You can get an idea of how hot the coil is by measuring the DCR.&nbsp;&nbsp; Any time you heat up a coil, either copper or aluminum wire, the DC resistance of the coil is going to go up.&nbsp; How much the coil DCR goes up is directly proportional to how hot it is.&nbsp; Measure the DCR with a multimeter when the woofers are cold.&nbsp;&nbsp; Then when you play it for awhile, measure it again.&nbsp; &nbsp; Let me know the two measurements and I&#039;ll let you know approximately how hot the coil is.&nbsp; I&#039;ll post the formulas if I can find them.&nbsp; Do you know if that is a copper or aluminum coil driver?The coil itself will fail at between 550-600F.&nbsp; TC used the same VC vendor we do and their coils are dipped and baked at 550F and when they cure they can withstand slightly higher temperatures.&nbsp;&nbsp; The trouble is TC always had pretty wide tolerances, meaning more air gap around the coil.&nbsp; Air doesn&#039;t pull heat away very well, and steel doesn&#039;t absorb it well.&nbsp; To really boost the power handling you need a copper or aluminum sleeve on the pole very close to the pole to help pull that heat away.The other thing to realize is that as you heat up the coil, you&#039;re no longer delivering anywhere near the power you think.&nbsp;&nbsp; If you have a 2000W amplifier delivering that power into a 1ohm load, after 5min you can expect the DCR will double or triple and your delivered power will be cut in 1/2 or 1/3.John</blockquote>

[QUOTE="JohnEJanowitz, post: 3948136, member: 584636"] You can get an idea of how hot the coil is by measuring the DCR. Any time you heat up a coil, either copper or aluminum wire, the DC resistance of the coil is going to go up. How much the coil DCR goes up is directly proportional to how hot it is. Measure the DCR with a multimeter when the woofers are cold. Then when you play it for awhile, measure it again. Let me know the two measurements and I'll let you know approximately how hot the coil is. I'll post the formulas if I can find them. Do you know if that is a copper or aluminum coil driver? The coil itself will fail at between 550-600F. TC used the same VC vendor we do and their coils are dipped and baked at 550F and when they cure they can withstand slightly higher temperatures. The trouble is TC always had pretty wide tolerances, meaning more air gap around the coil. Air doesn't pull heat away very well, and steel doesn't absorb it well. To really boost the power handling you need a copper or aluminum sleeve on the pole very close to the pole to help pull that heat away. The other thing to realize is that as you heat up the coil, you're no longer delivering anywhere near the power you think. If you have a 2000W amplifier delivering that power into a 1ohm load, after 5min you can expect the DCR will double or triple and your delivered power will be cut in 1/2 or 1/3. John [/QUOTE]

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