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<blockquote data-quote="John_E_Janowitz" data-source="post: 5507649" data-attributes="member: 550657">I guess the thing to remember is that having power available and using it on a continuous basis are two different things.&nbsp; &nbsp; The new &quot;small&quot; front of house monitors we did for Elite Audio each have a pair of TD12M&#039;s run off 2 channels of a Lab Gruppen 10000Q (1250W per driver) for live sound use.&nbsp; Live sound is a little different as it is not as compressed as recorded music.&nbsp; While you are rarely needing to supply those kind of continuous levels, an uncompressed snare or kick drum can easily clip one of these amplifiers with a 20dB peak.&nbsp; In recorded music there are still transients that can have 6-10dB peaks requiring 4-10X the power to accurately reproduce without compressing the signal.&nbsp; That means at a 400W nominal listening level a peak could require 1600-4400W to reproduce.&nbsp; &nbsp; It is good to have that kind of clean power available.The other thing to look at then is on the driver side.&nbsp; You need the ability to quickly dissipate heat from the coil that is produced during those high power transients.&nbsp; To do this, you need to have a large area to dissipate the heat.&nbsp; Air is a poor conductor of heat so you want the steel top plate and pole as close to the coil as possible.&nbsp; A thicker top plate helps get more heat sinking area close to the outside of the coil.&nbsp; An aluminum former is a good conductor of heat pulls heat from the coil so it can sink it into the pole.&nbsp; On the other hand, a kapton former is an insulator and effectively removes the heat sinking ability on the ID of the coil.&nbsp; A full copper sleeve on the pole like all of our drivers helps to pull heat from the coil quicker.&nbsp; While the steel pole can absorb a lot of heat, it doesn&#039;t do it very quickly.&nbsp; The copper quickly absorbs the heat and then through direct contact to the steel can transfer it much more effectively than the air gap alone. The same premise is used in frying pans with copper on the bottom.&nbsp; A good SQ driver will take into account these thermal issues.In reality you want those same thermal issues to be addressed in an SPL woofer, just for different reasons.&nbsp; For SQ you&#039;re more concerned with the distortion aspects associated with the thermal issues while in SPL you&#039;re concerned about the loss of output.&nbsp; The full copper sleeve also has many benefits in terms of SQ overall.&nbsp; Distortion created by non-linear inductance, flux modulation, etc are also addressed by the copper sleeve.&nbsp;&nbsp; The following was written by Nick McKinney from Lambda Acoustics back in 2001 and revised recently.&nbsp; It talks about the real issues that need to be addressed in low distortion drivers.<a href="http://www.aespeakers.com/Lambda001-1.php" target="_blank">http://www.aespeakers.com/Lambda001-1.php</a>John</blockquote>

[QUOTE="John_E_Janowitz, post: 5507649, member: 550657"] I guess the thing to remember is that having power available and using it on a continuous basis are two different things. The new "small" front of house monitors we did for Elite Audio each have a pair of TD12M's run off 2 channels of a Lab Gruppen 10000Q (1250W per driver) for live sound use. Live sound is a little different as it is not as compressed as recorded music. While you are rarely needing to supply those kind of continuous levels, an uncompressed snare or kick drum can easily clip one of these amplifiers with a 20dB peak. In recorded music there are still transients that can have 6-10dB peaks requiring 4-10X the power to accurately reproduce without compressing the signal. That means at a 400W nominal listening level a peak could require 1600-4400W to reproduce. It is good to have that kind of clean power available. The other thing to look at then is on the driver side. You need the ability to quickly dissipate heat from the coil that is produced during those high power transients. To do this, you need to have a large area to dissipate the heat. Air is a poor conductor of heat so you want the steel top plate and pole as close to the coil as possible. A thicker top plate helps get more heat sinking area close to the outside of the coil. An aluminum former is a good conductor of heat pulls heat from the coil so it can sink it into the pole. On the other hand, a kapton former is an insulator and effectively removes the heat sinking ability on the ID of the coil. A full copper sleeve on the pole like all of our drivers helps to pull heat from the coil quicker. While the steel pole can absorb a lot of heat, it doesn't do it very quickly. The copper quickly absorbs the heat and then through direct contact to the steel can transfer it much more effectively than the air gap alone. The same premise is used in frying pans with copper on the bottom. A good SQ driver will take into account these thermal issues. In reality you want those same thermal issues to be addressed in an SPL woofer, just for different reasons. For SQ you're more concerned with the distortion aspects associated with the thermal issues while in SPL you're concerned about the loss of output. The full copper sleeve also has many benefits in terms of SQ overall. Distortion created by non-linear inductance, flux modulation, etc are also addressed by the copper sleeve. The following was written by Nick McKinney from Lambda Acoustics back in 2001 and revised recently. It talks about the real issues that need to be addressed in low distortion drivers. [URL="http://www.aespeakers.com/Lambda001-1.php"]http://www.aespeakers.com/Lambda001-1.php[/URL] John [/QUOTE]

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