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New Stereo Integrity Mag Pricing Leaked!
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<blockquote data-quote="JohnEJanowitz" data-source="post: 4068905" data-attributes="member: 584636"><p>The rolloff everyone is taking about is simply a function of inductance, not of XBL or any other motor design individually. Any driver with many turns on the coil will have this issue. Some of the most notorious were huge overhung drivers, TC drivers, especially the LMT units which had huge inductance. The old 3HP units for example like our HE15 that TC made for us back in 2002 had HUGE inductance in the 6mH range. You can see the following graph of the near field response measured by Tom Nousaine.</p><p></p><p><img src="http://www.aespeakers.com/pics/power15-nf.gif" alt="" class="fr-fic fr-dii fr-draggable " style="" /></p><p></p><p>You'll see a peak centered about 70hz and then a rolloff beginning above that point. This is a function strictly of the high inductance. In other drivers where inductance was nearly twice as high this peak would be pushed into the 45hz range and above that you begin to see the rolloff. In these cases you are extremely limiting your bandwidth. It's not only the rolloff that causes issues with integration, but the peaking prior to the rolloff. You can EQ out the peak, but the phase and distortion issues caused by the high inductance cannot be corrected.</p><p></p><p>Again, none of this is strictly related to any particular motor design,simply the inductance itself. A near field response of the driver and measured impedance curve should tell you everything you need to know about the high frequency limits of the driver.</p><p></p><p>John</p></blockquote><p></p>
[QUOTE="JohnEJanowitz, post: 4068905, member: 584636"] The rolloff everyone is taking about is simply a function of inductance, not of XBL or any other motor design individually. Any driver with many turns on the coil will have this issue. Some of the most notorious were huge overhung drivers, TC drivers, especially the LMT units which had huge inductance. The old 3HP units for example like our HE15 that TC made for us back in 2002 had HUGE inductance in the 6mH range. You can see the following graph of the near field response measured by Tom Nousaine. [IMG]http://www.aespeakers.com/pics/power15-nf.gif[/IMG] You'll see a peak centered about 70hz and then a rolloff beginning above that point. This is a function strictly of the high inductance. In other drivers where inductance was nearly twice as high this peak would be pushed into the 45hz range and above that you begin to see the rolloff. In these cases you are extremely limiting your bandwidth. It's not only the rolloff that causes issues with integration, but the peaking prior to the rolloff. You can EQ out the peak, but the phase and distortion issues caused by the high inductance cannot be corrected. Again, none of this is strictly related to any particular motor design,simply the inductance itself. A near field response of the driver and measured impedance curve should tell you everything you need to know about the high frequency limits of the driver. John [/QUOTE]
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