Art Welter wrote on Wed, 07 April 2010 18:37 |
David,
The 4018LF has an Xmax of 7.9 mm. The B&C 18TBX100 has an Xmax of 10 mm. According to your sim, they both have exceeded Xmax with 2kW.
Art Welter
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I'm going to pipe up in Art's defense here, as I think he is correct in supporting the driver in question.
It should also be mentioned that the change in voice temperature is not likely being factored into these simulations, which are based on small-signal T/S parameters.
Raise the voice coil temperature by 150C, thereby changing Re appreciably, and the needed tuning for good performance will have changed dramatically. Qe has effectively increased, and driver excursion will also increase.
The WinISD simulations presented are not going to give a realistic portrayal of the driver performance at high input voltages. It will also result in the production of a subwoofer box that will not be properly tuned when driven the way most professional loudspeakers are driven.
The JBL differential drive speakers have quite good thermal performance compared to more conventional designs, if you look at the thermal time constants that JBL publishes for their conventional drivers compared to differential drivers. Even if the driver Xmax was the same as the other drivers mentioned above, the JBL likely still has a thermal performance advantage.