Amir, what can you tell us about that dual diaphragm compression driver? From what I've been able to find online, it sounds like it uses two identical diaphragms, one behind the other, driven by separate voice coils, each of which receives the same signal. This is certainly a novel concept for a compression driver in my experience; I think BMS's dual diaphragms are concentric - that is, the smaller round high frequency diaphragm is in the middle of a larger donut-shaped mid frequency diaphragm. It almost sounds like the JBL configuration is a quasi-isobaric, wherein the the inner diaphragm relieves the backpressure on the back of the front diaphragm. If I'm mistaken about the configuration of the new JBL compression driver, please correct me.
And, what is it about this new configuration that enables it to offer improved performance vs conventional compression drivers?
I realize you may not have the answer to these questions, but I hope you don't mind my curiosity.
On another subject, I stand up and applaud JBL's attention to and success in minimizing the spectral discrepancy between the on- and off-axis sound. That is arguably the most important thing to get right in a high-end active system, because radiation pattern is one thing that DSP cannot do much about.
Very nice juggling of the (remarkably few) tradeoffs as well. There's a slight dip in the off-axis energy centered on roughly 700 Hz, and that's not a bad place at all for a dip. That's the "gank" region, one of two regions where imo a dip isn't necessarily a bad thing.
I'm under the impression that JBL is using an alloy in their voice coils whose resistance stays essentially constant as its temperature changes, which helps to alleviate a primay cause of thermal compression and thermal modulation. If I recall correctly, Earl Geddes applied for a patent on such an alloy years ago, but eventually abandoned it. Anyway, if that's what JBL is doing here, again that's a very intelligent upgrade.
Any comments you can pass along about these or any other technical aspects, I'm all ears.
Thanks!