I am pretty upset reading this review. What was JBL thinking when designing this speaker?
A 1.5kHz crossover (or is it 1.7kHz like initially published?) is way too high for this woofer, and the result was to be expected.
The 1200Fe (or whatever variation this speaker is using) is a great woofer, one of the best for this size, but it was never intended to play this high, and that is clearly visible in the tolerance boundaries for the frequency test procedure found in its EDS:
http://www.audioheritage.org/vbullet...1&d=1216860198
A +/- 3dB unit-to-unit variation is allowed above 1356Hz, which is pretty normal given the random breakups that can occur with such a cone, but this is clearly no place for a crossover. This means that anomalies found with the unit tested here might not be there with another unit, or might be worse. Anything can happen exactly where everything should be under tight control.
And even if that tolerance issue was solved (might be the purpose of this particular variation, but that would imply pushing breakups modes further up: good luck doing that with a paper cone of this size), there is no way it would play nice with a compression driver up there.
I used to have a pair of 4425, employing an - arguably not as good - 12" woofer crossing to a compression driver at 1.2kHz, and the transition was very audible. They solved the problem with the 4429 going as low as 800 or 900Hz with the 1200Fe, pairing it with a small metal dome compression driver and a wide directivity horn to match directivity.
Now we are back to a 1.5kHz crossover, Eon territories with premium drivers...
I get it that the D2415K cannot play low, but then they should have used another compression driver for the task and crossover no higher than 1kHz (and preferably lower).
The 175Nd in the 4429 had no issue there, as did the poor 2416H in the 4425 at 1200Hz, and those were clearly not premium drivers at the time.
The new dual ring radiators are pretty good when it comes to high SPL (as seen in the Vertec and other JBL PA speakers) and HF, but it is notorious that they are struggling at low frequencies (eg the D2430K, which shows increased distortion under 2kHz compared to a classic 4" diaphragm compression driver), so this is no wonder that half the radiating area for the D2415K compared to the D2430K would require such a high crossover frequency. JBL does not do dome compression drivers anymore, and even had to use Radian drivers in the new Everest, but these ring radiators are also probably much cheaper to produce compared to metal dome drivers, so they should have just used the D2430K in the 4349, and call it a day.
This is shameful, how can they market this in the synthesis lineup with such compromises in the design??
I do have a pair of 1200Fe and D2430K here, but I would clearly never intend to make them play together.
These speakers probably sound good overall, they better do with the drivers at hand, but the result should be textbook perfect. Anything less than that is an insult to all the efforts and years of evolution that went into the components and technologies used here.
If only Greg Timbers was still in command there, I bet this would have turned out quite differently...
Well... sorry for the rant
I'd like to say that I feel better now, but frankly I don't...