JBL 4367 = Sleep Denervation

@james633 --

Congrats on your JBL 4367’s. I find them to be an impressive design from a relatively compact size factor, and agree that stands should be included. There’s something about the good old "15 inch woofer/mid and a horn" combo that has a timeless appeal as a very versatile, coherent and powerful sounding system. Perhaps a core element of this is the crossover region of these designs typically placed somewhere between 500-800Hz, and what it offers with a point source above in a large frequency span as well as an untarnished "power region" (say, 150-400Hz) below via a large coned driver where no crossover point is placed. Having a large radiation area here lends a fullness and vitality to this region that smaller woofers and midrange drivers (and often in multi-way designs with a XO point in the power region) simply cannot replicate.

I agree with poster @mijostyn’s good advice on high-passing your JBL’s for subs augmentation, though do it right - i.e.: also be mindful of the type of subs chosen, but as an outset you have a pair of JL Audio subs to experiment with, so see what you can harness it all into, and whether it coheres fittingly into a whole. Ultimately I’d go higher efficiency sub designs like the ones meant to be paired with the M2’s, as I suspect they’ll blend more seamlessly with type of woofer used in your 4367’s. This is not trivial, as I have tried out different constellations of higher eff. mains with lower eff. subs, and personally I find they just don’t mesh properly - for a variety of reasons.

As it is they’re still very capable used full-range (the only way I’ve heard them), and given their moderately high sensitivity and large air radiation area the doppler phase shift phenomena mayn’t be as pronounced here. Certainly using dual high eff. 15" woofers up to ~600Hz per channel in the main speakers (like I do), full-range, they have to be spanked pretty hard for the cones to move visibly, and when high-passed at ~85Hz to high eff. subs there’s zilch movement even at war volume levels.

@jheppe815 --

+1

@james633 wrote:

there is almost no information comparing these very large subs other than home theater applications and I don’t trust those opinions as their wants are far different from mine. It is hard to say how something like the SUB18 compare to the JTR captivators which also measures well.

Looking at the data of those two sub options (i.e.: JBL SUB18 vs. JTR Captivator RS1), it’s clear the lower tuned JTR is digging deeper with the same diameter driver from a smaller enclosure volume, and per Hofmann’s Iron Law that translates into lower efficiency. With the JBL’s rated at 92dB sensitivity, somewhere between moderate to high eff., it means the JTR’s are down there in the 85-87dB sensitivity region (certainly not higher). The thing is you don’t merely compensate with more power for a same-same scenario wrt. perceived bass imprinting between the two subs; even playing similar SPL’s they don’t sound the same, contrary to what measurements may indicate in the central bass area where most musical information resides. My assumption would be for the JBL sub to be somewhat more tuneful and textured in its bass response compared to the JTR, hereby being the better match to your 4367’s. Coming down to it the SUB18’s don’t go that much deeper than your mains (half an octave perhaps), but the real takeaway is high-passing the 4367’s in the 80Hz vicinity and have those SUB18’s (two of them, no less) take over from here. That is, relieve your 4367’s of central to low bass for cleaner and more dynamic mids and upper bass, and let the subs do what they do best here - THAT will make a difference. While the JTR’s dig deeper to make for some infrasonic effects with movies I’d wager the JBL subs are the better match with movies as well, even giving up sub 20Hz reproduction, being they likely provide better central bass slam and "bite" while being of the same "sonic cloth" as the main speaker woofers. This is not trivial, and something many overlook. Remember, integration is key.