When you try the JL (I'm quite sure you'll be happy with it), just make absolutely sure that you have it located a minimum of 2ft closer to your listening position than your main speakers!!! There is latency in the subwoofer circuitry, which will delay the sub's signal by at least a few milliseconds. This means that if you add delay (adjust the phase on the JL) the best you can hope for is to be a full wavelength behind the main speaker's bass output, making perfect integration impossible. And any sub with digital circuitry is receiving an analog signal from the amp, converting it to digital (A-D latency), then manipulating it via digital crossover, digital EQ, etc. (more latency), then converting it back to analog (D-A latency) before the signal gets to the driver. The amount of latency varies by manufacturer and design, but it's there. So don't line the sub up with the mains!!!
A perfect subwoofer integration with a high-end stereo requires that (A) the stereo be setup perfectly without the sub, and (B) the sub is setup to roll into the system at the point where the mains give up. This is easier to do if you have sealed main speakers. A bit harder with stats and dipole speakers. And much harder with ported speakers, which usually have surprisingly good anechoic measurements and surprisingly bad in-room response - they often run out of gas around 60Hz and come back with a vengeance around 40HZ (in room), making perfect sub integration difficult. Fortunately, the very low frequencies are more felt than heard. so if you do it right you can get a nice response curve and a visceral gut punch when it's called for.
The only way to not localize a sub, unless it's crossed over hard below 50Hz, is to make sure it's timed perfectly to coincide with the mains. Anything else will sound like a pair of speakers and a sub. If the timing is perfect, it will be glorious!
BTW, I've had lots of audiophiles with Wilsons, Focals, Magenpans, Soundlabs, Vandersteens, etc. tell me that a sub in a 2-channel system is a travesty. And then I measure their system and show them that those high-price speakers aren't putting out ANY accurate information below about 40Hz (again, in-room response). So they're not hearing anything lower than the lowest note on a Fender Bass. No pipe organ bass. No low synth bass. None of the beautiful bass harmonics that the strike on a tympani makes.
If you don't have the fundamentals at <20-40Hz you also don't have any of the rich harmonics that should naturally cascade all the way up into the upper bass ranges. To miss this information is to miss much magic.
A properly integrated subwoofer is a game-changer that you can never un-hear. And an improperly integrated subwoofer will mangle an otherwise adequate system. Do it right, or don't do it!
A perfect subwoofer integration with a high-end stereo requires that (A) the stereo be setup perfectly without the sub, and (B) the sub is setup to roll into the system at the point where the mains give up. This is easier to do if you have sealed main speakers. A bit harder with stats and dipole speakers. And much harder with ported speakers, which usually have surprisingly good anechoic measurements and surprisingly bad in-room response - they often run out of gas around 60Hz and come back with a vengeance around 40HZ (in room), making perfect sub integration difficult. Fortunately, the very low frequencies are more felt than heard. so if you do it right you can get a nice response curve and a visceral gut punch when it's called for.
The only way to not localize a sub, unless it's crossed over hard below 50Hz, is to make sure it's timed perfectly to coincide with the mains. Anything else will sound like a pair of speakers and a sub. If the timing is perfect, it will be glorious!
BTW, I've had lots of audiophiles with Wilsons, Focals, Magenpans, Soundlabs, Vandersteens, etc. tell me that a sub in a 2-channel system is a travesty. And then I measure their system and show them that those high-price speakers aren't putting out ANY accurate information below about 40Hz (again, in-room response). So they're not hearing anything lower than the lowest note on a Fender Bass. No pipe organ bass. No low synth bass. None of the beautiful bass harmonics that the strike on a tympani makes.
If you don't have the fundamentals at <20-40Hz you also don't have any of the rich harmonics that should naturally cascade all the way up into the upper bass ranges. To miss this information is to miss much magic.
A properly integrated subwoofer is a game-changer that you can never un-hear. And an improperly integrated subwoofer will mangle an otherwise adequate system. Do it right, or don't do it!