The Gotham itself comes equipped with a low-pass crossover with two different, user-selectable slopes—a second-order (12dB/octave) Butterworth filter and (my preference) a fourth-order (24dB/octave) Linkwitz-Riley filter. (In addition to its steepness—down 100dB per decade [ten times the crossover frequency]—the Linkwitz-Riley filter has the estimable advantage of 0dB gain at the crossover hinge point. Given that you’re likely to cross over somewhere in the 50–80Hz region, not adding energy precisely where rooms do the most damage is a better idea.)
In addition to its low-pass filters, the Gotham has calibrated controls for subwoofer gain, phase (0–360°), crossover hinge point (30Hz–130Hz), and E.L.F. (extreme low frequency) trim. (This last cuts and/or boosts frequencies below 20Hz to compensate for excessive ultra-low-bass “room gain” in small-to-medium-sized spaces.) The only thing the Gotham doesn’t have—and, rather paradoxically, the e110 does—is a high-pass filter.
I would imagine this was not so much an oversight as a tacit acknowledgement that woofers this big, powerful, and deep-reaching are most likely to be used in elaborate home-theater systems, where “bass-management” (low-pass and high-) will be handled by surround-sound/home-theater electronics. However, that does rather leave two-channel listeners in the lurch. In my experience, running any subwoofer/satellite system with a low-pass-only crossover scotches one of the advantages of using a sub, which is to transfer some of the heavy lifting from the woofer or mid/woofer in the main speaker to the woofer in the sub. (In addition, and despite propaganda to the contrary, running the main speaker full-range often makes achieving a seamless blend between it and the sub a good deal more difficult, as there is bound to be a region of considerable overlap between the two bass drivers.)
Happily, JL Audio has an answer to this problem, as well, its new CR-1 outboard crossover.
Now, to be honest, in the past I was no more a fan of outboard subwoofer crossovers than I was of, uh, outboard subwoofers. The very idea of sticking another piece of electronics—generally of considerably less than high-end transparency—between your preamp and your amp was and is anathema to old-timers like me. So when JL Audio’s Brett Hanes, the resident engineering genius behind many of JL’s subwoofing breakthroughs (and a genuinely amiable and modest young man), showed up at my digs with the CR-1 I was less than enthused.
I should’ve known better, given my previous experience with Brett’s work for JL.
While I can’t say that the CR-1 is completely invisible sonically, it is unquestionably far more transparent than any active subwoofer crossover, built-in or external, that I’ve tried—and over the decades I’ve tried a few. In Brett’s words, the CR-1 was “engineered for audiophiles by audiophiles,” its design based on years of calibrating subwoofed systems for picky high-enders.
What the CR-1 offers in the way of fine adjustments is precisely what JL Audio’s subwoofer experts have determined matters most—nothing more and nothing less. Built into it are three essential tools, meant to work alongside, replace, or refine those already included in the Gotham itself.