NHT Evolution T6 Tower surround speaker system Page 2
The external amps and crossover in the T6 system provide a lot of flexibility, but at a cost. The system is complex, and all those extra chassis and cables are a nuisance—but probably more to a reviewer (who has to reconfigure everything several times a year!) than to the average user. Provided you have room in your equipment rack for the X1 and one or two A1s, and you don't change your system around a lot, the extra hardware should give you no more headaches, once it's set up, than more common, internally powered subwoofers.
The two Evolution T6 Towers were positioned on both sides of my 80-inch-wide projection screen and slightly forward of it. This put them about five feet out from the front wall, firing down the long dimension of my 15.5 x 26 x 8-foot home theater. The M6 center-channel was placed just below the screen on a low stand, positioned horizontally and tilted up slightly to aim it toward the main seating area. The M6 surrounds, attached to NHT's optional, matching P6 pedestal stands ($400/pair), were located about 8 feet behind the listening seats and slightly out from the room's back wall.
When you assemble the T6 Towers, be careful to first decide whether you want to position the B6 subs with their drivers facing in or out, as this will affect how you position the top-mounted M6s. I faced the B6s outward. I had no large piece of furniture, such as a big-screen TV, in the center where it might have interfered with the sub's output had the drivers to be positioned facing in. But I did have a free-hanging projection screen and wanted to avoid any chance that the air movement from four 12-inch woofers might cause it to flutter, even slightly. A very unlikely possibility, perhaps, but had it happened, I'd have had to fully reconfigure the left and right front speakers, swapping not only the entire towers left to right but the M6 modules as well, due to their asymmetrical nature.
There are several ways to connect the B6 subwoofers, all of them described in depth in the owner's manual. You can use the crossovers and bass management in your receiver or surround processor and connect its subwoofer output to the X1/A1 (Method 1). Or you can run the left- and right-channel preamp and subwoofer outputs on your receiver or processor to the X1 and let the latter perform most of the crossover and bass-management functions (Methods 2 and 3).
NHT recommends Method 3 for systems configured as mine (separate surround processor and main-channel amplifier), but I chose Method 1 instead. This has the disadvantage of not allowing for stereo bass (Methods 2 and 3 do, if you use two A1 amps), nor does it make use of the X1's crossover controls. But the crossover controls in my surround processor are flexible, and I haven't found stereo bass to be particularly advantageous, as long as the crossover to the subwoofer is kept low enough. While my surround processor offers other options, I used 80Hz, a frequency widely available in surround processors and receivers. Most important, however, Method 1 allowed me to directly and instantly compare the low bass of the B6 subwoofers with that of my current reference sub, the Revel B15, by means of a line-level switch and careful level-matching between the B15 and the B6s.
The setup diagrams in the manual show the left and right speakers firing straight ahead, with no toe-in. I prefer to toe-in the front left and right speakers in a home-theater setup because this provides the best coverage of the main seating area for more than one listener. But toeing-in the T6s can be tricky because of their asymmetrical radiation pattern. I recommend determining the best angle by feeding pink noise to the right speaker, then toeing it in until the timbre change at the right seating position becomes obvious. Don't be fooled by the initial loss of extreme high-frequency sparkle as you rotate the speaker the first few degrees from straight ahead. (If you are in a seat off to the side with the speaker aimed straight ahead, you may well be nearly on-axis, where most speakers are slightly directional in the highs.) Instead, listen for a slight deadening of the sound in the low treble/presence region. When you reach that point, turn the speaker back a few degrees toward head-on, until you can barely hear a change in balance as you move from the center to the side of the seating area. Use the same toe-in for the T6 on the left side and you're there.
NHT has designed the M6 to sound best with its grille in place: I listened this way throughout the evaluation. But the plastic grille frames on the B6 subwoofers rattled badly on high-powered soundtracks (not with music), so I removed them.
I began my listening in stereo with the left and right T6s only. Sitting centered in the "sweet spot," I was immediately taken by the speakers' well-balanced, uncolored sound. I always listen first for any sign of unnatural midrange coloration, particularly on vocals. I heard nothing amiss: no nasality or boxiness symptomatic of uneven response, no boomy or woofy qualities indicating mid- or upper-bass unevenness, and no excessive fizz or sibilance characteristic of peaks in the mid treble.
The NHTs just sounded right on nearly everything I played. Dead Can Dance's Into the Labyrinth (4AD 45384-2) was up-front but not pushy or bright. The recording was made in a reverberant church, and sounded exactly as you'd expect: big, open, and loaded with ambience. Ry Cooder's superb (and remarkably varied) soundtrack CD of the music from Geronimo: An American Legend (Columbia CK 57760) has always been exceptional, but on the T6s I discovered it all over again. It had excellent detail and convincing depth. The recording is a little bright and certainly not sweet, but it's loaded with unique instruments and effects. You can sense the studio manipulation that is clearly present on the recording. The NHTs didn't exaggerate such flaws, but they didn't hide them, either. At one point, during a particularly quiet passage, something can be heard dropping to the studio floor; it sounds as if it's about 50 feet away. The NHTs clearly reproduced not only the impact itself, but the studio's reverberation tail as well.