Revel Home Theater (SGHT Review) Page 7
Is the Revel the best subwoofer system I have yet had in my home theater? Well, almost. There is a significant downside to its performance. The SUB-15/LE-1 appears to operate at the edge of its capabilities; too much is being asked of it. While it can produce alarming bass levels, it doesn't do so without complaint. When it overloads, it produces anything from a slight motorboat sound to a distinct rattle. Careful listening pinned these noises to driver distress, not cabinet or room vibrations (which were also evident; more in a moment). This is not always audible when the full system is up and running; it is often masked by other sounds above the bass range. But I heard it often enough that I began listening to the SUB-15 by itself for a more in-depth analysis.
Two SUB-15s increase the overload margin slightly, but not by as much as I expected: less than the 6dB or so of increased gain from coupling two side-by-side subwoofers. However, they still overload when reproducing the most demanding material at or slightly below THX reference levels.
Even a single Revel subwoofer can produce a more terrifying bottom end than the 18" Velodyne on many soundtracks, but the Revel can be driven into overload, something I have found difficult or impossible to do with the Velodyne in months of use. You pay a price for this: Above a certain input level, particularly at very low frequencies, the Velodyne simply refuses to put out more bass. The Revel keeps cranking out thedBs, which is both its strength and its weakness. It puts out simply awesome sound on such bass-heavy action films as Independence Day and Jurassic Park, but it does let you know when you push it too hard.
In an attempt to produce some objective results, I measured the maximum sound pressure levels that the Velodyne and a single Revel subwoofer would put out before showing distress. I was looking for driver overloading, not cabinet problems, but the Velodyne's cabinet had an annoying buzz that began well before overloading. The Revel's cabinet actually fared worse: At high levels, it buzzed all over the place. This rattling was apparently due to the Revel's wood trim, grille, and spiked feet. They had all been tightened down securely, but they still wanted to sing along. To eliminate these sounds and prevent misleading results, I unfastened everything that is screwed onto the SUB-15 and placed the unadorned cabinet on my padded carpet.
To make a long story short, the Velodyne produced 3-7dB more output than the Revel in the 20-40Hz region before overloading (6-7dB more at 20 and 25Hz). Actually, the Velodyne never showed signs of overloading at any frequency but one (a slight buzz at 20Hz); its maximum level was simply the level at which its dynamic limiter set in.
The Revel's overloading got progressively worse beyond the onset level, but it continued to produce increasing output even while rattling away. I didn't continue this abuse for more than a second or two for fear of damaging the driver. At some point, I'm sure the SUB-15 would either rip itself apart or run into severe amplifier clipping. While the actual nearfield output of both subwoofers was very high at the overload point, it was seldom much over 100dB SPL as measured at the listening position (which is affected by room resonances). This is loud, but not outrageous.