±3.0 dB from 18 to 152 Hz
Crossover low-pass roll-off
(1M peak) (2M RMS)
40-63 Hz avg 123.2 dB 114.2 dB
63 Hz 123.3 dB L 114.3 dB L
50 Hz 124.7 dB L 115.7 dB L
40 Hz 121.4 dB L 112.4 dB L
20-31.5 Hz avg 114.6 dB 105.6 dB
31.5 Hz 118.6 dB L 109.6 dB L
25 Hz 113.8 dB 104.8 dB
20 Hz 108.7 dB 99.7 dB
The chart here shows the frequency response of the R-115SW with the crossover set to the maximum frequency, or LFE mode (blue trace) and to the 80-Hz position (green trace).
The only weird thing about the R-115SW's frequency response is that big rise, peaking at 70 Hz. Note that it disappears when the crossover is engaged, and you get an almost perfectly flat response with a -3dB point at 80 Hz--exactly what you're supposed to get. So, while the sub doesn't measure flat without a crossover (which would never be the case), it should deliver a fairly flat response with one. If your receiver has an adjustable crossover slope, I'd recommend setting it to 3rd-order (-18dB/octave) response, which is closest to the response of the sub's internal crossover.
The CEA-2010A results for the R-115SW are pretty impressive, in the neighborhood of what I've measured from some competing but typically larger subs. For example, the Hsu Research VTF-15H Mk2 delivers an average of 126.9 dB in the low bass (40-63 Hz) region and 119.9 dB in the ultra-low bass (20-31.5 Hz) range. My guess is you wouldn't notice the Hsu's +3.6dB improvement in the 40-63 Hz region because few people crank their system up loud enough to hear that. But if you're really pushing the sub with ultra-low-frequency material, I would suspect from the measurement alone that the Hsu's +5.3dB advantage from 20-31.5 Hz might make a significant difference. (As you can read in the review, my ears confirmed this.) Note that the R-115SW hits its limiter at every frequency from 31.5 to 63 Hz, which tells you the distortion will be relatively low at these frequencies. Maybe that's why I got such a great sense of tightness and punch from this sub.
Here's how I did the measurements. I measured frequency response using an Audiomatica Clio FW 10 audio analyzer with the MIC-01 measurement microphone. I did a ground-plane measurement with the microphone placed on the ground two meters from the sub, and the results smoothed to 1/6th octave.
I did CEA-2010A measurements using an Earthworks M30 measurement microphone, an M-Audio Mobile Pre USB interface and the CEA-2010 measurement software running on the Wavemetric Igor Pro scientific software package. I took these measurements at two meters peak output, then scaled them up to one-meter equivalent per CEA-2010A reporting requirements. The two sets of measurements I have presented here--CEA-2010A and traditional method--are functionally identical, but the traditional measurement employed by most audio websites and many manufacturers reports results at two-meter RMS equivalent, which is -9dB lower than CEA-2010A. An L next to the result indicates that the output was dictated by the subwoofer's internal circuitry (i.e., limiter), and not by exceeding the CEA-2010A distortion thresholds. Averages are calculated in pascals.
While the R-115SW offers impressive bottom-octave bass power, it can't quite match the floor-shaking muscle of the most powerful 15-inch subs I've tested...although it does come pretty close. For example, the 16-Hz tones on the recording of the Saint-Säens Organ Symphony from the Boston Audio Society Test CD-1 didn't shake my floor as much as they do with the Hsu VTF-15H Mk2 or the Power Sound Audio XV15se, although the R-115SW did reproduce the tones fairly cleanly. I also didn't get as much ultra-deep rumble from the engines of the submarine and destroyer in chapter 14 ("Face to Face") of U-571.
I also felt I was able to get just a touch more bass definition from the Sumiko S.9 and the Hsu VTF-15H Mk2. With the R-115SW, I heard all the notes clearly, but I didn't get quite as much sense of "growl" from electric bass. That difference is subtle, though, and dependent on how well your sub blends with your speakers, which is in turn dependent on the crossover in your receiver or preamp/processor--and I'm probably hyper-sensitive to it because I play bass.
Comparison and Competition
The obvious competitors for the $899 R-115SW are the Hsu VTF-15H Mk 2 and the Power Sound Audio XV15se, both 15-inch subs in the same price range. The Hsu costs $1,008 including shipping; the Power Sound costs $899 with free shipping. Both of these competitors deliver a few dB more output than the R-115SW. I didn't notice this difference at the higher frequencies, where the R-115SW seemed like it was trying to collapse my chest at times. However, as noted above, I did hear it in the lower frequencies below 40 Hz. But the Klipsch does have that appealing punch, possibly to a greater degree than the others.
The Hsu allows extensive tuning, with sealed, one-port, and two-port modes plus a Q knob that controls the resonance bandwidth (translation: tightness vs. looseness) of the sub. Neither the Klipsch nor the Power Sound model offers this, although of course an aftermarket EQ could be added to either.
Note that the Hsu VTF-15H Mk2 is 20 percent larger than the Klipsch R-115SW, but the R-115SW is eight percent larger than the Power Sound XV15se. The Klipsch is, in my opinion, nicer-looking than either competitor, but that's not saying a lot.
I was starting to think that mainstream speaker companies had no business in today's subwoofer business because they can't deliver the kind of value and performance that some of the Internet-only guys can. The R-115SW proves that notion wrong. It's competitive with practically any subwoofer on the market, yet it costs under $1,000. It does give up a little bit in power compared with its toughest competitors, but few home theater enthusiasts are likely to push their systems hard enough to discover this. And I think many audiophiles will be drawn to the R-115SW's great sense of power and punch.
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