Brent has been a professional audio journalist since 1989, and has reviewed thousands of audio products over the years. He has served as editor-in-chief of Home Theater and Home Entertainment magazines, contributing technical editor for Sound & Vision magazine, senior editor of Video magazine, and reviews editor of Windows Sources magazine, and he also worked as marketing director for Dolby Laboratories. He's now on staff at Wirecutter.
The Sunfire XTEQ12 brings back a fond memory for me: seeing the press release for the first Sunfire subwoofer, back in 1995. It pictured Sunfire founder Bob Carver, holding his new miniature subwoofer and standing outside his nondescript company headquarters, with power lines and pine trees in the background. That original Sunfire True Subwoofer--a combination of a beefed-up driver and passive radiator, Carver's cool-running Tracking Downconverter amplifier, and a bass-boost circuit to compensate for the sub's tiny enclosure--changed the audio industry. It was widely copied, and its influence can be seen in practically every subwoofer sold today.
The new XTEQ Series subwoofers barely look any different from the original, even though Carver is long gone from the company. The top-of-the-line, $2,000 XTEQ12 features a 12-inch driver, a 12-inch passive radiator, and a Tracking Downconverter amp rated at 3,000 watts. The line also includes 8- and 10-inch models.
The big difference between the XTEQ Series and the original Sunfire subs is an auto EQ function. Plug the included test microphone into a jack on the back of the sub, put the microphone where your head will be when you're in your favorite listening chair, and hit the start button on the back of the sub. The sub then automatically steps through four tones (35, 49, 64, and 84 Hz) and uses the signal from the test microphone to EQ itself automatically, thus optimizing its response for your room acoustics. You can also EQ the sub manually, although this function is limited; all you can do is bump any of the frequencies up by +6 dB. Either way, a tiny switch on the back panel lets you turn the EQ on and off after it's set.
Of course, auto EQ is built into most AV receivers. However, if you don't like the results of your receiver's auto EQ, or if you're using the XTEQ12 in a stereo system with no auto EQ, this feature could come in handy.
The XTEQ12 is a nicely finished cube that's fairly heavy for its size. On the bottom, it has four Anti-Walking Tread Design Feet, which are intended to keep the sub from scooting around on tile or wood floors as it vibrates.
The XTEQ12 offers some unusual and welcome hookup options. You can do the usual line-level run (via RCA or XLR cable) from your receiver or preamp/processor. Or you can feed line-level signals via RCA cables from a stereo preamp to the sub, then run those signals straight out to your amp--and, if you like, employ the XTEQ12's switchable 85-Hz high-pass filter to cut the bass out of the signal that feeds your main speakers. This feature makes it easy to use the XTEQ12 in a stereo system with a pair of mini-speakers. With most subs and stereo systems, you'd have to run the mini-speakers full-range, in which case you're almost certain to get bass distortion and likely to get less life out of your speakers.
I used the XTEQ12 with a Klipsch Reference system based around the RP-280FA towers. I used two sets of electronics: a Denon AVR-2809Ci receiver connected to an AudioControl Savoy multichannel amp and a Pioneer Elite SC-89 equipped with Dolby Atmos. I used a subwoofer crossover point of 80 Hz, so the sub would have to handle most of the bass on its own, without help from the tower speakers' woofers.
I was surprised to notice a heat sink on the bottom of the sub. Past Sunfire subs I've reviewed didn't have this, and I was under the impression that the Tracking Downconverter amp (which is essentially a Class G/H design) runs cool enough that it doesn't need an external heat sink. This heat sink has tiny fins that are about a quarter-inch high, and it's recessed into the bottom of the chassis, so it gets little airflow. The sink gets quite hot and sits close enough to the ground that the fins left an impression in my low shag carpet. The heat didn't damage my carpet; but, if I had an expensive carpet, I'd be worried.
By the way, it's a good thing those Anti-Walking Tread Design Feet are there, because this subwoofer does a lot of shaking back and forth when it's playing deep bass notes.
The first thing I had to do was test the auto EQ and see if I should use it during my review. These systems don't always work as advertised; one manufacturer actually recommended that I not use his sub's auto EQ, which was developed not by his company but by whichever company manufactured the sub's amplifier. So I played a couple of tunes with melodic bass lines--Steely Dan's "Aja" and the live version of James Taylor's "Shower the People"--to see how the sub performed in my listening room's "subwoofer sweet spot" without the EQ. Then I ran the EQ, which takes just a couple of minutes, rechecked the subwoofer's level in the receiver, and listened again.
The difference was pretty obvious. The auto EQ didn't radically change the sound, but without it, some notes in those tunes' bass lines were a lot quieter than others. Given the excellence of the bass players on these tunes, and the amount of processing and compression used in the mixes, I think it's safe to say these lines are supposed to sound almost perfectly even. With the auto EQ in, every note in the bass lines came in at about the same level, and the lines sounded smoother and more melodic as a result. I left the auto EQ turned on for most of the rest of my evaluation, switching it off only briefly on a couple of movie scenes where I wondered if the EQ was reducing the output a bit.
In fact, tunes such as these (and Toto's timeworn classic "Rosanna") are where the XTEQ12 shines. Once you hear a well-produced, slick musical performance like these through a sub that's been EQed for your room, it's hard to go back to a sub that's running without EQ. The groove of the tune is better because the bass doesn't drop out on certain notes, and you can get a better sense of the tune's harmony, too.
I could hear this advantage even more on Holly Cole's "Train Song" from the Temptation CD. The tune starts with deep notes from an upright bass. Through the XTEQ12 without auto EQ, it sounded fine, about like what I'm used to hearing. With the auto EQ, the notes were more even, and I also seemed to get a better sense of the "growl" in the upper harmonics of the notes.
You won't notice this improvement in every tune; when I played the intro to "Detour Ahead" from disc three of the Bill Evans Trio's The Complete Village Vanguard Recordings 1961, bassist Scott LaFaro's opening notes sounded hardly any different with auto EQ. Why? Because a subwoofer crossed over at 80 Hz is handling only the fundamental tones of the bottom 13 or so notes of a standard bass. Your main speakers handle all the harmonics, plus the fundamentals of all the middle and upper notes.
This even response in the second octave of bass (40 to 80 Hz) did nice things for movie soundtracks, too. When I played the scene from the Interstellar Blu-ray disc where the ship first enters the wormhole, the intense midbass vibrations came through beautifully, giving me a convincing sense that I was inside a metal vehicle on the verge of being shaken apart. Later scenes, such as the one where one of the spaceships is struck by colossal waves, also gave me a powerful sense of the bass vibrations in the soundtrack.
Click over to Page Two for The Downside, Measurements, Comparison & Competition, and Conclusion...
The downside of the XTEQ12 is literally the downside: the bass region below 40 Hz. While I got good output in all the punches, kicks, and explosions in movie soundtracks, I didn't get much of that powerful, room-pressurizing low-frequency energy that the biggest and best subwoofers deliver.
For example, in the scene in U-571 where the titular submarine dives under a destroyer and you hear the engine noises of the sub and the ship, I didn't experience the intense, floor-shaking deep bass that the best subwoofers can reproduce. The deck cannon shot and resulting explosion in the scene had reasonable punch and impact, as did the depth charges that follow, but the "thrill ride" part of the experience was mostly missing. ("Good!" I can almost hear some audiophiles shouting.)
I felt the same way during the Attack of the Clones clip. The XTEQ12 was able to entertain me, but not to scare me; it didn't have enough deep-bass power to really suck me into the action. I'm being picky here, but most of the $1,000-and-over subwoofers I test do have this capability. If you play movie soundtracks at quieter levels, you might never notice this...but then you probably don't need a $2,000 subwoofer, either.
As I always do during subwoofer tests, I played the recording of the Saint-Saëns Organ Symphony from the Boston Audio Society Test CD-1. This recording features pipe organ notes going down to 16 Hz. With a top-notch subwoofer, this track will scare you because you feel your entire house vibrating and probably hear things in adjacent rooms rattling, much as you do in a mild earthquake. With the XTEQ12, not only did I not get this effect, but when I cranked it up, the sub actually produced a couple of false tones that obscured the original notes--the result of harmonic distortion, which creates false tones that aren't in the source recording. Later measurements confirmed a false third harmonic at high levels with the deepest bass tones, essentially adding a tone an octave and a fifth higher. Of course, very little music and movies has much content at such deep frequencies, but enthusiasts rightly expect that a top-of-the-line, expensive subwoofer will play practically any material at high levels without gross distortion. In fact, SVS's PB-1000--a larger but, at $499, much less expensive ported model with a 10-inch driver--handled the deep tones in the "Organ Symphony" with more authority and lower distortion.
±3.0 dB from 43 to 91 Hz
±5.0 dB from 24 to 110 Hz
Crossover low-pass roll-off
The top chart shows the frequency response of the XTEQ12 with the crossover set to the maximum frequency, or bypass mode (blue trace), and to the 12:00 position, or roughly 80 Hz (green trace).
I had to open up the measurement spec on the XTEQ12 to ±5 dB. You can see that it clearly has ample response down into the 25-Hz region, but a peak at 70 Hz throws off the ±3dB spec. Yes, the auto EQ could help fix this, but I think it would be a better strategy to get the sub's response flat before EQ; if your room has a resonance at 70 Hz, the auto EQ might not have enough range to tame it because of the sub's 70-Hz response peak. The 24-Hz deep bass extension figure in my results represents a good estimation of what you'll get in a normal room, especially if you're using a receiver and you engage the receiver's auto EQ function.
The bottom chart shows the XTEQ12's response measured at my seating position before (green trace) and after (orange trace) auto EQ. As you can see, the effects of the auto EQ were limited but still significant. In my listening position (and throughout much of the room), my room has a broad peak at about 40 Hz, which the EQ flattened out nicely. It also slightly reduced a mild peak at 84 Hz, but it didn't do anything to flatten the peak at 63 Hz. I'd say this performance is actually above-average for a relatively simple subwoofer auto EQ system, although I've had better results with systems such as Velodyne's Digital Drive and Paradigm's PBK.
The CEA-2010A results shown here are for a second test sample that Sunfire supplied after seeing my results with the first sample. It measures better than the original sample: The original averaged 115.0/101.0 dB, the second sample averaged 116.2/105.4 dB (these averages are for 40-63 Hz and 20-31.5 Hz, respectively). However, neither set of numbers is impressive for a $2,000 subwoofer, even one this small. For example, the SVS SB-2000, a $699 sealed-box subwoofer that's almost exactly the same size as the XTEQ12, averages 117.8/107.4 dB. The SVS PB-1000, a $499 ported sub with a 10-inch driver and 300-watt amp, averages 118.2/111.6 dB. Velodyne's $899 Wi-Q12, a 12-inch, 225-watt ported sub that has an auto EQ function similar to the XTEQ12's but also adds wireless capability and remote control, averages 116.5/103.1 dB.
It's worth noting that, at 63 and 50 Hz, the subwoofer's distortion was relatively low; total harmonic distortion (THD, including in this case the second through fifth distortion harmonics) was 9.6 and 5.5 percent, respectively, with the second sample. Typically, I might see numbers more like 15 to 25 percent THD here. That probably sounds like a lot because we're all used to seeing THD quoted for amplifiers, but for a sub even 10 percent THD is usually just barely audible. So the limiter keeps the XTEQ12's distortion low and probably prolongs the life of the driver and passive radiator, but it may be preventing the sub from delivering the dynamic peaks that a less conservatively designed product can achieve.
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, with the sub's auto EQ turned off. I did a close-miked measurement with the microphone placed about a quarter inch from the woofer and the passive radiator, then summed the responses. (I often don't close-mike subs, but in this case I did because both radiating surfaces are the same size and thus require no scaling of the curves before summing.) Given the somewhat unusual frequency response result, I checked the measurement by doing another measurement in a ground-plane environment, outdoors at one meter with an Earthworks M30 measurement microphone, smoothed to 1/6th octave, and got almost identical results.
I did CEA-2010A measurements using the Earthworks M30 mic, 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. The sub's auto EQ was switched off.
Because of the XTEQ12's unusual performance, I performed two rounds of measurements on the original sample and a new round of CEA-2010 measurements on the second sample. I also did some more measurements, using TrueRTA software and the Earthworks mic to measure peak output during passages of U-571 and the "Organ Symphony."
Comparison and Competition
The XTEQ12, being relatively small at roughly 14 inches on each side, doesn't compete with the big monster subs from companies such as Hsu Research, PowerSound Audio, and SVS. It's best compared with smaller "lifestyle" subs, preferably ones that have some sort of auto EQ function.
For example, Paradigm's $1,100 Monitor Sub 12 has a 12-inch driver and a 900-watt amp, and it's about the same size as the XTEQ12. For $100 extra, Paradigm can supply the Perfect Bass Kit (PBK), which in my experience is a more sophisticated and effective auto EQ system than the one used in the XTEQ12. The downside of the Monitor Sub 12 is only that it's ugly; the "pretty" version, the Prestige 1000SW, costs the breathtaking sum of $2,999. Unfortunately, I don't recall having done output measurements on either one. However, I seriously doubt that any decent sub more than $500 can't match or, more likely, exceed the XTEQ12's output.
If you really want auto EQ (and aren't using a receiver with it built in), any subwoofer can be combined with an add-on auto EQ, such as the $269 DSPeaker Anti-Mode 8033Cinema. Another alternative is to buy two less-expensive subwoofers and put them in the corners of the room. Even without auto EQ, two subs will automatically smooth out some of the negative effects of room acoustics on the bass response, and you'll get the beneficial effects over a larger part of the room, so the sound is optimum not just for you, but for everyone.
There are things I like about the XTEQ12, including its auto EQ, its built-in high-pass filter for satellite speakers, and its small size. However, it doesn't deliver any more output than many models at much lower prices do, and subs with similar or even superior feature packages are available for much less. Yes, a Sunfire subwoofer is a classic, but one has to expect that a $2,000 subwoofer with a 12-inch driver and a 3,000-watt amp will deliver powerful deep bass. That challenge is simply missed with this product.
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