The THIEL SmartSub 1.12 raises a fascinating question: How smart does a subwoofer need to be? For the most part, a subwoofer merely pumps out about an octave of sound, between 40 and 80 Hz. Our hearing isn’t attuned to bass frequencies, so we don’t notice the sonic differences among subwoofers as readily as we notice the differences among speakers. AV receivers have subwoofer equalization circuitry built in to correct for the effects of room acoustics. So why has THIEL--both under its current leadership and under its namesake founder--always strived to make its subwoofers “smart” and marketed them as such?
There’s no denying that the SmartSub 1.12 is one of the smartest subs ever designed. Most impressive is its built-in room correction, a five-band parametric equalizer that uses an included microphone to automatically optimize the sound for your room and your seating position (or for multiple seating positions). If you don’t like the results, you can manually alter each filter’s frequency, boost/cut level, and bandwidth.
The SmartSub 1.12 can be calibrated and controlled through a computer connected via USB or through an iOS/Android smartphone/tablet app. The smartphone or tablet connects wirelessly to the SmartSub 1.12’s built-in Wi-Fi access point.
This subwoofer also offers nice connection options. The back panel has XLR and RCA stereo line inputs and outputs, plus an internal subwoofer crossover. Thus, if your stereo preamp has no built-in crossover (almost none do), you can use the SmartSub 1.12’s crossover, which lets you set the high- and low-pass filters individually in one-decibel increments and also choose from Butterworth or Bessel filters in 12-dB, 24-dB or 36-dB-per-octave slopes, or Linkwitz-Riley filters in 12-dB, 24-dB or 48-dB-per-octave slopes. This means the lows can be filtered out of your main speakers, which will give you smoother bass response and better integration with the subwoofer, and it will improve the main speakers’ power handling.
There are separate delay settings for the high-pass and low-pass filters, adjustable in one-millisecond increments (up to 50 ms), a feature found in all modern AV receivers but few stereo preamps equipped with subwoofer crossovers. Thus, if your sub is three feet farther from you than your main speakers, and you’re using the sub’s crossover, you can time-align them by delaying the main speakers by three milliseconds. This feature should eliminate the need for a phase control, but there’s one on the control panel anyway, and it’s adjustable in one-degree increments to 180 degrees.
A monochromatic, luminescent front-panel display shows all the operating information, including the settings on the EQ. THIEL also includes a small IR remote control that adjusts volume, phase, mute, etc., and lets you flip through the display screens. The remote also scrolls through four different sound modes (Music, Movie, Game, and Night). Plus, THIEL throws in a wireless transmitter that connects to the line outputs of your system so that you don’t have to run a cable to the sub if you don’t want to.
I almost forgot to mention that the SmartSub 1.12 employs a high-excursion 12-inch driver and a 1,250-watt Class D amp. The relatively compact cabinet is available in a gloss black or wood finish.
I placed the SmartSub 1.12 in my room’s “subwoofer sweet spot,” a position just to the left of the right-channel speaker, which is where most subs tend to sound best from my usual listening position. Because I got a very early sample of the subwoofer, the iOS/Android control app wasn’t ready yet, so I used the Windows PC app, which THIEL says has the same functionality. The app is a couple of steps above anything similar that I’ve used, with friendly graphics and an intuitive design that actually made it fun to use and easy to adjust. Following the onscreen prompts, I ran the auto EQ routine, placing the microphone on a photo tripod at my ear height (the mic has a standard ¼-20 mounting socket on the bottom), and running five response sweeps. The display then showed me the in-room measurement, the correction curve it calculated, and the settings it applied on its five parametric filters. As stated before, I could go in and adjust any of those settings.
I connected the subwoofer to my system in three different ways. I tried it in what I think will be its most common setup in two-channel systems, with long Wireworld Eclipse 7 XLR balanced interconnects running from a Classé CP-800 preamp/DAC to the sub’s inputs, and shorter XLRs running from the sub’s outputs to a Classé CA-2300 stereo amp. (This setup works best, with fewer long cables required, if you keep your amp up front between the speakers, as I do.) I also tried using the Classé preamp’s internal subwoofer crossover, with the XLRs going straight to the amp and a long RCA-tipped interconnect running from the preamp’s subwoofer output to the SmartSub 1.12. Then I tried a conventional home theater setup, using my Denon AVR-2809Ci AV receiver and an AudioControl Savoy seven-channel amp, with the receiver’s RCA subwoofer output connected to one of the sub’s RCA inputs.
I used three different sets of speakers: my Revel Performa F206 towers, a visiting pair of Bowers & Wilkins diamond 804 D3 towers (review pending), and a set of small Sunfire home theater speakers, with CRM-2s in the front and CRM-BIPs used for surrounds. I used the subwoofer’s Music mode (which I found measures the flattest) for all music listening, and I switched between the Music and Movie modes for movie listening.
I have two relatively minor complaints about the SmartSub 1.12’s design. First is that the sub itself has no controls at all. You have to control it through the remote, through your smartphone or tablet, or from a connected computer. Second is that the gain could stand to be maybe six decibels higher. There were times when I wanted to push the level of the bass up higher relative to the main speakers, but the sub’s volume was already at maximum.
It seems to me that one of the main reasons why many audiophiles don’t like subwoofers is that, too often, the subwoofer sounds like a separate component in the system, rather than a natural extension of the left and right speakers. This is, of course, unnatural: When you play a double bass, the low fundamental tones and the upper harmonics both come from the same instrument, not from separate places with their own sonic character.
So far, it appears the solution to this problem that audiophiles embrace the least reluctantly is to connect the subwoofer to the speakers or to the output terminals of the amp, as seen in Sumiko and REL subwoofers, and adjusting the subwoofer’s response so that it picks up where the main speakers’ bass response starts to roll off. The upside is that the hookup and setup are simple, and in my experience it’s easy to get a good blend between these subs and the main speakers. The downside of this approach is that the main speakers still have to handle a full load of deep bass, which limits their power handling, increases distortion, and increases the deleterious effects of room acoustics because the main speakers have to be placed for optimum midrange and treble performance, not for optimal bass performance.
Using the SmartSub 1.12’s internal crossover is, in my opinion, the best solution I have found. I used the Sunfire speakers because their limited low-frequency response makes it hard to get them to blend with a subwoofer. But with the SmartSub 1.12’s internal crossover, it was easy. I guessed that using Linkwitz-Riley 24-dB/octave filters at 100 Hz would give me a good blend, and indeed it was a good start. The double bass on “Mistreated but Undefeated Blues” from legendary jazz bassist Ray Brown’s Soular Energy album sounded so much like a real instrument in my room, with a solid stereo image, no booming or distortion, and a generally even response from note to note. That’s a rare result.
I noticed, though, when I played Mötley Crüe’s “Kickstart My Heart” that, while the bass was extremely tight, precise, and well-defined, there did seem to be a little less impact in the upper bass, near the 100-Hz crossover frequency. So I plugged in the computer, sat in my listening chair, and tried some different adjustments, such as bringing the high-pass filter frequency lower, bringing the low-pass filter frequency higher, and using the different filter profiles. I ended up getting the best result by sticking with the Linkwitz-Riley filter profile, pushing the high-pass frequency up to 110 Hz, and going with a shallower, 12-dB/octave response for the high-pass. This gave me an impeccably smooth response; the little Sunfires sounded like a colossal, kick-ass tower speaker system, but with much flatter bass response than non-EQ’d tower speakers could possibly achieve.
Click over to Page Two for more in Performance, as well as Measurements, The Downside, Comparison & Competition, and Conclusion…
“Man, this sounds smooth,” I noted when I played jazz guitarist Steve Khan’s “Casa Loco.” Anthony Jackson’s bass line sounded perfectly even, as I think Khan (one of the best and slickest producers of jazz/rock records) intended. This kind of almost perfectly even, perfectly integrated bass is something I’ve rarely heard, even though it’s what I’ve hoped and tried to achieve with every one of the three zillion subs I’ve reviewed in the last 25 years. And it’s not a result I was able to achieve with the crossovers built into the preamp and my AV receiver, neither of which offers the SmartSub 1.12’s level of adjustability.
I also noticed that, while the SmartSub 1.12 is a sealed design, it doesn’t have the annoying, exaggerated punch that I hear in many sealed designs. The kick drums of Steve Jordan on “Casa Loco” and Tommy Lee on “Kickstart My Heart” were well-defined, but they didn’t sound pumped up, even though in both cases they were pretty heavily compressed in the studio.
I could blabber on and on, giving more musical examples, but I’d be saying the same thing over and over. Whether I used the tiny Sunfires or the much larger Revel and B&W speakers, the SmartSub 1.12 just gave them a lot more kick and extension in the bass without adding any perceptible character of its own. That’s exactly what a subwoofer should do, but so rarely does.
Here are the measurements for the Thiel SmartSub 1.12. (Click on each chart to view it in a larger window.)
The first chart shows the frequency response of the SmartSub with the low-pass filter and the internal EQ deactivated. You can see the effects of the different sound modes here, too. The Music mode is as flat as I’ve measured from a subwoofer, essentially perfectly flat down to 20 Hz and below. (Note that this measurement is taken at a low output level; at high output levels, the bass will drop off, as you can deduce from the CEA-2010 measurements.) The Movie mode introduces a whopping +7.2-dB peak at 68 Hz and rolls off the bass below 30 Hz; clearly the intent here is to maximize output in the “punch” region (i.e., the midbass).
Unfortunately, I messed up my in-room pre-EQ/post-EQ measurements and didn’t realize it until after I’d sent the review sample back to THIEL, so I can’t share those here. However, I did pull a screen shot from the SmartSub 1.12’s Windows app (second chart), which shows the pre-EQ and post-EQ curves that the auto EQ function created, and it also gives you an idea of what the interface looks like.
The CEA-2010 output measurements are fine for a 12-inch subwoofer, although pretty low for a $5,000 subwoofer. In comparison, the larger but $1,000-less-expensive Paradigm 2000SW puts out averages of 122.5 dB at 40 to 63 Hz and 114.4 dB at 20 to 31.5 Hz. With the SmartSub 1.12 in Movie mode, the Paradigm enjoys an output advantage of +4.7 dB from 40 to 63 Hz and +2.8 dB from 20 to 31.5 Hz. With the SmartSub in Music mode, the Paradigm’s advantage is larger: +6.1 and +5.9 dB, respectively. And the 2000SW is beaten (although in most cases not by a lot) by much less expensive models from Power Sound, SVS, and Hsu. As I’ve said in past reviews, if you’re buying purely on the basis of decibels per dollar, the [insert name of high-end sub here] isn’t going to be your first choice.
It appears THIEL put a lot of thought into the SmartSub 1.12’s sound modes. Do you notice how much better the output is in Movie mode and how much more often the sub’s output is governed by the limiter in that mode? This could be nothing more than an artifact of the EQ setting, but the different character of the two modes leads me to believe someone put some effort into this. That’s heartening because sometimes manufacturers get one mode right, then tack on more without much consideration--just so they have more features they can brag about.
I didn’t use the wireless transmitter much, but I did run a frequency response measurement on it just to see how well it works. It doesn’t affect frequency response much, but it does reduce the overall subwoofer level by about seven dB and also introduces 24 ms of additional latency, which is pretty typical for a wireless audio transmitter system. You can probably compensate for this if you’re using an AV receiver or surround processor, but not in a stereo setup.
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 close-miked the woofer and smoothed the result to 1/12th octave. I did CEA-2010A measurements using an Earthworks M30 microphone and M-Audio Mobile Pre USB interface with the CEA-2010 measurement software running on the Wavemetric Igor Pro scientific software package. I took these measurements at two meters peak output. 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.
Audiophiles with solid technical knowledge will have already figured out a theoretical downside to using the SmartSub 1.12’s internal crossover: it digitizes all the signals coming into it. Thiel uses 24/48 analog-to-digital and digital-to-analog stages; so, if you use the sub’s internal crossover, it defeats the purpose of using audio files with high sample rates of 96 or 192 kHz. I couldn’t hear any negative effects--or any effect at all other than the filtering I applied with the crossover. However, I know many audiophiles don’t want to digitize anything, even when the benefits of the digital signal processing are easy to hear and the effects of a well-designed analog/digital/analog chain are at most extremely subtle, and undetectable in any sort of controlled test.
In my opinion, the SmartSub 1.12 is a music sub much more than a movie sub. It sounds absolutely fine with movies; however, with a 12-inch driver in a relatively small enclosure, it can’t muster the low-frequency power and dynamics of larger models. It also loses some of its advantage when it’s forced to rely on the usually simple, relatively inflexible crossovers built into most AV receivers and preamp/processors.
For example, during the scene in U-571 where the sub passes under the destroyer, the SmartSub 1.12 delivered a pretty good amount of low-frequency rumble and no audible distortion, and I liked the extra punch that the Movie mode added to the depth charges exploding a few minutes later. However, it did compress some of the lowest tones in a way that a larger, 15-inch sub probably wouldn’t. In the opening of Edge of Tomorrow, which features a loud 16-Hz tone, the SmartSub 1.12 distorted, but at least it didn’t bottom out or show any signs of dangerous physical distress as some subs have done on this test. In the Saint-Saëns “Organ Symphony” from the Boston Audio Society test CD, the SmartSub 1.12 couldn’t reproduce the deepest pipe organ note (also at 16 Hz) at a significant level, although it did deliver the note’s harmonics clearly and without distortion.
Comparison and Competition
The SmartSub 1.12 will compete mostly with music-oriented subwoofers, such as the $3,999 REL 212 SE, which has two 12-inch drivers powered by a 1,000-watt amp. REL subs tend to be easy to blend with two-channel systems; they rely on an analog connection, so they don’t digitize (or even affect) the signal going into the main speakers. But they can’t achieve the flexibility and precision that the SmartSub 1.12’s DSP-based line-level crossover gave me, and they have no high-pass filtering, so they don’t take any of the load off the main speakers. The REL 212 SE also does not have the EQ functions or sound modes that the SmartSub 1.12 offers. I haven’t reviewed the 212 SE, but my guess is its larger size and dual drivers will allow it to top the SmartSub 1.12’s max output by at least a few dB.
Other competitors include subs from sister companies MartinLogan and Paradigm, both of which cost $3,999 and employ the very effective PBK auto EQ system. (MartinLogan’s BalancedForce 212 offers it as a $299 option.) The BalancedForce 212 has dual 12-inch drivers, each powered by an 850-watt amp, and the Paradigm 2000SW has a 15-inch driver with a 2,000-watt amp. By my measurements, the 2000SW has substantially more output than the SmartSub 1.12, and I expect the BalancedForce 212 would, too. However, neither has high-pass filtering, nor the adjustability of the SmartSub 1.12.
JL Audio’s $4,500 Fathom f113v2 would be another logical competitor, with a 13-inch driver and an amp rated at 3,000 watts RMS short-term; I haven’t measured it, but those specs lead me to believe it might muster a little more muscle than the SmartSub 1.12. It does have auto EQ, but no high-pass filtering nor the SmartSub 1.12’s adjustability.
Of course, the SmartSub 1.12 faces lower-priced competition from subwoofer specialists such as SVS, Power Sound Audio, and Hsu Research. All of those companies offer products that can deliver low-frequency output that’s clearly superior to the SmartSub 1.12’s, at prices that would let you buy two or perhaps even four of their subs for the same cost of a SmartSub 1.12. In particular, SVS’s Ultra and Plus models offer line-level output with a high-pass filter that can be set for seven different frequencies and 12- or 24-dB/octave slopes. They also have two-band manual parametric EQ filters. This level of processing is not as versatile and precise as the SmartSub 1.12’s, but it’s still impressive. Most of these subs are considerably larger and less attractively finished than the SmartSub 1.12.
The SmartSub 1.12 faces the same challenges that other high-end subs do. While the improvements you get by upgrading to more expensive speakers are typically easy to hear, the sonic character of a high-end sub may not be noticeably different from that of a competently designed sub at a much lower price. Where a high-end sub can truly prove its worth, though, is in two areas: its ability to be EQ’d to compensate for room acoustics, and its ability to integrate with a two-channel system. This last feature is especially important because few two-channel preamps accommodate subwoofers at all, and none to my knowledge offer the flexible and capable crossovers necessary to optimize the blend between the subwoofer and the main speakers.
The SmartSub 1.12’s EQ abilities are at least comparable to, and in most cases more flexible than, those of other subs I’ve reviewed. Its ability to blend with main speakers through its internal crossover is the best and most flexible I have seen in a subwoofer. I think, for high-end audio aficionados who value natural sound and probably aren’t that concerned with output and ultra-deep bass extension, the SmartSub 1.12 is a great choice and a way to--at long last--add bass to their systems in a way that doesn’t sacrifice the sound they’ve come to love.
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