There are multiple benefits to adding one or more subwoofers to a stereo, surround system, or even a soundbar. With a good sub, you can improve the low-frequency extension of most systems and relieve amplifiers of the burden of reproducing those frequencies. Typically, it's a win-win for your speakers and amps. However, proper integration is the key to getting the most out of any sub, and that can prove tricky if you don't have EQ at your disposal.
The ELAC Debut S12EQ Sub.
Adding a subwoofer to an audio system is a challenge because rooms have a lot of influence on sound, especially in the bass region. Fortunately, proper placement and a bit of EQ can tame an unruly response curve.
ELAC's Debut S12EQ ($700) is a 12" sub that includes a function called Auto-EQ, which works in conjunction with an Android or iOS device to correct for the usual room-related peaks and nulls. With minimal effort, it can provide a flat in-room response for the listener.
The S12EQ is part of ELAC's Debut line of speakers—designed by Andrew Jones—that aims to offer high performance at affordable prices. The company sent me the S12EQ along with a pair of its Debut B6 bookshelf speakers. I had requested the sub, mainly because I feared the bookshelf speakers would lack impactful bass. It turned out I was wrong; the B6s are surprisingly potent down low. Therefore, I decided to split that system into two reviews, the one you are reading here and my recent review of the Debut B6s
The S12EQ is a powerful, versatile 12" sub. The enclosure is a perfect 17" cube that weighs 49 pounds. A 500-watt (RMS) amplifier provides ample power to the front-firing active driver, while a down-firing 12" passive radiator augments low-frequency output. ELAC specifies the frequency response of the sub from 28 to 150 Hz.
The app-based DSP found in the S12EQ sets it apart from other similarly priced subwoofers I've seen and heard. Gone are all external controls you typically find—there are no knobs or switches in sight. On the back of the sub, there's nothing but an RCA input and a reset switch.
ELAC's Sub Control app connects to the S12EQ via Bluetooth, so you don't need a Wi-Fi network to get it up and running. However, you do need an iOS or Android device (phone or tablet) to set it up. I successfully connected to the sub using an iPhone, an Android phone, and an Android tablet.
An outstanding feature of the aptly named S12EQ is its Auto-EQ function. It's a quick and easy 2-step calibration that smooths out a lumpy bass-response curve. While most AVRs and pre/pros offer EQ as part of a room-correction system, many devices with subwoofer outputs—such as soundbars, self-powered speakers, and 2-channel preamps—do not.
In addition to Auto-EQ, the S12EQ provides a flexible 1-band parametric EQ that lets you dial in the exact bass response you want. Also, the app provides a volume control, phase control, delay control, and a variable lowpass filter—all very useful tools for subwoofer integration.
The S12EQ offers several listening modes: Normal, Music, Cinema, and Night. Normal mode aims to deliver the sub's "designed response" to the listener—in other words, it aims for flat. Music mode adds a small boost to the bass at just under 40 Hz, emulating the effect of room gain for people who want some extra oomph down low. Movie mode adds a boost around 55 Hz to enhance the visceral thumps found in so many soundtracks. Finally, Night mode automatically turns down the sub's volume and adds limiting, so as not to disturb sleeping family members or the neighbors.
Setting up the S12EQ was a cinch. I placed the sub against the side wall, ran Auto-EQ, and was good to go on my first try. Seriously. The software was incredibly effective, yielding a smooth response curve with minimal effort.
Auto-EQ is a two-step process. First, you hold your phone or tablet within a foot of the sub’s front-facing driver while it plays test tones. The app takes nearfield measurements at various bass frequencies, which takes less than a minute.
The second step involves taking another quick set of readings from the listening position. As it runs the routine, the app creates an EQ curve to compensate for any dips and peaks it finds. You get to see exactly what the app is doing; it displays both a graph and numerical measurements as it goes about its business.
Auto-EQ starts by generating a profile, then it creates a correction curve for the listening position.
I used Room EQ Wizard (REW) and a UMIK-1 USB mic to validate Auto-EQ's settings, and soon I grew to trust it. I experimented with placing the sub in various locations, and I used three different devices to perform the Auto-EQ calibrations. The result was a very consistent calibration, regardless of which device I used for the task or where I put the sub.
For surround content including games and movies, I used my Pioneer Elite SC-85 AVR to perform the processing and provide power to the main speakers. The AVR liked the S12EQ's Auto-EQ settings so much that when I ran the AVR's MCACC room correction, it saw no need to add any EQ of its own. For speakers, I used a KEF R-series Atmos surround system that you can read about here
Thanks to its Auto-EQ capability, the S12EQ also proved to be a great match for soundbars and powered-speaker systems that offer a subwoofer output but lack room correction capability. In fact, I used the sub in my review of the MartinLogan Motion Vision X
soundbar. Setup consisted of running the calibration routine, telling the soundbar that a sub was connected, and adjusting the output level to taste.
Wow! That's the word that best describes the S12EQ. It handily surpassed my optimistic expectations when it came to the quality and quantity of bass it produced.
The S12EQ excels at rendering textured, nuanced bass. However, in terms of raw output and low-frequency extension, it does not dig as deep as three similarly priced subs I have reviewed: The SVS PB-2000, SVS PC-2000
, and Klipsch R-115SW
. On the other hand, it offers DSP while the others do not, which is a huge advantage. As far as smaller subs go, the S12EQ is quite similar (performance-wise) to GoldenEar's ForceField 5
—another 12-incher with a down-firing passive radiator.
After I Auto-EQ'd the S12EQ, its fidelity was commendable, producing a smooth measured frequency response at the listening position. When used in a system without subwoofer EQ or bass management, it sounded better than the other subs I just mentioned.
I spent the bulk of this review using the S12EQ in conjunction with the SC-85 AVR. It's the same 2.1 system featured in the review of the ELAC Debut B6 bookshelf speakers, and it exceeded my expectations for price versus performance.
In order to test the S12EQ's effectiveness when used in a surround system, I fed it a steady diet of action films and video games. In that setup, the SC-85 took care of processing and main-speaker amplification while a KEF R-Series Atmos system turned that electricity into sound.
During gameplay, I particularly appreciated how the sub added a physical element to the experience; I could feel every explosion and impact in Grand Theft Auto 5 and Need for Speed 2015. As for movies, I checked out scenes from a number of recent releases including Everest, Jurassic World, Straight Outta Compton, Ant-Man, and The Martian—all of those movies benefitted from the added impact afforded by the sub. I'm sure there are a few isolated instances in the movies where the bass dipped below what the S12EQ could deftly handle, but I'm also sure those instances would be very rare.
During my evaluation, I checked out the Cinema mode and found it added even more chest-thumping impact to the movie-watching experience, but I also felt it was unnecessary so I stuck with the Normal setting. The same held true for the Music mode; it added extra kick to the low end, but ultimately I felt the sub didn't need the extra boost.
The S12EQ turned out to be a great option for use with high-performance soundbars that don't come with their own subwoofer but offer the option to add one. I used it in my recent review of MartinLogan's Motion Vision X, and with a simple Auto-EQ calibration, it integrated seamlessly—a trick none of the half-dozen other subs I had available could pull off.
I took some basic measurements with REW to see how they correlated to my subjective listening experience. A close-mic'd sine-wave sweep (with EQ disabled) yielded a flat response, as one would hope. Another measurement taken at the listening position (again, with EQ disabled) revealed a sizable null centered around 55 Hz, and the output was 12 dB higher at 22 Hz than at 80 Hz.
After enabling Auto-EQ, a close-mic'd measurement showed a response curve that included a peak at 55Hz, indicating that it was attempting to compensate for the null. Another measurement from the listening position (with Auto-EQ enabled) showed a much flatter in-room response. While the null was still there (you can’t EQ your way out of one), it covered a much narrower range of frequencies that it did before calibration.
The REW readings matched up well with what the app reported it did: boost the frequencies surrounding the null (40-60 Hz) by 6 dB and attenuate frequencies below that by 6 dB.
This graph shows the EQ curve created by the ELAC app.
While I was measuring frequency response, I peeked at distortion levels (close-mic measurement, 100 dB, no EQ) and found that at 24 Hz, THD was already under 5% and quickly dropped to less than 1% by the time the frequency reached 35 Hz. In practical terms, that means distortion stayed under audible thresholds.
In the process of writing this review, I occasionally felt like I was not adequately conveying exactly how awesome the S12EQ is. It takes a laborious task—obtaining flat bass response at the listening position—and makes it as easy as pushing a few buttons on a smartphone or tablet. In the world of subwoofers, that's a big deal.
The ELAC S12EQ's performance is so good, it would be a good value l even if it were a "dumb" subwoofer that did not offer EQ. Add the value offered by its app-controlled DSP functionality, and quite frankly I can't think of another sub-$1000 subwoofer that offers as great an ownership experience right out of the box. There are other subs that offer some form of automated calibration, but they typically cost a lot more and require the use of a dedicated, corded microphone.
ELAC's Debut S12EQ is an exciting new option in the world of subwoofers for anyone seeking a full-featured bass-making machine that doesn't break the bank. While it's not going to thrill folks seeking infrasonic capabilities, its bass reproduction within the audible spectrum is both powerful and polished.
Sony PlayStation 4
Windows 10 laptop
Amps and Processors
Pioneer Elite SC-85 AVR
ELAC Debut B6 bookshelf speakers
KEF R500 towers
KEF R100 bookshelf speakers
KEF R200c center
KEF R50 Atmos modules
SVS Prime towers
Paradigm Prestige 75F towers
MartinLogan Motion Vision X soundbar
Android and iOS Devices
Samsung Galaxy Note 5
Samsung Galaxy Tab Pro
Samsung PN64F8500 plasma TV