Focal: Sub One Active Subwoofer

It may be a rhetorical question, but when did it become necessary to integrate a subwoofer into our monitoring setups? I can remember a time in the early 2000s when subs seemed more of an inconvenient “option,” one that seemingly interfered with session efficiency instead of offering a helpful look at frequencies that I often ignored – what a silly engineer I was! Early in my audio career, I naively decided it was better to avoid what I couldn’t hear than to deal with it. Aren’t two speakers difficult enough? In the busy studio where I was working, the same subwoofer sounded different on almost every session. Maybe the last engineer turned it up too loud or threw it out of phase? Perhaps it was never configured correctly in the first place? The answer was that frequencies below 80 Hz simply confused my dumb ears, and the subwoofer was definitely not configured correctly – for me, anyway.

The question “to sub or not to sub?” is no longer a question – it’s definitely “to sub.” Consumer playback systems (not counting your phone) have improved low end response these days, plus surround and Dolby Atmos configurations require a subwoofer. So, unless you plan on living under a rock for the rest of your life, you’re going to have to deal with the low end. On the plus side, subwoofers take care of your bottom’s bottom end and let your loudspeakers do what they do best: project the high and mid-bass frequencies. What I (stupidly) used to consider a luxury item is now a necessity, and up until recently I would argue that there hasn’t been much of a middle class in low end support.

Enter the Sub One all analog (no DSP) active subwoofer, designed to accompany (but not restricted to) Focal’s affordable Alpha Evo [Tape Op #145] and mid-priced Shape [#126] monitor lines. Equipped with two side-firing eight-inch double-skinned slatefiber (more on this later) cone drivers, and powered by a pair of low distortion 100 watt Class D amplifiers, the Sub One offers a big, pro studio sound at a small studio price. Of course, price is always relative to what you have left in your wallet at the end of the month. However, once you’ve struggled with an entry-level subwoofer, saying “goodbye” to your hard-earned cash will hurt a little less when you feel the difference in playback and experience the confidence of mixing with accurate low end. I frequently use the word “feel” rather than words like “hear” or “sound” when describing a subwoofer – I don’t want to really hear it – or even see it, for that matter – I don’t even want to know it’s there.

Though the Sub One can’t be described as small (19x12x20-inches), its dual front port design and built-in rubber feet allow for sneaky placement right up against the wall or under a desk, which is where I put it in my project studio. Controls and connections are located on the rear of the sub. Options for integration include XLR input and output ports for LFE (low-frequency effects) setup within a surround (or Atmos) matrix or as a sub-bass in a 2.1 configuration. I opted for the latter, taking advantage of the Sub One’s built-in adjustable low-pass crossover to set the sub response and switchable (60 or 90 Hz) high-pass crossover for the mains. Additional controls include adjustments for level and phase, plus a polarity switch. An input for a bypass footswitch and output for linking to additional subwoofers are also provided. I appreciated the simple Enable/Disable Auto Stand-by switch. True to the Sub One’s aesthetic of disappearing into the shadows, the only power indication is a small, dimly lit LED near the top rear of the unit. Power switch and an IEC power connection are also located on the back.

Over the course of an hour, I adjusted crossovers and phase by ear, then ran some pink noise through my system to calibrate the loudspeaker level with my trusty old RadioShack Sound Level Meter to about 6 dB hotter against the Sub One. I continued to tweak to taste, then recalibrate for a few more days. Reaching behind a heavy subwoofer under a desk against a wall is never fun, but it is a reality – and once you get things set, you don’t want to bump any controls. Though not directly related to this review, lately, I’ve been using a Wobsion LED Lighted Travel Makeup Mirror ($9.99; amazon.com) for poking around behind monitors and racks.

The Sub One’s frequency response is rated at 32 to 120 Hz. In use, the subwoofer’s low end extension felt smooth, natural, and expensive. I did my testing with Focal’s Alpha 65 monitors [Tape Op #104] as mains. The newer Evo class professional Focal monitors, including the just-introduced Alpha Twin Evo and the Sub One, employ slatefiber woofer cones with an aforementioned Class D amplifier. Focal’s slatefiber cone technology is a composite of recycled non-woven carbon fibers and thermoplastic polymer, which offers high rigidity, resulting in increased accurate bass response. The thermoplastic polymer bonds the fibers, which also improves damping. Because carbon fibers are very light in mass, the resulting speaker driver’s sensitivity is also optimized. So, what does all this have to do with a subwoofer? Definition. At no time did I feel like playback was ooze-y or subwoofer-y. It was just good, fully integrated, solid low end.

I could go on about how well my mixes were referencing and how happy my clients were, etc., but instead, I want to talk about my confidence level and efficiency. We all go through our mix struggle phases. One month all my electric guitars sounded weird. For a few weeks, I might be boosting too much high end. Why did every song I mix this summer have the overheads up too loud? Kick and bass guitar are struggles I go through on every mix, which is why I was excited to get the Sub One into my space. By providing a natural separation between the presence and “boom” of a low end source, my choices became immediately obvious with the Sub One in place. I spent some time reviewing recent mixes that I wasn’t happy with, and in most cases, they were improved with simple adjustments – now that I could feel the low end energy moving in my room correctly. Surprisingly, I could often hear where I was over-compressing at problematic frequencies and where release times were completely wrong! When your sonic world opens up (even just a little), a wash of voices screaming, “What were you thinking” rains down on your head while you gape open-mouthed at your previously poor and sonically underinformed decisions. The shortcomings of your playback system are always in the back of your mind, whether you’re consciously aware of them or not. You make adjustments and decisions based on those shortcomings. With no reliable low end below about 80 Hz, I’ve been hedging my bets for the last two years. With the Focal Sub One upgrade to my playback system, I’m now confidently reaching for better sounds.