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Q. Which subwoofer would you choose?

Published November 2018
By Hugh Robjohns

I have a pair of Focal SM9 monitor speakers and am wanting to add a subwoofer. I’m torn between the Focal Sub‑6 and ADAM Sub‑10 Mk2. My application is basically for playback/DJ’ing vinyl records in my small, treated home studio. The price of the Focal is almost twice that of the ADAM, in which I can get a pair if I choose the latter. My aim is to have a well‑rounded sound, with tight bass but not harsh to the ears. What would be my best bet: a single Focal Sub‑6, or a pair of ADAM Sub‑10 Mk2s?

Mike, via Facebook

SOS Technical Editor Hugh Robjohns replies: First and foremost, subwoofers and small rooms very rarely work together well. Small rooms always have problems with prominent room modes (low‑frequency standing waves) which can only really be resolved with a great deal of properly effective bass trapping — and that is always very difficult, if not impossible, to achieve in a small room. A couple of bits of foam in the corners won’t cut it, I’m afraid!

When buying a sub for critical monitoring, it can make good sense to buy the same brand as your monitors — but note that in small rooms subs can actually make bass problems worse.When buying a sub for critical monitoring, it can make good sense to buy the same brand as your monitors — but note that in small rooms subs can actually make bass problems worse.If the room’s low‑frequency acoustics are not well sorted then introducing a subwoofer will make the low end sound even more lumpy (some notes will boom and others will almost disappear) than without, and judging the balance of your mixes will become even harder than without a subwoofer.

Also, beware low‑cost subwoofers. All loudspeakers introduce harmonic distortion to some extent, and the harmonic distortion from a subwoofer inherently sits all across the mid‑range, making it harder to hear the real mid‑range detail from your speakers.

Subwoofers are not all equal by any means, and the cheaper the subwoofer the greater the liklihood of more distortion products. So while you may gain some bass extension and LF power by adding a sub you may also lose some mid‑range clarity and resolution...

A good, clean (low distortion) subwoofer is not easy to design or build, and I’m yet to hear anything I’d want to use in a critical monitoring system costing less than about £1200 $1500.

Also, sticking with a subwoofer that is specifically designed to match your satellite speakers makes a lot of sense, as the manufacturer will have already worked out how best to integrate the two systems in terms of crossover frequency, filter slopes, and phasing.

So given the options listed, I’d go for the Focal sub without a doubt — but only if the room really, genuinely, honestly has a very well‑sorted low‑end response. I know big shiny boxes are attractive, and the idea of deep, visceral bass is beguiling, but in a small room it may well prove a very expensive mistake. In such situations, a good quality set of headphones often proves to be a far more accurate and reliable way of assessing the low‑end balance of mixes, in my experience.

Published November 2018