REL No 31 subwoofer

REL’s Reference Series of subwoofers is just two models. These are the REL No 31 subwoofer tested here and the bigger No 32. These can also be stacked in line arrays. Given the bass power from a single No 31, I wonder what a sextet of No 32s can do. Jostle a few buildings around, perhaps. Or maybe enough sonic push to shove-start a Boeing.

What these Reference Series subwoofers do is the same as what REL’s other subwoofers can do but with more! More grace, power, speed, polish, and – when needed – air movement. However, it doesn’t feel like the REL is moving more air. Then you feel the waves of bass energy washing over you. That’s why the REL No 31 subwoofer is very special.

Specs!

The specification sheet of the No 31 is a heady and potent brew of superlatives. The 52kg subwoofer includes a 300mm long-throw driver, 900W of Class D oomph, and low-frequency extension to 17Hz (at -6dB). And yes, you can stack up to three atop one another with the appropriate mounting kit. The No 31 and 32 share a similar comprehensive rear panel for line and speaker level connection. This allows stacking and stereo connections. There’s a helpful hockey-puck remote control and a stringy-grille front panel in the style of classic Italianate loudspeakers. There is also a front panel display and grab handles on the side. Fortunately, the handles are sufficiently wide apart that only an idiot would try lifting the No 31. However, handles make moving the loudspeaker across carpeted floors less hernia-inducing.

The extra £3,000 buys you the No 32 with its kilowatt of Class D power, a 380mm driver that reaches down to 15Hz and an 85kg weight. Oh, and where the REL No 31 subwoofer is finished in high-gloss black, the No 32 goes with piano lacquer. You can stack No 32s, but you can’t mix and match.

So, the No 31 is a No 32 for slightly smaller settings and bank balances, but if you think that spells ‘compromise’, guess again. If anything, the No 31 is in a sweet spot, balancing size, performance, and price. This makes it the ideal choice for all barring the vastest of rooms, the most esoteric of systems and the deepest of pockets.

REL No 31 subwoofer: Not just for Bass Dogs

Sure, the temptation to cry ‘Havoc!’ and let slip the dogs of bass is irresistible. You are going to want to experience the almost malevolent power of bass. I did this with ‘Insomnia’ by Faithless, first with the backbeat and then that almighty reverb-heavy drop… wow! Anything not tied down is on the move. Bits of your body shift around that should stay in position. Also, sheer force reminds you of the first time you heard that track in a club somewhere. The volume level might not be club-level, but the intensity and energy remain.

Then, your audiophile sensitivities begin to kick in once more. You should know the drill by now; you turn it down to be a barely audible low-frequency support for your loudspeakers… and then readjust a few weeks later to be sure. Fortunately, the remote makes this easy and can be locked to prevent someone from fiddling about unnecessarily. And in turning the subwoofer into audiophile base reinforcement, the REL No 31 subwoofer shows its true colours well.

That bass foundation is solid granite, an architectural stentorian solidity that makes the music seem more realistic and a more visceral experience. But that is an extension of performance into the midrange and treble. A good sub makes loudspeakers sound like they are on cruise control in all the right ways. The midrange is more open and yet also more focused and articulate. Held in the No 31’s thrall, however, those loudspeakers take that articulation, detail and focus to new heights and extend that well into the treble. The jump between low, mid, and high-frequency drivers is more seamless, and even the most minor peaks seem less noticeable.

Not only stand-mounts

This isn’t simply used with smaller stand-mounts; The No 31 partners well with the excellent Raidho TD2.2, itself no stranger to bass definition and mid-range and high-frequency clarity. And yet, even here, the No 31 showed these speakers have more to give when freed from having to produce their foundation. The transformative effect a good subwoofer can bring is well known, but the improvement the No 31 delivered still manages to surprise. This is a good sound, transformed. And all it takes is a subwoofer the size of a car engine!

The REL No 31 subwoofer is an iron fist in a velvet glove. Like all good subwoofers designed for audio use, it’s subtle enough to subtly reinforce the bottom end of almost all loudspeakers in every room that isn’t a concert hall. That last isn’t simply a throwaway line; adding the No 31 to your system is like adding concert hall space and realism to your loudspeakers. Naturally, no one – make that ‘no one sane’ – thinking of using a £7,000 subwoofer will connect it to a pair of £200 bookshelf loudspeakers. Still, speakers in line with the No 31 will already deliver the goods… and adding the No 31 will transform even high-end designs in ways you might not expect.

To say I was impressed by REL’s No 31 is an understatement, but curiously the No 31 is all about understatement. Sure, it can move a lot of air when called upon, but it’s at its best when making great loudspeakers sound much better than expected. For all its size, weight, and power, the No 31 is a genuinely graceful performer that can bring out the best in your system.

REL No 31 subwoofer Technical specifications

• Type Active subwoofer
• Output connectors High Level Neutrik Speakon, LFE XLR, Line XLR
• Amplifier type 900W, Class D
• Driver 300mm long throw carbon fibre cone with inverted centre cap
• Low frequency extension 17Hz at -6dB
• Dimensions (W×H×D) 63.8 × 43.5 × 72cm
• Weight 52kg
• Price £7,000

Manufacturer

REL

+44 (0) 1656 768777

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