REL No.31 Reference Series Subwoofer
No.31 — Compact Reference Subwoofer
No.31 exists to satisfy the needs of those who crave the finest yet have space limitations. Whilst some can afford our flagship No.32 model, it is larger and deeper than some rooms can accommodate. How can you best deliver No.32’s sound quality, build quality, and thoughtful features with a more compact footprint? Enter No.31.
Perfection Repeated
No.31 matches No.32’s design stroke for stroke, yet somehow it manages to look more svelte, crouching closer to the floor—almost feline in its grace. The elegant plated handles inset into an ellipse are retained, as is the string grille that permits vast amounts of air to explode into your room without creating noise like cloth grilles can. No.31 features the curvilinear radius to the sidewalls that define both its performance and its character. But the reduction in visual and actual three-dimensional physical mass is remarkable. No.31: when the best must be delivered in a smaller space.
Drive This
The incredible excursion of the 12" pure carbon fibre driver allows it to play as loud as its larger stablemate. Yet, the No.31 possesses the tactility, nimbleness, and attack that only the greatest subwoofers have ever been able to deliver. Its sonic signature works in modestly scaled rooms and with a vast range of fine speakers.
The driver is accelerated by a specially wound 3" voice coil driven by a 13-pound magnetic structure; even near its limits, the voice coil remains solidly inside the gap. It is this visceral power, coupled with great delicacy and nuance, that is No.31’s signature.
Amplified Perfection
No.32’s NextGen 7 Class D 1,000-watt amplifier also lives inside No.31, only limited to 900 watts to ensure the perfect complement to the 12" bass engine within No.31. This allows the maximum dynamics to be delivered while ensuring a long, cheerful life for both components.
Here too, the LimitLess Limiter™ — which permits the amplifier to tiptoe right up to its limit without audible compression — conveys a rhythmically effortless quality. Dual parametric filters allow precise micro-tuning; the deepest bass can be slightly reinforced, while the upper ranges of bass can be gently trimmed to ensure a brilliantly rendered transition from bass to the main speaker. The electronic design of the reference range is itself artistry.
Arrayed for Battle
No.31 permits the same vertically stacked line array as the ultimate No.32. It delivers transformative performance that no competitor has been able to match. For those seeking the ultimate musical and theatre experience, line arrays unlock the final dimension of system reproduction.
Experienced listeners have chased three-dimensional sound for years, yet they have missed the simple fact that height — not depth — of image is the missing link. By creating products designed to be stacked three (or in exceptionally tall rooms, five) units high while retaining individual crossover and gain control of each subwoofer in the array, REL has created a masterpiece that finally delivers what the most experienced listeners have been chasing for the past 40 years.
A Remote Like No Other
Take control of your No.31 with the REL Reference Remote Control. Immediately you will be struck by the perfect fit in your palm — the result of careful thought and generations of prototype refinement. The mass of the remote conveys its quality, permanence and immutability. It tells you: “I am a thing of substance. Pay attention — what you do next matters.”
If you have owned a REL in the past (and a large majority of Reference owners have), all the familiar controls are right at hand. High (or low, if using active speakers) level gain sits comfortably to the right, the crossover rests in the middle, and .1/LFE gain is off to the left.
Below are three metal toggle switches that handle critical setup functions. The remote’s on/off switch sits at the bottom — out of the way — and remains on during setup without being accidentally turned off. The phase control sits in the middle for initial 0°/180° setup. Top access to the Dual Parametric EQ — marked A and B — permits the flattest, deepest bass and the fine-tuning of crossover behaviour at the top end of the bass frequencies. This gives you the perfect blending of subwoofer to main speakers and allows any vestiges of room-generated boom and resonance to be gently trimmed away.
REL’s Reference Remote is like the perfect butler — immaculate, indispensable when called upon, then quietly set aside until a future time when system additions or improvements require its services.
Key Specifications (summary)
• Driver: 12" pure carbon fibre
• Voice coil: Specially wound 3"
• Magnetic structure: 13 lb
• Amplifier: NextGen 7 Class D — 900W (No.31 limited)
• LimitLess Limiter™ and Dual Parametric EQ
• Line array capable — stack 3 (typical) or up to 5 in very tall rooms
For demo and availability at Audio T—including in-store demonstrations and expert system advice—contact your local Audio T branch.
Technical Specifications — REL No.31
Type: Closed box, front-firing driver
Active Driver Size & Material: 12 in. (300 mm) long-throw, carbon fibre cone with inverted carbon fibre centre cap, die-cast alloy chassis
Passive Radiator Size & Material: N/A
Low Frequency Extension: 17 Hz at -6 dB
Input Connectors: High Level Neutrik Speakon; Low Level (2) RCA; (1) LFE RCA; (1) LFE XLR
Output Connectors: High Level Neutrik Speakon; (1) Low Level RCA; (1) LFE XLR; (1) Line XLR
Power Output: 900 watts (RMS)
Amplifier Type: NextGen 7 Class D
Wireless Capability: REL AirShip II (sold separately)
Dual Parametric Filter: Yes
Finish: Piano Black Lacquer, 12 coats
Protection System — Fully Electronic Set Safe: Yes
D.C. Fault: Yes
Output Short: Yes
Mains Input Voltage: 220–240 volts; 110–120 volts for certain markets
Fuses: 7 Amp semi-delay (230 V operation); 15 Amp semi-delay (115 V operation)
Supplied Accessories: Mains lead — Yes; Neutrik Speakon — Yes (10 metres nominal); Interconnect — —; User manual — Yes
Dimensions (W × H × D): 25 1/8 × 17 × 28 1/2 in (638 × 435 × 720 mm)
Net Weight: 114.5 lbs (52 kg)
Shipping Weight: 156 lbs (71 kg)