REL Reference No. 31 Subwoofer

The REL No. 31 is a masterpiece of audio engineering, a reference subwoofer that balances profound power with incredible speed and nuance. It is designed for those who seek the ultimate in low-frequency reproduction but whose system or room demands proportion and restraint. The No. 31 distills the essence of the flagship No. 32 into a more compact form, combining a 12-inch pure carbon fibre driver with a 900-watt reference amplifier. This potent combination, housed in an acoustically perfect, curved cabinet, delivers bass that is devastatingly deep yet agile and articulate. Purpose-built for seamless integration with the world's finest loudspeakers and capable of being stacked in Reference Line Arrays, the No. 31 delivers a truly three-dimensional, full-range listening experience.

Key Features

• 12” Pure Carbon Fibre Driver: A 350mm long-throw driver with an inverted carbon fibre cone for immense stiffness, allowing it to remain pistonic over its entire 4" (100mm) of travel.
• 900W Reference Amplifier: A dedicated 900-watt (RMS) Class D amplifier provides massive power reserves and absolute, iron-fisted control over the driver.
• Reference High Level Input: Employs REL’s legendary High Level connection with specialized, reference-grade filters for a perfect, seamless blend with main speakers.
• Dual Parametric Filters: A sophisticated EQ system allows for precise in-room tuning at both the deepest and upper-bass frequencies for flawless integration.
• Reference Line Array Capable: Engineered to be stacked in vertical line arrays of three (or more) units per side for the ultimate, floor-to-ceiling bass performance.
• Acoustically Inert Cabinet: A massively braced, curved-ply cabinet finished in 12 coats of hand-rubbed piano black lacquer to eliminate resonance and standing waves.

The Heart of Carbon Fibre

The soul of the No. 31 is its remarkable 12-inch (350mm) pure carbon fibre driver. This driver is a true engineering marvel, designed for both brute force and extreme agility. The entire cone structure is forged from carbon fibre, a material chosen for its incredible stiffness-to-mass ratio. This allows the driver to withstand the immense pressures generated by its 900-watt amplifier and 4 inches (100mm) of excursion, moving as a perfect piston without flexing or deforming. The result is bass that is not only incredibly deep but also lightning-fast, textured, and free of the distortion that plagues lesser designs.

Limitless Power, Effortless Control

To animate its reference-grade driver, the No. 31 employs a dedicated 900-watt (RMS) Class D amplifier. This powerhouse is specifically designed to provide the massive, instantaneous current required for deep, dynamic bass. Its vast power reserves mean it operates in a state of effortless control, providing the iron-fisted grip needed to start and stop the 12-inch cone instantly. This is further enhanced by REL’s LimitLess Limiter™, which allows the amplifier to operate up to its limits without audible compression, ensuring that the rhythm and flow of the music are always preserved.

Perfect Integration, Perfect Sound

The No. 31 features REL’s renowned High Level Input, allowing it to receive the exact same signal—including the tonal character and sonic signature—as your main speakers. This is the key to REL's seamless integration. For this reference model, the signal is fed into a set of specialized filters developed for the Reference Series. These are complemented by a powerful Dual Parametric EQ, which allows for micro-tuning of the subwoofer. You can gently reinforce the deepest frequencies while precisely trimming the upper-bass crossover point, achieving a blend between the subwoofer and main speakers that is perfectly coherent and utterly inaudible.

The Reference Line Array: The Final Dimension

While a single No. 31 is a reference performer, its design anticipates the ultimate in audio reproduction: the Reference Line Array. The No. 31 is engineered to be vertically stacked in arrays of three (or five, in exceptionally large rooms) units per side. This approach mimics how sound is produced in a live performance, creating a floor-to-ceiling wavefront of bass that pressurizes the room more uniformly and with greater ease. This doesn't just mean more bass; it means a more open, three-dimensional soundstage, with greater clarity and focus across the entire musical spectrum. It is the key to unlocking the final dimension of your system's performance.

A Cabinet of Pure Artistry

The No. 31’s enclosure is a critical component of its performance, sculpted to be as acoustically inert as it is beautiful. The gently curved, 2.4-inch (60mm) thick walls are constructed from layered hardwood and are massively braced internally to create a silent, rigid vault. This curved form eliminates internal standing waves, preventing the cabinet from "singing along" with the music and coloring the sound. Each cabinet is then painstakingly finished in 12 coats of hand-rubbed piano black lacquer, a process that takes three weeks to complete, resulting in a finish as deep and pure as the bass it produces.

The Listening Room Difference

We’re a third-generation family business with a brick-and-mortar showroom in Chestertown, Maryland, and a reputation built on trust, not hype. Whether you’re visiting in person or ordering online, we bring decades of experience, personalized service, and honest guidance to every interaction. We don’t just ship boxes. We help build systems, answer your questions like real humans, and make sure every detail of your setup is right, from the cables to the final connection. Our passion is helping you get the most out of your gear, with support that lasts well beyond the sale.

Specifications