No.31

The REL No.31 is a high-end subwoofer for listeners who need Reference-level performance in a more compact enclosure than the REL No.32. It uses the classic Reference filter found in the No.32, dual parametric filters and a driver that handles 3 times the power of the previous design. The result is a subwoofer designed to deliver the No.32’s sound quality, build quality and features where a larger, deeper cabinet cannot be accommodated.

The No.31 follows the design of the No.32, with a lower, more compact form. Its plated handles are inset into an ellipse, while the string grille allows substantial airflow without the noise associated with cloth grilles. Curved sidewalls define the enclosure’s appearance and contribute to its performance, while the reduced physical mass gives it a smaller visual and actual 3-dimensional footprint.

REL No.31 can be used in the same vertically stacked line array configuration as the No.32. Systems can be built with 3 units, or 5 units in exceptionally tall rooms, with individual crossover and gain control retained for each subwoofer. The line array design addresses the height of the reproduced image as well as its depth, giving music and home theatre systems a further dimension of reproduction.

The 1,000 watt amplifier used in the No.32 is also fitted to the No.31, where it is limited to 900 watts to complement the 12” bass driver and support the long-term operation of both components. REL’s LimitLess Limiter™ allows the amplifier to approach its limit without audible compression. Dual parametric filters provide precise adjustment, with the deepest bass slightly reinforced and the upper bass gently reduced where required to create a clean transition to the main speakers.

The 12” pure carbon fibre driver has extensive excursion and can play as loudly as the larger No.32. Its driver motor uses a specially wound 3” voice coil and a 13-pound magnetic structure, keeping the voice coil securely within the gap even close to its limits. The No.31 combines physical impact with fine control and operates effectively in modestly sized rooms with a wide range of high-quality loudspeakers.

The REL Reference Remote Control provides adjustment of the No.31 from the listening position. Its shape was developed through multiple generations of prototype fitting, with a substantial feel in the hand. The familiar controls are arranged for direct access. High-level gain, or low-level gain when active speakers are used, is positioned on the right. The crossover control is in the centre, while .1/LFE gain is on the left.

3 metal toggle switches control the main setup functions. The remote’s on/off switch is positioned at the bottom, where it remains accessible during setup while being less likely to be switched off accidentally. The centre switch selects phase, with 0 or 180 degrees used during the initial setup. The upper switch accesses the Dual Parametric EQ, marked A and B, for adjusting bass depth and crossover behaviour. These controls allow the subwoofer to be integrated with the main speakers and reduce room-generated boom or resonance where necessary.

The remote can then be set aside until further system changes or additions require adjustment.