REL S812

The S812 belongs to the S range from the British manufacturer REL, which specialises in subwoofers intended for both music reproduction and home cinema. Its role is to take over from the main speakers in the lowest register of the spectrum, where most floorstanding and bookshelf speakers begin to run out of breath, in order to restore the foundation and sense of air that an installation relying solely on its speakers may lack.

This is an active subwoofer: the amplification is built into the cabinet, which avoids drawing power from the main amplifier and allows the level and connection to the rest of the system to be adjusted independently. This architecture also explains why a subwoofer of this type is set up alongside the system, once the speakers are in place, rather than replacing them.

The S812 is aimed at those who already own speakers they are happy with and are looking to extend their response downward without changing them. In mixed use, for music and films alike, it adds extra substance to low percussion, organs, double basses and the low-frequency effects of soundtracks. An option is also available to do away with the cabling between the source and the subwoofer.

• Airship II kit: wireless transmitter available as an option

When buying a used subwoofer, attention should first focus on the driver: a membrane free of tears, a suspension that is supple and free of cracks, and no rubbing of the coil when gentle, even pressure is applied to the cone. The built-in amplification module deserves equally careful inspection, as it is the part that ages worst on this type of unit: listen for the absence of hiss or hum at rest, check that the subwoofer comes out of standby correctly, and that the level and crossover frequency potentiometers do not crackle when adjusted.

The cabinet itself should be checked at the edges and corners, which are particularly exposed when handling a heavy unit, and at the seals around the driver and the rear panel. Finally, check that the original connection accessories are present, as the high-level connectors specific to REL subwoofers form part of their intended method of connection.