The latest company to rise to the challenge is a small Bridgend firm called REL Acoustics, which has come up with an unusual subwoofer called Stygian. It's unusual because built into the back of the 72 litre enclosure are three knobs that let you adjust crossover frequency and gain.
Two of the switches, marked 'fine' and 'coarse', allow you to select on of 16 crossover frequencies ranging from 30 to 120Hz, with the lower operating frequency fixed at 25Hz. The other button marked 'gain', adjusts the sensitivity of the 100 watt subwoofer from 2 to 30V. Richard Lord, the engineer behind REL says that by experimenting with different crossover frequencies and then adjusting the gain to a sensitivity approximating that of you main speakers, the subwoofer can be tuned to match you room and your system.
So much for the theory; how would the Stygian perform in my own modestly sized, brick walled room? I decided to test it with two sets of speakers: the Heco Superior 750, a floorstanding model with good bass reproduction down to 28Hz, and Tannoy E11's, a fairly typical bookshelf speaker with a more modest range.
I slid Gonna Make You Sweat into the CD player. With the subwoofer turned off, the bass on tracks like Everybody Dance Now sounded more than adequate, driving the musicalong without swamping the higher frequencies. I was dubious whether the subwoofer could improve things.
With the crossover set to its lowest position, 30Hz, and the gain at minimum, the Stygian merely murmured. But by slowly increasing the gain, it was possible to match its amplitude to that of the main speakers. The result was an uncomprimising bass that growled menacingly but stopped short of blanketing the rest of the music.
When the crossover frequency was increased above 43Hz the subwoofer became unstuck. Even with the gain set to its lowest position, the bass was so powerful I couldn't bear to listen to it for more than a few minutes.
One of the principles of a subwoofer is that you can place it anywhere in the room without destroying the stereo image, because the brain cannot locate the source of very low frequencies. But when the Stygian was set to its highest crossover point, I could clearly hear it reproducing some of the vocal frequencies; it ceased to blend into the stereo plane and instead acted as a third speaker.
So long as the crossover and gain were set low, I found the subwoofer worked well with a variety of music.
The Stygian does live up to its manufacturer's claims. It worked well with both pairs of speakers and seemed to lose little from the complexity of its filters. But it is not cheap and is only available by mail order.
Richard Baum