Group test: Subwoofers

Subwoofers as a breed are generally much better now than they were just a few years ago. Most are more compact, and rely less on reflex ports to ensure respectable bass extension, which generally means a smoother, better behaved bass from designs that don't take up disproportionate amounts of space. It also means easier set-up and less 'room boom', especially in stereo music systems (where subwoofers have traditionally often failed to sound at home), though careful set-up once the subwoofer is fully run is still essential.

This test covers four models, costing from £250 - £600, that should suit a wide range of systems designed for either stereo or multichannel replay - or both.

Overview Price: £600 More info: KEF Size: 450(h) x 600(w) x 395(d) mm Weight: 22.5kg Type: sealed box (IB) downwards firing active subwoofer Driver: 300mm Power output: 300 Watts Frequency response: 30Hz-250Hz, +/-3dB Connections: stereo phono (line level) input, stereo line level high pass filtered output KEF PSW3500 By a big margin the largest model in our four-strong group, with a footprint about twice the size of its nearest competitor, the PSW3500 offers the promise of a more extended and weighty bottom end than the others. It also has the best facilities on tap in the form of a music/cinema switch (in fact the cinema setting is all but unusable in practice), and more user adjustments to help fine-tune the subwoofer in different systems. The list includes a high-pass output, prefiltered to work with smaller satellite speakers, though larger speakers are the PSW3500's preferred partners. The large oval cross section is not a styling gimmick by the way, it is there to ensure the internal reflecting surfaces are as irregular as possible which should (and does) mean a smoother, less boomy bottom end. Although the REL T2 runs the KEF closer than you might expect from its more compact dimensions, the KEF does indeed offer the biggest bang for your buck. It is an imposingly powerful animal which digs deep into the recordings it is playing to extract the acoustic, and adds to the sense of tonal colour and variety, as well as providing a real sense of authority and depth to even quite large (eg medium-sized floorstanding) loudspeakers.

Verdict Plus points Well endowed, well built subwoofer with real muscle Minus points No chance of hiding this one away in the corner

Overview Price: £229 More info: MJ Acoustics Size: 332(h) x 278(w) x 278(d) mm Weight: 11.5kg Type: sealed box (IB) downwards firing active subwoofer Driver: 250mm Power output: 120 Watts Frequency response: 13Hz-200Hz, (no limits stated) Connections: phono (LFE level), Speak-on (speaker level) both with dedicated volume controls

MJ Acoustics Pro 50 Mk II
Very similar in presentation to the Tannoy TS8, closer examination shows that the satin-finished Acoustics Pro 50 Mk II is physically larger (though it's still a compact), that it accommodates a larger bass driver and that it weighs almost twice as much, all of which means a more extended low-frequency bandwidth (though subjectively not by as much as the numbers suggest), an enhanced ability to play at higher volume settings (with a similar caveat), and a cleaner more accurate bass output.

Indeed this is the MJ's greatest strength, though again the model has clear limitations as the volume is pressed higher, and the Pro 50 Mk II quickly settles into high levels of audible distortion if the volume is set too high. The unit has separate volume settings for the two inputs (speaker and LFE level) which means it is easily set up to suit stereo and multichannel replay.

Performance is good when measured against price, but if you can afford the admittedly hefty extra bill for the REL T2, the investment will be well justified, especially when the subwoofer is used for stereo low frequency reinforcement. At moderate levels, however, the Pro 50 Mk II is sharp and precise, with a surprisingly powerful low-frequency reach and it packs a disproportionate punch.

Overview Price: £495 More info: REL Size: 375(h) x 335(w) x 394(d) mm Weight: 15kg Type: ABR - downwards firing powered driver with forward firing passive (acoustically coupled) unit Drivers: 203mm active unit, 254mm passive unit Power output: 200 Watts Frequency response: 30Hz-120Hz (no limits stated) Connections: phono (LFE level) with dedicated volume control, XLR balanced in/out

REL T2
If one company can be said to have triggered the interest in subwoofers over roughly the last decade, it is REL, which is based in Wales, though the company is now US-owned. The T range is the first major introduction under its new ownership, but although many of the details have been changed, the thinking is clearly in line with its predecessors.

REL continues to advocate wiring the T2 parallel with the main speakers to ensure both see exactly the same input, and to use the main speakers full range, just bringing the subwoofer up to meet their low frequency limit, which generally means that the subwoofer is limited in its reach to those frequencies the satellite cannot manage on its own.

The result is a much better integrated output with better reach than most similar combinations, and a more transparent sound quality, a combination which, with careful set-up the subwoofer simply adds depth and power without sounding loose, boomy or in any other way at odds with the main speakers.

This alone means it works much better in a music-first system, but there is enough depth and weight, and flexibility in the inputs and controls to ensure it works well in a full-on multichannel system.

Overview Price: £250 More info: Tannoy Size: 292(h) x 280(w) x 255(d) mm Weight: 7kg Type: sealed box (IB) downwards firing active subwoofer Driver: 200mm Power output: 200 Watts Frequency response: 50Hz-150Hz, -6dB Connections: Stereo XLR balanced in/out, phono stereo line level in

Tannoy TS8
The compact matt grey TS8 has some semi-professional studio pretensions. The wide range of socketry (which includes a set of studio type balanced XLR in and outputs) means the Tannoy is easily set up for use singly or in multiple configurations in virtually any kind of system, though at the price there's a limit to what the designer can achieve.

In particular, the Tannoy retains the sealed box acoustic loading which is a feature of all but one of the test models here, and this helps ensure a tighter, more dynamic output with less of the low frequency 'breathing' noises and waffle endemic with bass reflex designs. But although well built for the price, the relatively high amplifier power and the light weight of the enclosure (7kg!) means there are obvious residual cabinet-induced colorations, and the box can even be made to jump momentarily given a strong enough input. Indeed, a warning to this effect, and a workaround are included in the instructions.

Sonically, the Tannoy is good for the price, but ultimately it is inevitably a prisoner to its lightweight physical structure. The sound becomes rather tuneless and even a tad boomy as soon as the volume is racked up, and it's limited in its ability primarily to small systems at lowish volume levels.