Worthing-based Bowers and Wilkins is the world market leader in hi-fi loudspeakers.

The company has a huge selection of models, subdivided in numerous different ranges oriented towards specific market niches.

First introduced in 2007, there are four stereo pairs in the 68-series and the Bowers & Wilkins 684 is the latest to come in for our scrutiny. It's the smaller and simpler of two floorstanders and costs £200 less than the larger and more complex 683.

Speaker design

Whereas that larger model is a three-way design, with bass, midrange and treble drive units specifically designed for their duties, the 684 is a two-and-a-half-way design, with two matching 165mm bass/mid drivers.

The lower one is just used to reinforce the bass region, while the upper one covers the complete bass and midrange part of the audio spectrum. Both have cast frames, woven Kevlar cones around 118mm in diameter and fixed central 'bullet' phase compensating plugs.

The bass loading arrangements used here are particularly interesting and unusually flexible. Each of the main drivers operates into its own port-loaded sub-enclosure: the bass-only unit works into the larger sub-enclosure, loaded by a flared front 'flowport'; the uppermost bass/mid driver has the smaller volume sub-enclosure and its reflex 'flowport' is located high up on the rear.

Differences in the sizes of the sub-enclosures and the ports ensure that the reflex port outputs are set at quite different frequencies.

B & W Flexibungs

Furthermore, Bowers and Wilkins supplies two of its 'flexibungs' with each speaker.

These can either be left whole, in order to block a port completely, or their centres can be removed, creating a much smaller diameter foam-lined port which shifts the tuned frequency downward.

If our calculations are correct, the different permutations and combination of bungs and ports allows for some nine possible variations in bass alignment. Some might consider this a potential source of confusion and indecision, but it does at least mean that it should be possible to obtain a good room match.

Solid build

A shiny asymmetric tweeter faceplate, doubling as the maker's name badge, looks a little strange but gives the rather prosaic styling a bit of edge. The diaphragm is a rather exposed and vulnerable-looking 25mm aluminium dome, with no separate grille protection, loaded at its rear by an internal tapering tube.

The whole thing weighs a very substantial 18kg and construction feels very solid and hefty. It looks purposeful enough and the weight indicates you do get plenty for your money. The front panel is textured black, optionally covered by a full-height moulded frame grille, while the rest is finished in vinyl woodprint with a choice of four alternatives: 'cherry', 'light oak', 'black', and the dark brown 'wenge' of our samples.

When we reviewed the 683, no plinth was supplied or available, which not only handicapped the aesthetic appearance, but also made the physical stability very marginal. Since then Bowers & Wilkins has included plinths with both the 683 and 684, which is a significant and worthwhile improvement. The plinth supplied here has rather sharp corners, but does the job well enough, with secure spike accommodation.

Two pairs of terminals enabling bi-wiring are sensibly sited quite close to the floor.

Smooth performance

This 684 might be smaller, simpler and less costly than the 683, but it actually measures rather better, at least under our admittedly rather basic and simplistic regime.

The far-field in-room averaged 'power' response is remarkable impressive, holding within unusually good +/-4dB limits right across the band, from 22hz to above 15khz. The overall smoothness and evenness is only interrupted by a minor peak around 800hz, and another in the extreme treble around 13khz.