Bowers & Wilkins 684 review

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.

Under our room conditions the bottom end worked very well with both ports unobstructed and the speakers sited well clear of walls. Sensitivity is a quite generous 90dB, especially since the bass is well extended (-6dB @ 22hz in-room) and the easy-to-drive impedance stays above 6ohms through most of the band (dipping marginally below this above 10khz).

Pair matching is satisfactory enough, albeit with minor variations at low frequencies and the impedance also shows a minor 'glitch' at 950hz. The front port is tuned to 37hz (28hz with foam lining), while the rear port is tuned to 68hz (50hz when lined).

Lack of energy

As predicted by the in-room responses, the 684 delivers an impressively neutral and even-handed sound that's thoroughly competent in nearly every respect, even though it does reflect its modest price
and aspirations to some extent.

Interestingly, the mild lack of presence energy that seems to be a regular feature of most Bowers & Wilkins designs is virtually absent on this occasion and in this respect the 684 has an attractive openness that is not shared by many of its stablemates.

Rather less happy is the top end, which sounds a little too obvious and slightly congested, especially as it doesn't have the sweetest character through this part of the band. Whether that mild hardness at the top end is related to the upper treble peak which showed up on the room measurements is hard to say; it's also curious to note that the same peak was much less obvious in the 683 model, which shares the same tweeter.

Budget limitations

That combination of an open presence and slightly coarse top end means that the 684 sounds happiest when operating at modest levels, which suits its fundamentally open neutrality particularly well.

Start winding up the volume and although the speaker hangs together very well, delivering a powerful bottom end foundation, the mid and top moves progressively out of its comfort zone and starts to sound harder and more edgy, betraying the inevitably compromised ingredients of a budget speaker.

The dynamic performance – specifically the limitations thereof – is the other factor that constrains the performance of this speaker. While dynamic range per se is satisfactory enough, there is clear room for improvement – subtle low-level detail, such as the fine texture of orchestral instruments, tend to be masked.

Fair price

Stereo images focus well laterally, but depth perspectives are somewhat limited and ambient information isn't very well resolved. Furthermore there's also a clear lack of overall dynamic tension. Again this is quite normal for a speaker of this type, but remains a limitation nonetheless.

The above criticisms should not be taken as harsh. When its reasonable price is taken into account, the B&W 684 is actually a very good loudspeaker delivering a fine all round performance with an unusually smooth and neutral overall tonal balance.