OTHER TECH

Finally, I turned to the DVD-Audio disc of Vivaldi's Four Seasons and Concertos for Double Orchestra (Naxos). Both types of speaker sounded good with the mild surround ambience in The Four Seasons, conveying the bright reverberation of the small hall, but the dipoles appropriately conveyed a larger ambient sound field.

With two independent string orchestras - one in the front and one in the back - and a violin soloist standing front and center, the Concertos for Double Orchestra were a different story, however. To hear these pieces the way they were recorded, the sound of the orchestra in the back must match the sound of the one in the front. With the monopole setting, the interplay between the orchestras was wonderfully recreated, the individual violinists in each orchestra being clearly audible. In contrast, the dipole setting created a haze of violins in the rear.

However, I guess you could still make a case for dipoles even here. For example, when the rear orchestra plays solo, its ambience is partly recreated by the front speakers - which would suggest using dipoles in front as well. The ideal speaker for this recording would have the properties of both kinds of surround. When I hooked up the M&K S-250s in their Tripole mode, I was quite impressed. By finely adjusting the dipole and monopole output levels, I was able to achieve both a large ambient sound field and fairly precise imaging.

And the Winner Is . . . So which type of surround speaker is better - monopole or dipole? The answer is . . . it depends. Movies tend to sound better over dipoles; the precise imaging of monopoles diminishes the sense of spatial envelopment you want in a home theater. Music with only diffuse information in the surround channels can go either way - any preference will be the result of the recording itself and personal taste, although I tend to prefer dipoles here. But music in which instruments are placed in the surround channels, especially solo instruments, sounds better with monopoles.

Ideally, you'd have a set of monopoles and a set of dipoles, each positioned optimally, and a receiver that lets you switch between them. Almost as good would be a single pair of switchable speakers placed in a compromise position. If you must choose - as most of us do - then take into account your room acoustics, speaker placement, the performance of the speakers you're considering, and your music and movie preferences. While there's no simple resolution to the great surround speaker debate, you'll find that spending a little time thinking about what you prefer to listen to will go a long way toward pointing you in the direction of a solution that's right for you.