Definitive Technology Bipolar BP-8040ST 5.1-Channel Speaker System (TPV 108)

Bipolar Design Gives Huge Soundscapes

CS-8040HD center channel speaker, technical highlights:

• Driver complement: one 1-inch aluminum dome tweeter, two 4.5-inch BDSS mid/bass drivers, and one oblong, upward-firing 5-inch x 10-inch passive radiator, which is said to increase bass extension.

SR-8040BP surround/FX speaker, technical highlights:

• Bipolar driver array: two 1-inch aluminum dome tweeter, two 3.5-inch BDSS mid/bass drivers.
• The SR-8040BP feature an angled, almost V-shaped face that provides proper mounting surfaces for the bipolar driver array, with one half of the array angled forward and the other half angled backward.

SONIC CHARACTER

The BP-8040ST system’s overall sound takes its cues from the voicing of the BP-8040ST super towers, while offering an excellent degree of voice matching from channel to channel within the system.

The sound of the BP-8040ST centers on a midrange that offers a good combination of openness, natural warmth, and surprisingly full-bodied dynamics—qualities that in a very real sense are mirrored by the rest of the speaker system. The midrange array offers good measures of transparency and detail, but its greatest strength may be dispersion and an ability to set midrange frequencies free from the confines of the super tower cabinets. It is aided in this effort by the rear-firing bipolar array, which adds significant width, depth, and balance to the overall presentation.

The aluminum dome tweeter gives unexpectedly smooth and decidedly non-metallic-sounding highs, and it integrates very well with the BDSS mid/bass driver. But with that said, let me add that the tweeter does not seem to me to offer quite the last word in treble transient speed or detail, so that in comparison to some tweeters I’ve heard it does seem to leave small bits and pieces of treble information “on the table,” so to speak. But while the tweeter may leave detail mavens wishing for a bit more, the good news is that its inherent smoothness enables the speaker to work well even with material that might make some competing speakers sound “hard” or “edgy” by comparison.

The woofer system of the BP-8040ST is terrifically well conceived and is a fine performer. If you’re in the habit of setting your performance expectations by visually gauging the volume of the speaker enclosure, then I can pretty much guarantee that the BP-8040ST will blow your mind, because this relatively compact speaker offers bass output that is both vigorous and that offers serious low-frequency extension. Even in moderately large rooms, the BP-8040ST’s had no trouble at all in handling large-scale low-frequency sound effects without apparent distress (well, except for others in the house who might be put off by thunderous sounds emanating from the living room). Credit for the 8040ST’s low frequency clout must go in large part to the speaker’s clever amplifier design, which is capable of selectively applying momentary compression on select frequency bands in real-time, while leaving other frequency bands untouched.

The BP-8040ST’s bass is slightly, but only slightly, more warmly voiced than the bass you might hear from, say, Definitive’s excellent Mythos ST or STS speakers. I suppose this might be attributable to the fact that the BP models use cabinets made of MDF, while the Mythos models use exceptionally rigid extruded aluminum enclosures. In a strict, textbook sense (and in a pursed lips, furrowed brows, “let’s concentrate like crazy on what we’re hearing” audiophile sense), the Mythos approach to bass is arguably more accurate, but my sense is that a great many listeners will actually prefer the BP’s bass because it sounds more immediately hearty, powerful and accessible.

Just for the record, let me add that the CS-8040HD is a real corker of a center channel, too, in that it A) matches the voicing of the super towers well, and B) provides—as do the super towers—a sense of effortless, free-flowing dynamics. In theory you could probably overload the center if you really pushed things to the limit, but this would likely occur at volume levels most households would find intolerable in the first place.

Finally, the SR-8040ST’s do what you would want any good surround speaker to do, which is to convey surround channel information without drawing much if any attention to themselves, and without messing up the voicing of the rest of the system.