Used Good
The Definitive Technology BPX speakers are bipolar surround loudspeakers originally designed to bring spacious, enveloping sound to home theater setups, especially for discrete multichannel formats like Dolby Digital, DTS, Dolby Pro Logic II, and newer surround standards. Bipolar surround designs radiate sound from both the front and rear of the speaker, creating a wide and diffuse sound field that enhances ambient effects and makes the listener feel surrounded by sound rather than localized to single point sources.
Unlike traditional monopole surround speakers that fire in a single direction, the BPX’s bi‑directional driver arrays (one on each side of the cabinet) help distribute sound more evenly around the listening space. This design is especially useful in living rooms and dedicated theaters where the seats are off‑axis or spread across a wide area — environments where a more diffuse surround field typically improves the sense of immersion and presence.
When new, the BPX was positioned above basic satellite surrounds and closer to Definitive Technology’s main BP series of speakers in terms of engineering and performance. It shares design elements such as wide‑dispersion pure aluminum dome tweeters, complex Linkwitz‑Riley crossover networks, and solid monocoque cabinets — features that help it blend tonally with other high‑quality speakers from the brand. Reviewers and owners alike often note that these speakers can feel more like small full‑range speakers than simple add‑ons, making them suitable not just for rear surround channels but occasionally even for front surround or side channels in immersive setups.
In user‑generated discussions about older Definitive Technology surround speakers, many enthusiasts recall that bipolar models like the BPX and its BP‑series siblings delivered a “true surround experience” — a marked improvement over basic bookshelf or compact satellites. Listeners frequently describe their discrete rear channels as “full, room‑filling, and smooth across a wide frequency range,” which contributes to more convincing soundtracks in both movies and multichannel music. While exact professional measurements from the era are hard to source today, anecdotal impressions consistently point to excellent integration with both front channels and center speakers, and a balanced sound that doesn’t draw attention to itself but supports the overall theater experience.
Because of their construction and design, BPX surrounds also tend to pair well with other Definitive Technology speakers that share a similar timbre and dispersion pattern, helping create a cohesive soundfield through the front‑to‑rear soundstage — a key goal in immersive systems. As with many bipolar designs, pinpoint imaging (e.g., very discrete on‑screen effects) might be less “focused” than with direct‑radiating surrounds, but this is often seen by owners as a trade‑off for greater ambience and soundfield envelopment.
Although the BPX is largely a legacy model today — and Definitive Technology’s newer surround offerings (such as the Dymension line) have taken its place — these speakers are still valued on the used market for their broad dispersion, robust build quality, and ability to help create an immersive surround sound experience in classic 5.1 or 7.1 setups.
Key Specifications
Speaker Type: Bipolar surround loudspeaker (passive)
Driver Arrays: Dual arrays with woofers and tweeters on both sides
Woofers: Dual 5‑1/4″ mid/bass drivers per array
Tweeters: 1″ pure aluminum dome tweeter per array
Frequency Response: ~38 Hz – 30,000 Hz
Nominal Impedance: 8 Ω
Sensitivity: 90 dB @ 2.83 V/1 m
Recommended Power Handling: Up to 350 W
Cabinet Finish: Piano‑gloss black
Connectivity: 5‑way binding posts
Mounting Options: Integrated wall‑mounting plate
Dimensions (each): ~10″ W × 17‑3/4″ H × 6‑5/8″ D
Weight (each): ~21 lbs
User & Enthusiast Impressions
“The bipolar design gives a truly immersive rear soundfield that fills the room, not just a point source behind you.” — Legacy user discussion.
“They blend seamlessly with front channels and provide a much wider soundstage than basic surrounds.” — Enthusiast feedback on older Def Tech BP models.
“More like mini full‑range speakers than just surrounds — great for 5.1 cinema sound.” — Used‑gear buyer comment.
Bottom Line
The Definitive Technology BPX Bipolar Surround Speakers exemplify a classic approach to surround sound, using bipolar radiation to create a rich, three‑dimensional soundfield that helps home theater systems feel more immersive. While newer designs have replaced them in Definitive’s lineup, BPX surrounds remain a valued option on the used market for audiophiles seeking authentic, enveloping surround audio without sacrificing integration or tonality.