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Positive Feedback ISSUE 22
november/december 2005


sp technology

Continuum 2.5 loudspeakers

as reviewed by Victor Chavira







Marten Design Miles II (primary system) and B&W DM 302 (secondary system).

Magnum Dynalab MD-208 receiver (primary system) and Troll integrated (secondary system).

Phillips DVD-963SA player, Apple Mini-Mac, and a LINN Axiss turntable with the Adikt cartridge.

Nordost Quattro-Fil interconnects, Analysis Plus Oval 9 speaker cables, and El Dorado power cords (primary system). JPS Ultraconductor speaker cable, Nordost Blue Heaven interconnect (secondary system).

Audio Magic Stealth Power Purifier, Vibrapods, Townshend 3D sink Table), and Echo Busters (primary system). Monster Cable HTS1000 power center (secondary system).


SP Technology, based in Indiana, is a small loudspeaker company with big aspirations. Judging from their Continuum 2.5s, SP Tech is well on its way to achieving its goals. The Continuum 2.5s are large, floor-standing speakers in the middle of a product range that also includes the two-way Timepiece 2.1 stand-mounted speakers and the top-of-the-line Revelations. The SP Tech designers have extensive experience in the fields of sound reinforcement and cabinetry. As a result, the C2.5s exhibit a high level of fit and finish. Like all SP Tech loudspeakers, the 2.5s are available in a variety of finishes and internal upgrades.

For a detailed technical description of the 2.5s, visit the SP Tech website (, but I will briefly describe their essential features. The first is the finely finished matching "stand," which is actually an integral part of the speaker. Underneath the speaker is a wide, rectangular cavity that opens into the top of the hollow base, essentially doubling the speaker’s internal volume. Speaker and stand lock tightly together to form a sturdy column.

The second notable feature is the "horn-mounted," one-inch soft dome tweeter. Technically, the concave flare is too shallow to be a true horn, and SP Tech calls it a waveguide. The waveguide provides a wide dispersion pattern without the colorations associated with horns. My listening confirmed a larger-than-average sweet spot that remained constant whether I was sitting or standing. The waveguide is carved directly into the three-inch-thick baffle and finished in layers of high-gloss black lacquer.

An unseen feature of the C2.5 is the incredibly low crossover point of 600Hz. According to SP Tech, the waveguide increases the acoustical loading of the tweeter at the lower frequency of the driver’s operating range, where high efficiency matters most. As a result, SP Tech claims that the usual phase, timing, and crossover distortions are virtually eliminated. Two eight-inch aluminum woofers handle the frequencies below the crossover point.

The speakers were set up with the assistance of Mike Garner, proprietor of and SP Tech’s West Coast dealer. Mike placed the 2.5s in roughly the same spots as my Marten Miles, the only difference being a very small toe-in. After listening and fine tuning, Mike was satisfied with the sound.

My first impression of the Continuum 2.5s was very positive. I played an LP of The Planets with Zubin Mehta and the Los Angeles Philharmonic, and was deeply impressed by the 2.5s’ superb soundstage. The front wall vanished, and music seemed to emanate from way behind the plane of the speakers. The size and shape of the orchestra was projected with striking realism. Dynamic impact was also excellent, with sound building to a room-shaking climax at the end of "Mars, the Bringer of War."

When I listened to El Cantante, by Argentinian artist Andres Calamaro, I noted the SP Techs’ exceptional retrieval of ambient musical clues and details. I could effortlessly distinguish shakers from gentle brushes on a snare. The singer’s vocal inflections were rendered with lifelike shadings and air. The music unfolded with true dimensionality, and in real time and space. The soundstage was exemplary—the corners of the space in which the musicians played were not limited by the corners of my room.

When I listened to a live recording by blues/rock/jam band Goverment Mule, the music again seemed to originate from about five to ten feet behind the plane of the speakers, as if I were in the place where the recording was made. The space between the audience and the musicians on the stage was authentically recreated. Even the occasional shout from an audience member was captivating. I had no idea that my front end was capable of such fine resolution. The performance was rocking, bluesy, sweaty, and soulful. The SP Tech 2.5s drew high marks for their ability to convey raw emotion and power.

Switching back LP, I listened to "Scarlet Begonias," from the Grateful Dead’s 1974 release, Mars Hotel. The song’s reggae rhythm is accented by a harpsichord, and the action, keys, strings, and soundboard of that instrument grabbed my attention like the flowered woman in the song, who stops men in their tracks with her rare beauty. The song also features a pipe organ, which was evidently recorded in a much larger space than the other instruments. The musical details happened quickly, but were so richly displayed that they draw me into the music and greatly enhanced my enjoyment. 

Continuing with harpsicord, I listened to an LP of Trevor Pinnock and the English Concert playing the Brandenburg Concerto No. 6 by J.S. Bach. Despite their size, I hardly noticed the SP Techs while the music was playing. These speakers simply do not sound like typical two-ways. Instruments sound whole, not like they are reconstituted form high and low frequencies. I could detect no timing distortions whatsoever. Pitch relationships were uncorrrupted by an intrusive crossover. The English Concert appeared before me, and music filled the room.

The last disc I played was a DVD featuring Alfred Brendel performing Schubert’s Impromptu No. 3 in G Flat. Brendel sits before the majestic instrument under a single spotlight on a darkened stage. His left hand begins the recurring arpeggios, then his right hand gently taps out the serene melody. I not only heard a passionately played grand piano, but felt its vibrant presence in my body and soul.

I immensely enjoyed my time with the SP Tech Continuum 2.5 loudspeakers. They do not call attention to themselves with commanding bandwidth or ruthless resolution, as do some speakers in their high-stakes price range. Many customers shopping in this segment of the market want something flashy, and the SP Techs are not for them. Rather, they are for people who know the sound of real music, in real time and space. My $10,000 Marten Miles speakers are more extended and dynamic, but do not have the phase and timing perfection that allows the SP Techs to seamlessly and realistically recreate musical events. The SP Tech Continuum 2.5s may be difficult to find, but they will unquestionably be worth the effort. Victor Chavira

  • Frequency Response: 25Hz - 24kHz +/- 2dB (typically +/- 1dB) -3dB @ 25Hz & 30kHz

  • Phase response: Less than 360° from 100Hz - 20kHz

  • Group Delay Response: Less than 1 mS delay shift from 100Hz - 20kHz

  • Directivity: 90° Horizontal x 30° Vertical from 900Hz - 10kHz.

  • Peak Power Handling: Greater than 1000 watts (10mS)

  • Short Term Power Handling: 600 watts (I.E.C. 268-5)

  • Long Term Handling: 250 watts (I.E.C. 268-5)

  • Sensitivity: 91dB SPL @ 2.83V /1-Meter, 88dB SPL @ 1-watt/1-Meter

  • Impedance: 4-ohms (nominal) - 3.2-ohms (minimum)

  • Crossover: 4th order symmetrical, in phase Linkwitz-Riley @ 750Hz.

  • Power Requirements: 50 watts RMS/Channel (200 - 750 WRMS/Ch. preferred)

  • Horizontal Dispersion: +/- 45° - 600Hz to beyond 10kHz (standard -6dB Beamwidth Limits)

  • Vertical Dispersion: +/- 15° - 600Hz to beyond 10kHz
    (standard -6dB Beamwidth Limits)

  • Low Frequency Driver: (2) - 8" Aluminum Cones w/Phase Plug & Cast Magnesium Frame

  • High Frequency Driver: Waveguide Loaded 1" Textile Dome - Ferrofluid Cooled

  • Dimensions: 53.75" (136.5 cm.) H X 12.5" (31.7 cm.) W X
    15.75" (40.0 cm.) D

  • Weight: 150 lbs. (65.2 kgs.)

Continuum 2.5 loudspeakers
Retail: $5995 a pair

SP Technologies
web address: