"What's this supposed to be? An over-dimensioned megaphon? A blow-drier cap atop a stand? Or better yet, a washing machine slyly disguised as a loudspeaker?" Such counter-praise reactions from my Stereoplay colleagues, upon first eyeing Avantgarde Acoustic's SOLO, prompted my own "Dear Charly!" shock when initially contemplating this 4900 Euro exotic presence in my listening space.

Fact: Gauged by conventional standards, the 46cm diameter, 44cm deep Avantgarde cylinder is a pretty far-out concept not just on visual grounds. The Solo is also the world's first full-range active hornpseaker with a coaxial driver array that's powered over its full bandwidth by an integral 150-watt amplifier.

Motivators for the unusual construction were, among others, request from the US distributor who demanded moderately sized while high-performance horn solutions for surround-sound applications. Even for American home theater or HiFi nuts, existing models in the Avantgarde lineup proved one or two sizes too large. Due to its modest dimensions, the Solo is perfect for center- or rear-channel use. The most elegant solution would be to use five units. Plus a subwoofer. Are you kidding? The Solo by itself dishes out 30Hz bass. Five of 'em and the room shakes.

The twin demands of compact size and high dB levels could only be realized in an active, bass-equalized solution that offers up to 5dB of user-adjustable output balance between HF and LF transducer. Deep bass from a cabinet the Solo's size would have remained impossible otherwise. Another active advantage is the integration of the passive filter with the feedback loop which constantly compares the inverted output against the input signal. Further linearization is obtained with an EQ circuit integral to the amplifier, in practice similar to the LF re-equalization during vinyl playback when its intentional bass-attenuation is inversely compensated for by RIAA.

Stereoplay lab measurements of 113dB peak levels clarified that domestic leases would be cancelled well before the 30cm woofer and 1-inch aluminum tweeter could be overdriven. Both transducers benefit from professional sound reinforcement DNA and are robust enough to render limiter circuits redundant. A high-pass filter allows seamless blending with an external subwoofer, limiting the Solo's lower operating frequencies while increasing ultimate loudness potential. An active subsonic filter prevents overload with excessive low-bass components as are common in blockbuster DVDs.

As regards overloading the Solo, it's one of those questionable audiophile exercises that should require weapons permits. This active coaxial horn exploded with such force in Stereoplay's listening room that witnesses even in the third row suffered involuntary tears. But the Solo does far more than play loud without distortion. Due to its enormous dynamic range and blistering rise times (occasionally reminiscent of pro design), it communicates music with a live charge that makes for a sensual-emotional experience difficult to deny. All along, the baby Avantgarde wasn't agressive but rather, free of distortion and compression and at times even tender.

These usually hard-to-align attributes caused three (nearly) grown men, on a lovely spring day in May, to remain as hypnotized in a windowless room for more than four hours. What the author and two colleagues heard was such a blast that we jointly looked forward to a fun-filled all-nighter.

To describe the particular fun factor of the Solo is difficult. That much is clear - unlike many other speakers, minor weaknesses with these Avantgardes are readily forgiven. Such deficits included a midrange not utterly free of colorations as well as imprecisions in timing and musical flow. Both were confirmed on the test bench (partial resonance in the 2Khz band, moderate impulse response).

Regardless, the even with stands merely 106cm tall Avantgardes cast a soundstage in blatant disregard of their compact dimensions. Such scale usually requires man-sized and very expensive floorstanders.

The Solo's reproduction caused enthusiasm not just for quantitative but rather qualitative performance: Image outlines were enormously precise. Translation? The virtual stage appeared as though cast in stone, without any drift or confusion. Absolutely brilliant was the latest Kruder & Dorfmeister CD, The K&D Sessions: Sound effects, loops and out-of-phase tricks moved with unbelievable precision between the speakers, as though moons circulated around planet on tightly predetermined orbits.

Voices and individual instruments as well locked firmly into position, albeit nearly larger-than-life. Rarely have I been able to stare down as deeply into old warrior Johnny Cash's whiskey-burned gullet [American III Solitary Man, Sony Music]. The Solo's microdynamics were equally compelling, especially guitar sounding particularly tangible and real. How about brass and woodwind? All bets were off with an old 70's BigBand recording [Dieter Reith, My kind of Sunshine, Mojo-Compilation Vol. VI]. When trombones and trumpets let it rip, our testers felt pushed a bit farther against the backwall while beautifully pressurized bass assaulted us with baseball bats. It conjured visions of the entire brass section standing up before their solo and deeply inhaling before blasting off like rocket ships.

The Solo's simple plug'n'plug concept combines the rocking fun of pro speaker with a not utterly coloration-less while still high-fidelity demeanor. But that's not the only justification for this speaker's unique position. It's easily set up and universally adaptable. It plays loud and merely requires a preamp. It simply defines a compact class of its own.

Technical details

The coaxial horn

To realize its goal of point source, Avantgarde mounted the metal tweeter centrally at the woofer's back to radiate through the vented pole piece of the woofer's 4-inch voice coil. Contrary to conventional coaxial designs where the woofer diaphragm becomes the tweeter waveguide to inject unwanted resonances, the Solo tweeter radiates into a small sphercial horn that also doubles as phase plug for the woofer.

Results

Sound (max 70 points): 54
Naturalness: 8
Resolution: 10
Dynamic range: 13
Bass quality: 11
Soundstage: 12
Measurements (max 10 points): 6
Use: (max 10 points): 9
Value (max 10 points): 7

At a glance

Bass-extended active coaxial horn capable of high soundpressure levels. Tonally not entirely even yet extremely agile and with rock-solid projection. The plug'n'play concept's numerous adjustments and focused dispersion creates very non-critical setup. Measurements merely average, fint'n'finish phenomenal.

Stereoplay rating

Sound: Top class, 54 points
Overall score: good to very good, 76 points
Cost/Performance ratio: Outstanding