All of the good things that you expect from a horn loudspeaker are there: the far-truer-to-life (and faithful-to-the-source) dynamic range; the fine low-level detail about instruments and performance; the superior speed of attack; the lifelike presence on voice and instruments. What aren’t there to any appreciable degree are the bad things that you also expect from a horn loudspeaker: the lack of driver-to-driver coherence, the poor-to-nonexistent integration of the woofer or sub, the “horn-colored” midrange and/or piercingly directional tweeter, the six-foot-wide imaging, and (to a degree) the truncated soundstaging. Here, for the one and only time in my experience, is a horn system that, minus an occasional dollop of extra sibilance (not brightness, mind you), does disappear as a sound source.
Let’s start with timbre and dynamic range—perhaps the foremost of horn-loudspeaker virtues but often the very things that get them into the most trouble. Most horns are not particular “neutral” transducers. Because of their own colorations and the often highly-colored amplifiers that are used to drive them, they don’t produce timbre with the transparent-to-source accuracy of a linear system like, oh, a typical Magico Q Series floorstander. What horns (and SETs) do do, or can do, despite their colorations is make timbre sound spectacularly lush and beautiful—the way we would like tone colors to sound at their best rather than the way they more often sound in life or were actually recorded on record. In short, when it comes to timbre horns are the quintessential “as you like it” kind of speaker.
Where horns are highly transparent-to-sources, however, is dynamic range. Here no other kind of speaker will reproduce swings from pianissimo to fortissimo (or the absence of them on highly compressed pop records) with the accuracy of a horn. A recording with considerable dynamic range—even a smaller-scale one such as Mario Lanza Live in London [RCA], for example— can give conventional loudspeakers fits. At shows I’ve almost invariably heard such speakers grow bright and edgy or outright break up on Lanza’s most powerful fortes, provoking at least one famous audio engineer/loudspeaker designer to proclaim that there had to be something “wrong” with this record (as his speakers were, presumably, perfect). There was and is, in fact, nothing wrong with the recording. It’s just that when playback ranges, at an average level of a mere 62.7dBC, from a peak of 90.5dBC to a minim of 37.3dBC (actual measurements taken using the Avantgarde Zero 1s with a calibrated SPL meter) most drivers simply don’t have the “bandwidth” to cope at more lifelike average volumes. Their inertia, their peak-to-peak excursion limits, their distortion when they are pushed hard quickly—all of the things that don’t come into play with a horn-loaded driver—make a simple aria like “Lamento di Federico” a torture test par excellence.
Horns sail through such demanding dynamic passages with literal ease, waxing and waning continuously, as dynamics do in real life, rather than flattening out and breaking up on peaks or dropping below the noise floor on valleys as they do with many conventional loudspeakers. But what horns will also do (as already noted) is amplify their own resonances along with the music, giving something like Lanza’s tenor a markedly nasal, cupped-hands timbre and (if the tweeter is also misbehaving—and it usually is) added sibilance and overly aggressive, in-your-face presence. When you factor in a typical horn’s inability to image precisely, you can end up with just as much of a sonic nightmare as you get from a conventional cone or planar loudspeaker in the face of virtually instantaneous, near-60dB dynamic swings.
The Avantgardes do none of these bad things and all of the good ones. Thanks to Thomas Holm’s brilliantly successful DSP’ing of amplitude response, the Zero 1s are far and away the most neutral—which is to say, the least “horn-colored”—horn loudspeaker I’ve ever heard. By neutral, I do not mean the Zero 1s are lacking in color—overly cool, clinical, or whitish. They have extremely lifelike timbre on well-recorded discs; they simply aren’t anywhere near as Technicolored as most horn speakers. As a result, when Lanza hits his triple-fortes there is not only no strain; there is also no added distortion, horn coloration, or excessive in-your-face/lap presence (although the Zero 1s do have more presence than non-horn-loaded speakers).
In addition to vanquishing the coloration/distortion problem, Holm’s DSP’ing makes the drivers work in phase and time to a degree I’ve never heard before from a horn loudspeaker. The most obvious audible benefits come in imaging and soundstaging. On a CD like the Lanza disc or a 96/24 file like Joni Mitchell’s Court and Spark [Warner/Asylum] or an LP like Leonard Cohen: Live in London [Sony], Lanza’s and Joni’s and Lenny’s voices (and the voices of the backup singers on the two pop albums) have as much focus as you’d hear on a good ’stat. They’re not etched or laser-cut, as with certain mini-monitors, but they are definitely naturally sized and defined.
The DSP seems to pay a similar benefit with the soundstage, which extends slightly outside and behind the speaker enclosures, though it typically starts closer to the plane of the drivers or a bit in front of it. (I have to wonder whether this somewhat wider, deeper, “outside the box” staging—so unusual in a horn speaker—isn’t also a side benefit of the way the horns are built into the Zero 1’s enclosure. Unlike horns that extend outward from the front baffle, the Zero 1’s concave horns are surrounded by a bit of a flange—the “left-over” surface-area of the rectangular baffle into which they are set. Perhaps this flange gives them a touch of point-source-like dispersion. I’m sure its presence was factored into the DSP.)
With such a clean, focused, and spacious presentation— and such superior dynamic range—the Zero 1s have excellent resolution, reproducing little details, such as the swirl of drummer Paul Motian’s brushes on the skin of his snare or the way the great bassist Scott LaFaro double-stops certain plucked notes on Waltz for Debby, or the chucking sound of Javier Mas’ archilaud (a Spanish version of the twelve-string guitar) in “Ain’t No Cure For Love” and other numbers from Leonard Cohen: Live in London, with lifelike clarity and color. When speakers are this neutral and drivers are this low in inertia, you’re not going to miss many musical or performance details. On the other hand you’re not going to be buried in them, either—this is not an analytical speaker.
I mentioned Scott LaFaro’s standup bass just a sentence ago, so let me turn to the Zero 1’s bottom octaves. The seamless integration of a cone woofer into a system of horn-loaded drivers is really one of the great triumphs of this loudspeaker (and of Holm’s DSP). In timbre, focus, speed of at-tack, and resolution, you will have no sense—zero—that the music in the bass octaves is coming from a different kind of driver. In dynamic range and impact, the woofer also keeps up with the horns convincingly, although I wouldn’t say the Zero 1’s single 12" woofer packs all the weight and wallop of the four ported woofers in a multi-driver floorstander like the Raidho D-5; on the other hand the Zero 1 doesn’t have the excess midbass energy or the beguiling and, I think, lifelike added power-range warmth of the D-5. (Unlike the Raidho, the Avantgarde was a snap to situate in my treated listening room and didn’t excite any room resonances.) The Zero 1’s bass is extremely detailed, exceptionally well defined, surprisingly deep-reaching, unusually natural in timbre, but perhaps somewhat laid-back when it comes to slam.
No one should take this last point as a potential disqualifier. There really isn’t anything “disqualifying” about this landmark horn-loaded speaker—the first of its breed and, as I’ve already said, the highest-fidelity compact horn system I’ve ever heard. The Zero 1 does have a touch more presence (a more forward-projected midrange—although see my sidebar on setup for a change in this regard) than some cone speakers or most ’stats, and it can on rare occasions (I mean rare—it doesn’t do this on anything like a regular basis) very slightly accentuate sibilance on vocals (once again see the sidebar on setup), but on the whole its horn-loaded tweeter is as much a model of good behavior as its midrange and its woofer, sounding sweet, clear, and natural on massed strings, woodwinds, upper-octave piano (and other percussion), and higher-pitched brass. (Though its horn virtues are manifest, it is only fair to point out that—perhaps because of the equalization and the absence of true compression drivers— the Zero 1 isn’t as lightning-fast or as hard-hitting as a “true” horn speaker, though the way Holm’s eq eliminates horn issues more than makes up for these very small differences in speed and impact.)
Let me conclude with an overall observation. I am an analog guy used to listening to analog sources via conventional electronics, and the Avantgarde Acoustic Zero 1 is a digital loudspeaker. Consequently, you might think that I would’ve found its sound not to my taste. However, while I can’t truthfully say that listening to digital and digitized sources through a digitally optimized loudspeaker is the same experience as listening to analog sources through conventional loudspeakers and electronics, I can say this: I was not at all put off by the quality of the Zero 1s’ presentation. On the contrary, I greatly enjoyed (and continue to enjoy) the Zeros, to such an extent that I’m seriously considering buying them—not that I think (or think that you should think) that a reviewer buying any item at parts-cost should be considered a virtuous act. What I do think is that when a guy who is as devoted to analog as I am (and continue to be) finds a digitally optimized speaker so engaging and pleasurable—and, on many occasions, so startlingly realistic it curls his toes (give a listen to Nina Simone and tell me she isn’t “right there”)—that he’s considering buying them, it does mean something. To put this plainly, if you’re looking for the benefits of horns without their downside and you use digital sources almost exclusively, I can’t recommend the Avantgarde Acoustic Zero 1 active, horn-loaded, digitally-optimized, virtual plug ’n’ play loudspeaker highly enough.