First Listen: Atlantic Technology AT-1 H-PAS Speakers
I've seen plenty of loudspeaker "breakthroughs" in my half-a-lifetime around the audio sideshow, including speakers shaped like ears, tubas, and croquet balls. And there have also been "revolutionary" new driver designs that resembled stars, chafing dishes, or origami (the Heil Air-Motion Tweeter of the 1970s -in itself quite legit -whose commercial debut was immortally characterized by an audio wag who shall remain nameless as "a marshmallow with a flame-thrower on top").
Yet somehow, even here in the 21st century, serious hi-fi is still delivered overwhelmingly by cones and domes mounted in boxes, be they vented bass-reflex or sealed acoustic suspension cabinets. Why? Because these hoary inventions, well over a half-century old, are still what works best.
So, when Atlantic Technology's Peter Tribeman called to invite me to hear a preproduction sample of a new speaker with an important new enclosure design, I remained - Boston-born though I am - from Missouri (the "show-me" state). On the other hand, I'm well aware that Tribeman, whose boyish face always seems to suggest a bit of P.T. Barnum twinkle, has had a hand in establishing at least four A/V firms (AudioPulse, NAD, Proton, and Atlantic Technology itself), each of which has bowed at least one important, and in some cases game-changing, innovation.
What I found at Atlantic Tech's no-nonsense headquarters just south of Boston was a version of the new AT-1 speaker seen here: an attractive, seemingly ordinary enough mid-sized tower, the speaker configuration most popular amongst serious two-channel listeners. Conventional drivers, conventional crossover, conventional size and shape; the only unusual thing about the AT-1 was the huge rectangular port gaping from the front baffle's bottom.
That is, until Tribeman pressed "play" and the conventional-looking speaker produced deep bass, including bottom-octave orchestral sound to well below 30 Hz, with the power and impact of a well-sited 12-inch subwoofer, or dual-10-inch "power-tower" pair. My jaw may not have visibly dropped, but I was impressed. Fast-forward a few months to today: I have now lived with a production pair of AT-1s for several weeks, and my opinion remains fundamentally unchanged.
The AT-1 tower's plus-sized port is the only external sign of what Tribeman and designer Phil Clements (of Solus/Clements Loudspeakers) have dubbed "H-PAS" (Hybrid Pressure Acceleration System), a new vented-enclosure wrinkle that the team describes as combining elements of acoustic-suspension, bass-reflex, horn, and transmission-line designs. (Hell of a claim, I know, but after conversations with Boaz Shalev, Atlantic Tech's resident H-PAS egghead and computerized finite-element analysis wizard, I understand it well enough -barely - to accept it.) Atlantic asserts that H-PAS extracts more low-frequency acoustic output from a medium-sized woofer's motion - which physics doom to fall off more or less rapidly in every loudspeaker short of garage-sized - than any previous passive, un-equalized design, and without the sensitivity ("efficiency") or distortion penalties of traditional vented, horn, and transmission-line layouts.
And, at least in the AT-1, H-PAS performs as advertised. A bit paradoxically, however, the AT-1's ability to make real bass may not amaze less critical listeners, because plenty of similar-sized speakers produce subjectively impressive bass, usually via an intentional rising frequency response through the 120 Hz-60 Hz octave, before falling off sharply below that point. But it should gobsmack knowledgeable audiophiles.
In my room, Atlantic Tech's modest towers yielded what I judged to be unfettered output to at least 30 Hz. And by "unfettered" I mean flat or damned near so - not -6 or -10 dB (or more) at 30 Hz, which is how every other speaker remotely close to this size would measure.