Atlantic Technology says the AT-1s use a breakthrough acoustic technology that allows speaker designers to achieve targeted bass performance with smaller drivers, smaller cabinets and lower cost. Called ‘H-PAS’, it’s in the company’s AT-1.

After first demonstrating its ‘Hybrid Pressure Acceleration System’ (H-PAS™) speaker technology in 2009 (at CEDIA), US company Atlantic Technology followed up by releasing its AT-1 loudspeakers at the Las Vegas Consumer Electronics Show in January 2010. The CES press release announcing the speakers boasted: ‘H-PAS is a breakthrough acoustic technology that allows speaker designers to achieve targeted bass performance with 50 per cent smaller cabinets, smaller drivers, and lower costs.’ Well, the AT-1 speakers have finally arrived in Australia, and Claver Harper, from local distributor Network Audio Visual, was quick off the mark to send us one of the first pairs for review.

Atlantic-AT-1 LoudspeakersThe Equipment

Having read the press release prior to the speakers arriving, I was a little surprised when they did arrive, because the two cardboard shipping boxes were hardly what I’d call ‘small’! And, when I’d finally unpacked the speakers, screwed on their outrigger feet and conical ‘spikes’, and stood them upright in my listening room, they still weren’t exactly small… though to give them their due, they were the smallest of five pairs of floor-standers currently in the process of being reviewed. In fact, the AT-1 cabinet is 1,041mm high, 227mm wide and 348 mm deep. Given these external dimensions, and the fact that the cabinet is mostly constructed from 19mm MDF, my ‘back of the envelope’ calculation put the internal volume of the AT-1 cabinet at 89-litres, or almost double the 1.6 cubic feet (50-litres) claimed by Atlantic Technology.

However, I think I would have been disappointed if the cabinets had been smaller, because their impressive size means there’s more to admire in the curved side walls, which are finished in a superb, high-gloss ‘metal-flake’ black lacquer paint, the artfully-curved (and magnetically attached) punched black metal speaker grilles, the outwardly curved lower section of the front baffle and the classy glass top plates that finish off the speakers. Make no mistake; Atlantic Technology’s AT-1s are very, very good-looking loudspeakers!

Detaching the metal grilles reveals the driver complement, which is a pair of 133mm (nominal) diameter bass/midrange drivers, mounted above and below a single 28mm tweeter in classic MTM geometry. The bass/midrange drivers are identical, with cones made from graphite-loaded homopolymer (GLH). At the centre of each cone is a black, stiffened fabric dustcap with a conventional ‘dome’ profile, while at the periphery there’s a rubber suspension, again with a conventional profile. Atlantic Technology rates the diameter of these bass/midrange drivers at 133mm. Despite appearances, the driver chassis itself not circular, so my measurements of it returned an overall dimension of 150mm (widest) and 133mm (narrowest), with a mounting hole figure of 139mm and a Thiele/Small diameter of 109mm. This last (most important!) dimension puts the Sd at 94cm² per driver, or 188cm² for the system, meaning that if Atlantic Technology had used just a single driver to deliver bass, instead of two, its ‘nominal’ diameter would have to have been in the order of 170mm to displace the same amount of air. The driver chassis is made from pressed steel and supports a standard-sized, non-vented magnet that’s 28mm deep and 88m in diameter. The design of the soft parts is conventional, with the volume of air underneath the spider being unvented. The drivers are attached to the baffle using cross-head bolts and captive threaded retainers, so they can be easily removed.

The tweeter is rather unusual. It has a 25mm soft dome at its centre, with an ‘over-sized’ long-throw surround that increases the diameter of the moving part to 40mm. All this is driven by a voice coil powered by a small neodymium magnet that’s equipped with a ‘crown-shaped’ heat-sink that not only dissipates heat from the magnet to reduce dynamic compression effects and increase power-handling capacity, but also acts as a back-chamber for the dome. The tweeter sits in a very shallow horn to increase its efficiency and control its directivity.

At the base of the front baffle is a very large, rectangular vent measuring 120×90mm. I couldn’t measure the depth of the port because my tape measure was impeded at a depth of 220mm by a silver metal mesh grille, presumably to prevent small pests (mice and suchlike) from making a home inside the speakers, nestled in the comfy fluffy white acoustic material, alongside the nice warm magnets! I often castigate manufacturers for not blocking off large vents in this way, so I was genuinely pleased that Atlantic Technology has done so.

Around the rear of the speakers is the speaker terminal plate, which sports ‘HF’ and ‘LF’ pairs of multi-way gold-plated speaker terminals, bridged by gold-plated buss bars. Above these is a small, three-position toggle switch, with the positions marked ‘+’, ‘0’ and ‘–’. As you’ve probably guessed, this switch allows you to alter the output of the tweeter relative to the bass/midrange drivers. The manual says: ‘This control changes the relative output level of the tweeter. It has been designed to hep compensate for different room acoustics and personal listening preferences. The ‘0’ position is the most “accurate” frequency response, but that does not mean that it is necessarily the “recommended” position.’

I was a little surprised to find that the serial numbers on the pair of speakers I was supplied for review were not contiguous, and that there were not one, but two serial numbers per speaker, the second set being on a hologram sticker. Steve Feinstein, Atlantic Technology’s Director of Marketing and Product Development, told me not to worry about the non-consecutive serial numbers, saying: ‘They are not matched pairs—our QC is good enough that they don’t have to be!’ He also told me that the hologram label was an internal tracking number for the number of H-PAS products Atlantic Technology had shipped and had no relevance to the end user. However, I also wondered whether it was a countermeasure against counterfeiting, given that Atlantic Technology’s website warns under the heading ‘Counterfeit Product Alert’: ‘We have reason to suspect that an internet storefront is listing counterfeit Atlantic Technology products for sale which purport to carry the Atlantic Technology logo and trademark. Counterfeit products are not built with genuine Atlantic Technology parts. They do not conform to our specifications or quality standards, and carry no warranty.’ The company then supplies a list of approved internet sites for sales of Atlantic Technology products, one of which, Outlaw Audio, has the exclusive internet sales agency for H-PAS products.

The AT-1’s crossover network is split over two separate printed circuit boards (PCBs). The high-pass filter section is attached to the rear of the rear terminal plate, in the usual manner, and comprises a three-position switch, a pair of MPT ‘Yellow’ capacitors, a pair of Dayton ‘Audio Grade’ MPT capacitors, seven 10W cermet resistors, and three inductors, two of which are ferrite-cored and sit parallel with each other, and one of which is air-cored and properly cross-mounted on the PCB. The PCB for the low-pass filter section is mounted high up on the inside of the enclosure, and comprises a single iron-cored inductor, two 10W cermet resistors, one MPX capacitor and one MPT ‘Yellow’ capacitor bypassed by a 12µF 100V bipolar electrolytic. According to Atlantic Technology, the topology of the circuit controlling the bass drivers is not a ‘low pass’ filter as such, but is more properly characterised as a ‘tank/trap’ circuit and results in a nominal crossover frequency of 2kHz. Internal wiring is via individual strands of 16AWG cable, soldered to the PCBs but attached to the drivers via spade-lugs.

Atlantic Technology AT-1 Loudspeakers

In Use and Listening Sessions

When I finally got around to firing up Atlantic Technology’s AT-1 speakers, I was as impressed by their sound as I was by their appearance. My immediate impression was of a lively, dynamic loudspeaker system with a flat, well-balanced and nicely extended frequency response and that’s the impression that stayed with me not only throughout my listening sessions, but also after I’d put the speakers away for a few weeks, then re-connected them for a ‘reprise’ audition, to make absolutely certain that my first impressions were accurate.

Despite all Atlantic Technology’s predictions that I’d be most impressed by the bass, I have to confess that what most impressed me about the sound of the AT-1 speakers was the clarity and articulation of the midrange, and the almost holographic sound-stage of the imaging—at least horizontally, the stage depth wasn’t quite at this same extraordinarily high level. There is one caveat to this sound-staging, which is that like all MTM driver arrays, it’s absolutely critical that your ears are on-axis with the tweeters, and that you’re in the far field… so if your listening position is necessarily closer than about two metres, you just won’t get the full effect. I was transfixed by how the AT-1s reproduced ‘Home’, an album released by Emma Gilmartin and Tony Gould. It’s recorded clean and plain, and the songs are unashamedly sentimental, but it’s all good, because with just Emma’s unadorned voice (sometimes a cappella) and Gould’s lone grand, it’s incredibly revealing of a loudspeaker’s deficiencies, and none at all were audible when I used it to audition the AT-1s. (Gilmartin’s voice is these days unusual because she uses almost no vibrato.) The bonus is that if you have small children, they’ll probably love going to sleep to some of the songs on this CD (Rainbow Connection, You Are My Sunshine, Que Sera Sera, Homeward Bound). There’s also a lovely version of Janis Ian’s Jesse in which Emma shows off her insanely accurate ability to perfectly pitch any note, even when it’s a deliberate discord (actually, she demonstrates this right throughout this album, but she sings some of my favourite ‘impossible’ intervals on this track and nails them without so much as a micro-slide onto the note.)

High frequencies were accurately portrayed, so that the harmonics were correctly structured, but the sound was pleasantly ‘rounded’ which I initially put down to the use of a soft fabric dome, rather than a metallic one. However, in the end I decided that it was more likely that I was hearing a very slight attenuation of the extreme highs—not enough to lose the lovely ‘air’ around the high frequencies that was always apparent, but just enough to give that rounded sound. Then I remembered that I had completely forgotten about the tweeter level switches and when I checked, both were in the –1dB position. A few hours of playing with various settings revealed that I was happiest with the 0dB setting, though on some CDs +1dB was definitely the go. I would, however, rule out the –1dB setting entirely unless your room is supremely acoustically bright!

Bass response was very good, with various of my deep bass CDs proving that it extended down to at least 31Hz at almost reference level. However, my CD of single piano notes showed that B0 (30.8Hz) is really as low as it goes, because the A# underneath it was ‘way lower in level, and then the A natural even lower in level again. However, although bass extension was excellent, and the detailing of solo bass lines was outstanding, I found the ‘impact’ level of the transient bass notes—while it was OK at lower listening levels—was somewhat less satisfying at higher sound pressure levels, and most noticeably if there was also a dense layer of additional musical information going on at the same time, particularly at low frequencies, but also in the upper bass and lower midrange. In practical terms, this mostly meant that it was only large-scale orchestral works that had me reducing the volume to retain clarity and balance but, though rarely, it also sometimes arose with jazz and rock CDs. And although the AT-1s can certainly be played loud—very loud, in fact!—sustained high-volume operation saw some loss in dynamics after a few hours.


After hearing the AT-1s at CES, Stereophile Editor John Atkinson told Peter Tribeman, who was demoing them, that if he could get them onto the North American market at less than US$2,500/pair, he’d ‘have a hit on your hands.’ As it happens, Tribeman did manage to get them onto the US market at less than that price (a greenback less, to be specific). Here in Australia, their recommended retail price sees them competing head-to-head with a large number of similarly-sized, equally highly-credentialed floor-standing speakers that can deliver as much—or more—deep bass, thanks to the use of more and/or larger drivers. All of which will make your buying decision considerably more difficult, but when push comes to shove, I would not be at all surprised if the excellent sound quality, impressive bass and good looks of Atlantic Technologies’ AT-1 get them across the line in your listening sessions… and most particularly if your friendly local dealer has sweetened the pot by shaving some dollars off the RRP! # greg borrowman

Who’s Behind Atlantic Technology?

Atlantic Technology is owned and operated by Peter Tribeman, who has an impressive track record in audio. After founding a company called Audio Pulse in 1975 (the company developed one of the first consumer-oriented time delay systems) he moved on to become president of NAD (USA) in 1980, in which position he famously arranged what is widely regarded as the first public demonstration of a Dolby multi-channel home theatre system at the 1982 Chicago CES. He left NAD in 1989 to found Atlantic Technology, though it was not officially incorporated as a company until 1992. Despite still owning and operating Atlantic Technology, Tribeman and six other principals formed a consortium to found another company, Outlaw Audio, in 1989, in order to manufacture electronics products for direct sale to consumers via the Internet. Two years after the company was founded, GoodSound’s Srajan Ebaen asked Tribeman why he thought Outlaw Audio’s business model would be successful. Tribeman told him: ‘Our seven Outlaw principals, myself included, are experts in failure. We all have worked in this industry for decades. We’ve designed, manufactured and sold every product in the book. We’ve learned what works and what doesn’t. We know about engineering and manufacturing. During our combined 120 years of experience, we’ve enjoyed some successes, but we’ve also committed many mistakes—hopefully we’ve learned a bit from those. We feel that we now have the right template to offer really successful products.’ In the almost two decades Tribeman has owned Atlantic Technology, he has certainly demonstrated a knack for hiring talented people to work for him. So far, Atlantic Technology has used the services of a number of famous loudspeaker designers, including Vance Dickason (author of the Loudspeaker Design Cookbook), Martin J. King (the world’s foremost authority on quarter-wave transmission lines) and Phil Clements (founder of Solus/Clements Loudspeakers). The company is headquartered at 343 Vanderbilt Avenue, Norwood, Massachusetts and has recently been granted trademark protection for the use of the letters ‘H-PAS’ in relation to loudspeaker sales, hence the ‘TM’ appearing after them whenever the letters H-PAS appear in Atlantic Technology’s literature. G.B.

Behind H-PAS Technology

While I have no doubt at all that the particular enclosure design that is used in Atlantic Technology’s AT-1 is very effective at delivering good bass, I do harbour doubts as to whether the cabinet design is either new or innovative. Indeed the internal layout of the cabinet looked to me to be practically identical to one shown in a long-expired patent granted to Philip R. Clements and Donald R Smith more than 30 years ago (US Patent #4373606). And although one US-based reviewer (Daniel Kumin) says the technology in the AT-1 was described to him by Atlantic Technology’s team as ‘combining elements of acoustic suspension, inverse horn and transmission line designs’ (SoundandVision October 2010), the AT-1’s cabinet would seem to me to be just a small-volume bass reflex cabinet containing two small bass/midrange drivers. Such a small volume enclosure would require a long vent to tune down near its claimed low-frequency limit, and such a vent is indeed provided inside the AT-1 enclosure, running down the inside of the rear wall. Using such a long vent has several well-documented disadvantages, which include that it magnifies driver distortions, can result in port noise and, perhaps most significantly, that it puts a ‘suck-out’ in the direct frequency response radiated forward by the bass driver(s). So what would be the ‘classic’ acoustical engineering solution to these problems, using existing knowledge? According to the expert acoustician I consulted, these effects could be eliminated, in his words: ‘…by another pipe, or stub, acoustically coupled to the vent e.g. by placing its opening close to the opening of the first one. This second organ pipe, stopped this time at one end, is a quarter wavelength stub tuned to the frequency of the first and is thus approximately (not exactly, due to end effects) half the length of the vent. This chamber need not, of course, be a λ/4 stopped pipe. It could be a Helmholz resonator, another small vented box, tuned to the vent’s λ/2 frequency.’

And, looking inside the cabinet of our review sample of the AT-1, this is exactly what I found—a separate vented chamber, with its opening close to that of the main vent that runs down the inside of the rear wall and exits on the front baffle at the base.G.B.

Readers interested in a full technical appraisal of the performance of the Atlantic Technology AT-1 Loudspeakers should download the laboratory report. Readers should note that the results mentioned in the report, tabulated in performance charts and/or displayed using graphs and/or photographs should be construed as applying only to the specific sample tested.

Atlantic Technology AT-1 Loudspeakers

Brand: Atlantic Technology
Model: AT-1
Category: Floorstanding Loudspeakers
RRP: $4,500
Warranty: Five Years
Distributor: Network Audio Visual Pty Ltd
Address: Unit 6B, 3–9 Kenneth Road