What a gap: the Heil Air Motion Transformer first appeared some 30 years ago, pretty much faded from sight, and then - whoosh!!! Up pop a couple of new systems using the legendary tweeter, from two unrelated sources. With the Heil AMT, though, it was only a matter of time: the AMT needed worthy amplifiers and an appreciation of ribbons to succeed - neither of which existed in 1972. After the European offering from the Jecklin crowd, the Heil AMT Aulos reviewed in June by AG, here's one made in the UK...albeit by an American.

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And being American, I just had to get my hands on a pair of Orchid LWO Deep Resolution Loudspeakers for a very good reason: I lived with a pair of the original ESS Heil AMT 4s back in my college days - 1973-4 - when my flat-mate and I combined our systems to create a 4-channel set-up. At the time, it was one of the more radical transducers, but then the late 1960s and early 1970s were far more exciting times than the present when it came to choice of speaker technologies: the Ohm Walsh driver, early Magnepans, a slew of electrostatics, plasma drivers, the first stirrings of Bose, and much more. We ended up with Heils because the store I worked in was an ESS agency. (My mother still uses the non-Heil ESS Tempests which I left with her when I emigrated.) While the passage of 27 years means that my memory of the sound is less than dependable, we had no complaints. The system cooked.

As Alvin mentioned, the AMT works by 'squeezing' air; the driver is in effect a long ribbon folded accordion-like into a small frame. And, bugger me if the unit doesn't sound in retrospect like a precursor to the Apogees. Orchid uses the AMT with a Volt 8in woofer and a 5in Beyma driver acting as a phase link, with a bi-wired crossover bearing polycarbonate capacitors and air-core inductors. (See sidebar.) The drivers are fitted to a sloped baffle in a floorstanding enclosure measuring 33x12x14in (HWD), but don't let the compact dimensions fool you: Orchid is firmly of the mass-and-rigidity-are-good school, so each speaker weighs just under 100lb. The cabinet is fashioned from a 1 3/4in-thick bi-layer MDF sandwich, finished in real hardwood veneers. A bass-reflex design, ported at the rear, the LWO enclosure presents each driver with its own acoustically isolated sub-cabinet. Also supplied for the speaker is an integral slate base with four M6 spikes.

Matching the LWO to assorted amplifiers proved simple, provided the amp has a reasonable amount of power on tap, despite the specs. Although the LWO seems conventional, it works best with big powerhouses amps, especially valved. Orchid specifies the speaker as offering 89dB/watt sensitivity, with an 8 ohm nominal impedance and a 4.5 ohm minimum. Thus it is not an amp-breaker, but the least I would recommend to drive it is a 50W/ch-plus tube amp, such as the McIntosh MC275. I also used the Krell FPB300 and the Musical Fidelity Nu-Vista 300, with the Marantz CD12 and SME 10/Series V as sources. Wiring included Kimber Select and Harmonix.

Because of the LWO's compact dimensions, I had no problems in my 12x18ft room. The speakers were positioned by the designer to fire forward; toe-in messed up the sound stage by increasing the front-to-back depth at the cost of much of the stage width. Orchid states that the 10 degree sloping front baffle provides proper time alignment for listening positions from six to twelve feet from the loudspeakers; my hot seat was 8ft from the speaker line and it was hard to better the location.

It's difficult for me to fall back on 'breath of stale air'/blast from the past gags because I simply can't depend on my sonic memory going back as far as the pre-punk/pre-disco days. Moreover, I stayed utterly blitzed on grass throughout my college years - the only way to survive a graveyard like Orono, Maine* - so the sound systems around me served as little more than a backdrop to mind alteration. (I'm amazed my LPs from that era bear no scratches.) Thus, while I do remember being impressed with the first-generation AMT, I can't even begin to suggest what the ESS AMT 4 sounds like by today's standards; I haven't heard a pair since June 1974. What I can tell you about the current Heil AMT, though, is all good. And I suspect that the driver has changed very little in the intervening years.

If I knew then what I know now...the Heil in the LWO has the kind of upper frequency coherence and poise which precious few tweeters can offer. The inverted dome Focal unit beloved of Wilson and others, the Dynaudio ESOTAR - it enjoys their speed but with a dipole-like openness, transparency and freedom from beaming which will immediately find favour with Quad ESL devotees and those who normally loathe boxes. In fact, my overall impression is of a speaker system aimed precisely at the sort of Quad user who craves greater slam but doesn't have the will to turn traitor and embrace Martin-Logan hybrids.