Sound-Lab A-1 electrostatic loudspeaker Page 4

With the A-1, not only the midrange but the bass and treble are covered by a single driver driven uniformly over its entire area. The resultant cohesiveness is most persuasive. The best way to appreciate this is to keep the music simple and focus on a solo voice or instrument.

Let's start with the lower octaves. Gary Karr's rendition of the Adagio d'Albinoni (King K33Y 236) on double bass, while technically imperfect in spots [Mr. Karr manages to play out of tune, is what DO is trying to say here.—Ed.] is blessed with an astonishingly sympathetic acoustic space. The grandeur of the recording is breathtaking, the timbre of his Amati pushing all the right emotional buttons in me. I've heard this piece reproduced on a variety of box speakers with mixed results. The bigger boxes manage to convey the double-bass's lower-register extension and upper-body heft, but invariably color the upper bass with "boxy" colorations. These spurious resonances may sound euphonic to some ears, but in my view they do little but blur the speed and detailing of the upper bass, coloring this region darker than life.

The little box speakers actually do a better job of fleshing out bass detail and conveying the proper sense of speed through the lower octaves. Alas, they fail to dig low enough or energize the upper bass sufficiently. Thus, the minimonitor report card: detailed but anemic.

You've got to hear the Gary Karr recording on the Sound-Labs. The transition from deep to upper bass and beyond was seamless, free of false resonances; when Gary dug down, the effect was all the more startling because of the sheer clarity and lack of transient smearing. I had not previously experienced bass detail and timbral accuracy of this caliber.

Tito Gobbi's scintillating performance as Figaro in Rossini's Barber of Seville (Angel S3559 C/L) provides a litmus test of the lower midrange. The reproduction of a baritone with this much power and finesse is often marred by conventional speakers in several ways. The cohesiveness of the voice may be degraded by the crossover from the woofer to midrange driver. Even in a two-way, timbral accuracy may be marred by in-band resonances of the driver and box. Finally—and this is not widely appreciated—as the voice soars into the upper registers, the speaker's polar response (actually that of the midrange driver, often 8" in diameter) narrows. The result is that the power radiated into the room diminishes with increasing frequency, and with it the palpability and realism of the projected image outlines. Gobbi's rendition of Figaro's big aria in Act I is a marvel to behold; on the A-1s, image solidity and timbral purity were sheer joys. With other speakers, Gobbi's image size might shrink with ascending pitch—an effect not experienced in the opera house. With the Sound-Labs, image size did not waver or wobble: there he was, chest and all, standing right before me.

To evaluate the core of the midrange and the transition to the upper mids and lower treble, I can think of nothing better than female voice. Anna Moffo (Selected Arias, RCA LSC-2504) will do very nicely. The "Shadow Song" ("Ombre legere") from Meyerbeer's Dinorah offers a rollercoaster ride from lower to upper registers. Without any crossover at 2 or 3kHz, there were no discontinuities in the reproduction. There was no dichotomy between the lower and upper registers. Ms. Moffo's peaches-and-cream vocal color was reproduced without even a hint of textural impurity.

The same seamless flow of harmonic textures also applied to the upper octaves. I'm often asked my opinion of this or that dome tweeter (footnote 3). Most have characteristic sonic signatures. Some fizzle, others sizzle, but each leaves me with an aftertaste: dark, etched, metallic, chocolate, or vanilla. In contrast, the A-1 exhibited no obvious treble character. At times the treble turned slightly soft or grainy, depending on the particular amp in the system at the time or the makeup of the front end.

The Sound-Labs faithfully reflected what came before them. The A-1 did not suffer a split personality: It was integrated from top to bottom. What it offered in terms of speed and resolution was not confined to a particular region. Its character did not change as the program material gravitated from one frequency extreme to the other. The treble, while not as refined as that of the Plasmatronics, at least blended convincingly with the midrange, being just as detailed and quick. In the extreme treble, the impression was of being seated to the rear of the concert hall, the treble being somewhat rolled-off and muted. But because the effect simulated the live experience, I wasn't bothered by the resultant balance.

High-powered orchestral music proved no problem for the A-1s. A large orchestra and chorus, as in Walton's Belshazzar's Feast (EMI SAN 324), were suspended within the soundstage solidly and with the requisite tonal authority through the lower mids. Loud passages with the chorus in full voice never sounded better. There was no hint of strain or congestion—as long as the power amp was able to dish it out.

However, a couple of response limitations were evident. These speakers went deep, but were certainly not flat to 20Hz. Usable bass response in my room was in the high 20s. More significant was the A-1's tendency to "overload" in the deep bass at only fairly loud volume levels. At sea level, where the speakers could be driven at a higher bias level and thus operated more efficiently, the overload may not be evident except at very high volume levels. I use the word "overload" loosely here; technically, the diaphragm slaps against the stators and makes a nasty noise. Because of the staggered bass resonance, only some of the facets appeared to crack up at certain bass frequencies. There's no physical damage when this happens, but it certainly ranked high on my list of annoyance factors.

Beranek's Law
An ultra–high-end product inspires tweaking, and the A-1 is no exception. By now, Roger West has heard it all from excited customers. West has even invoked a "law of nature" to explain the phenomenon. "Beranek's Law" (after acoustician Leo Beranek) states that, whatever the modification, the modified product always sounds better to the modifier. Roger's reaction is tongue-in-cheek because of the variety of mods proposed to him and the fact that some make little or no sense. An example of the latter variety is bypassing the power-supply fuse or increasing it in value from ¼ amp to, say, 10 amps—which I actually did, on Michael Percy's strong recommendation. While I'm just as mystified as Roger as to why this should make any audible difference at all, I did observe a slight improvement in bass definition with the changeover to the larger fuse. The nice thing about this mod is that it's cheap and easy to reverse.

Some modifications do make sense; for example, mass-loading or stiffening the array frame. The latter approach was implemented by Albert Porter of Texas; he used nylon line anchored to the wall together with lead weights to tension the frame. That's too esoteric even for me. Another possibility is replacing the casters with something like Tiptoes. The idea here is to couple at least some of the array frame's energy to the floor. With a wood floor, such a strategy makes a lot of sense. Even in my room, with its carpeted concrete slab, anchoring the A-1s is still important.

The Sound-Lab A-1 is about elevating reproduced music to the level of the live experience. At slightly over ten kilobucks per pair, it's fairly priced for a high-tech product that really delivers this experience. That they succeed to this extent is a miracle that every audiophile should experience at least once in his or her lifetime. My wife Lesley will tell you that, when it comes to audio, I'm damned hard to please. The Sound-Labs do it for me; they've got me excited about music like never before.

My quest has been to find a loudspeaker that could satisfy me till the end of time. That quest was fulfilled with the arrival of the Sound-Lab A-1s. I stood before them with the same sense of awe evinced by Salieri (in Peter Shaffer's Amadeus) while examining Mozart's original scores: "They showed no corrections of any kind. It was puzzling—then suddenly alarming. What was evident was that Mozart was simply transcribing music completely finished in his head. And finished as most music is never finished. Displace one note and there would be diminishment. Displace one phrase and the structure would fall."

The A-1 is the true voice of music. It combines the traditional virtues of ESLs—the finesse areas of musical reproduction—with the power and dynamics typically associated with full-range dynamic speakers. Imagine the speed and transient control of an electrostatic infused with a convincing dynamic range and tonal authority. Sounds like a glimpse of heaven, doesn't it?

Footnote 3: Before responding, I usually smile and remind the listener that, many moons ago, I owned a pair of Plasmatronics speakers. I got pretty good at hefting full-sized helium gas bottles around the family room. The payoff came in dimming the room light and firing up those plasma drivers. The blue glow of the plasma jets would send me into ecstasy. There never was and never will be a better tweeter in this galaxy. Above 1kHz, the Plasmatronics were magical in their reproduction of transient detail. Anyone privileged to hear violin overtones handled by these speakers would forever have sonic fantasies about the wonder of that moment. What finally soured me on the Plasmatronics was the sad truth that the range below 1kHz—the range handled by the Audax drivers—was rendered in a totally ordinary and undistinguished fashion. There's an awful lot of music below 1kHz, and the dichotomy in performance between the out-of-this-world plasma tweeter and the box below eventually drove me up the wall.—Dick Olsher
Sound-Lab Corporation
153 N 400 W Street
Gunnison, UT 84634
(453) 528-7218

remlab's picture

...issue I ever bought. I never forgot about the Mylar thickness issue. I remember saying to myself, "what if John hadn't tested the speaker?" There would have been a whole bunch of screwed up A-1's out there, probably to this day. That's what made me realize how important the testing of all equipment is. How often has equipment malfunctioned or been out of spec  during Absolute Sound reviews without them even knowing. Obviously, having measured A-1's previously did help in this case.