Unity Audio Signature 1 loudspeaker
Unity Audio is a relative newcomer on the loudspeaker scene, first listed in the 1989 Audio Directory. Without any extraordinary promotional effort, they've built up a respectable dealership network and have acquired an up-and-coming reputation, including a following among members of the Westchester Audiophile Society, the gang whose escapades are occasionally chronicled in Sam Tellig's column. The Signature 1 is the third most expensive speaker in Unity Audio's line, after the $15,000/pair Professional Applications Reference Monitor (PARM) and the $5500/pair Fountainhead Signature (discussed by Sam last April in Vol.15 No.4). I've heard several of the Unity Audio models at various shows, including the Signature 1 at the Toronto CE-EX in 1990, and have been impressed by the high quality of sound they seemed to offer. I welcomed the chance to put the Signature 1 through its paces in my listening room.
Description & design
Gorgeous. That's probably the best word to describe the speaker's appearance. (WordPerfect suggests "dazzling," "ravishing," "resplendent," "splendid," and "stunning" as synonyms, but I'll stick with my original choice.) These slim towers are finished in hand-picked wood veneers (the review samples were rosewood with birdseye maple trim), and would not look out of place in a store that sells "fine furniture." Of course, a speaker's appearance is of no concern to a real audiophile, but for others the Signature 1's high DAF (Decorator Acceptance Factor) will be an asset.
The Signature 1 box is sturdy as well as attractive: those beautiful wood veneers cover a ¾" Medite cabinet braced every 6". The driver complement includes a front-mounted 1" Morel silk-dome tweeter, 7" Vifa cast-frame midrange, and a downward-firing SEAS 10" cast-frame woofer. Four sharp spikes are provided for mechanical grounding. The speaker can be supplied set up for bi-wiring, with solid copper Cardas binding posts; the internal wiring is Purist Audio Design silver. The grillecloth covering the tweeter and midrange is removable, and, like most manufacturers of audiophile-quality speakers, Unity Audio recommends you do exactly that for maximum performance.
Although the Signature 1 drivers are conventional, the crossover is not. According to Unity Audio's Bob Grost, crossover design is much more complex than commonly believed; the Unity crossover (patents pending) addresses what he sees as fundamental problems in conventional crossovers. First, the Signature 1 crossover is said to produce phase coherence by electrically compensating for the spatial distribution of the frequency response of the midrange and the tweeter (ie, the location on the cone and dome where specific frequencies are generated). Thenand this terminology might raise some eyebrowsthe crossover is described as "balanced" and "class-A."
Bob Grost's use of these terms is, like the crossover itself, rather unconventional, in that he doesn't mean "balanced" in the same sense that the term is used to describe amplifiers and cables (the speaker doesn't have positive, negative, and neutral terminals), and of course the speaker has no output devices to be run in class-A, -B, -A/B, or any other mode of operation. What he means by balanced is that the crossover is split between the positive and negative terminals of the speaker rather than being just on the positive side. The crossover also has a "current wing" that keeps capacitors charged, a trick that is said to reduce switching distortion, just as with class-A amplifier circuits.
Now all this may represent solutions to hitherto-overlooked problems in crossover design, or it may just be technobabble. What really counts is the sonic result, but to find out about that you'll have to wait until the section on "Sound." No peeking!
The Signature 1s were delivered (they're just under the UPS weight limit) while I was still doing listening tests on the Alón IVs, so, mindful of speakers' need for a break-in period, I put the Signature 1s to work in my video system, driving them with an oldie-but-goodie Audionics CC-2 amp. Two weeks later, I got a call from Bob Grost, saying that he and Unity Audio's marketing manager, Kathy Grost (yes, they're married), would like to come help me set up the speakers. When they arrived, I already had the speakers in the listening room, more or less in the same position where I'd had the Alón IVs. This setup seemed generally okay, but Bob Grost was not quite satisfied.
For three or four hours, we listened, moved the speakers, listened again, moved the speakers again, played with RoomTunes placement, etc., until he was able to give the setup his blessing. This turned out to yield close to my favorite 60° listening angle, but with the two speakers in a slightly asymmetrical arrangement; ie, at different distances from the side and back walls. He also adjusted the position of the spacer between the speaker and the floor spike, increasing the distance between the floor and the bottom of the speaker. The speakers were toed-in slightly; RoomTunes were placed in the corners behind the speakers, and one along each sidewall about 18" forward of the speakers. My usual listening position is with my ears at a 38" height, which is nearly level with the top of the Signature 1's midrange driver.
If I had to choose a single word to characterize the Signature 1and "musical" was already takenit would be "quick." Plucked instruments such as guitars (check out the Bruce Dunlap track on the first Stereophile Test CD, and the Gavin Lurssen track on the second one), harp (eg, Susann McDonald, Klavier KCD-11004), and percussive sounds (eg, All Star Percussion Ensemble, MMG MCD-10007) had a clarity and lack of transient overhang that reminded me of my original Quad ESLs, speakers that are nearly unequaled in this area. They resembled the original Quads in another aspect: transparency. Throughout the broad midrange and the highs, there was a strong sense of "seeing through" to the program material, with little in the way of obscuring coloration or "grundge" from the speaker. The quickness and transparency allowed the fine detail of the ebb and flow of the musical performancewhat some refer to as "microdynamics"to be communicated very convincingly.