AOM Logo June 1998


Music in the Round
The Wilson Benesch Circle Turntable and ACT 0.5 Tonearm


Blair Roger

Made to Measure
Two feelings constitute my litmus test of quality when confronted with a new design. The first is almost a conscious thought: "Why didn't I think of that? It's so obviously right." The second feeling is more like a resonance that comes when I stumble across a work of formal perfection and functional elegance, like the Porsche 356A, any of Schubert's lieder or a ring of gold. It is a feeling that we live in a benevolent universe. These were exactly my responses to the Circle turntable the first time I saw one.

Wilson Benesch is a relatively new force on the analogue scene in North America, although they are highly revered at home in the U.K. They are a firm founded on engineering knowledge of high-tech materials, precise analysis of the problem at hand, and innovative solutions. Their web-site's first sentence about the Circle spoke volumes: "The primary function for any turntable is to provide a platform for measurement of a moving object, the vinyl…". They go on to state that the design philosophy behind the Circle is set-and-forget, combining the precision of high-performance materials with classically simple aesthetics. I have to say that visually, Wilson Benesch has succeeded in creating an outstanding piece of industrial design art. After some contemplation, I would call the Circle a Rega Planar 3 as Frank Lloyd Wright might have revised it. With the platter removed, the whimsical interplay between the masses on the surface of the upper plinth is very pleasing. The constant and consistent reliance on the motif of the circle is amusing and clever. That it should serve the purposes of engineering is even more remarkable. The fine satin finish on the black composite plinth and machined aluminum cylinders gives the immediate impression of a unique piece of sculpture having crossed paths with a precision laboratory instrument. I believe that this is exactly what Wilson Benesch has intended.

Wilson Benesch Circle

A Plinth to Stand On
The Circle is an unsuspended, split-plinth design whose simplicity I find commendable. The main objective here is stability, as well as damping and isolation of the tonearm from sources of vibration. The plinth is made from two one-inch thick composite disks, twelve inches in diameter stacked one above the other. The lower disk serves as a vibration sink for the motor housing, which pokes up through a circular cutout in the upper disk. A fractional space and low compliance suspension points separate the two halves of the plinth.

The overall impression I have of the Circle in action is stability; particularly of pitch and tracking. The high performance Papst motor and power supply are silent in operation, transmitting no vibrations to finger tips lightly placed on the upper surface. It is a powerful motor too, bringing the acrylic platter up to speed with no lag. I never heard any pitch variations in three weeks of intensive auditioning. A short, round-section rubber drive belt is the only physical connection between the motor pulley and the sub-platter. Changing the belt position on the pulley provides for both 33 1/3 and 45 RPM operation.

The phosphor Bronze plain bearing, though quite humble in comparison to that of the Immedia RPM for example, proved totally satisfactory in this application. The spindle and bearing-well are machined to a very fine finish and very close tolerance fit. The spindle is lubricated with only a few drops of light oil and spins on a tool steel ball at the bottom of the bearing-well. Whatever noise the bearing might produce is effectively drained away into the massive machined aluminum disk in which it is mounted. A new level of background 'blackness' was achieved on every record I played. As a devoted Well Tempered Table and Arm user, it is rather painful for me to admit that my old standby has been bettered in this respect. I can console myself however, by looking at the Circle's arsenal of high-tech stealth gear needed to surpass one of the best.

The ACT 0.5 tonearm is really the most interesting part of this package. Wilson Benesch claims that their mastery of carbon fiber composites gives them a virtual carte blanche in developing their tonearms. They are unconstrained by previous engineering ideas and the shortcomings of conventional materials. The armtube is formed from an interwoven matrix of carbon fibers, said to have superior damping characteristics when compared with other, non-woven carbon fiber tubes. Interestingly, the armtube bears a resemblance to the SME V, or for those looking upwards, the RB300 with its one-piece design. The arm pillar is mounted in the centre of an aluminum puck with an Allen-head set screw deeply recessed in the side. A very significant part of the design is the way in which the armboard has been isolated from the plinth. Two parallel shafts of carbon fiber protrude from the central housing forming a cantilevered support for the substantial mass of the armboard. One look tells you that there won't be much interplay between stylus vibrations and those originating in the plinth. I have no doubt that this method of isolation combined with the designer composite armtube has a significant effect on the clarity with which the Circle speaks.

Wilson Benesch Circle - Top View

A Tough ACT to Follow
The arm bearing deserves special consideration. Wilson Benesch has called this variation on a uni-pivot design a kinematic bearing as it has evolved from the engineering principle of kinematic location. Briefly, this theory states that there are only six types of motion experienced by a rigid body: movement in the three axes of our three-dimensional world, and rotation in each of these axes. These motions are known as the six degrees of freedom. Controlling the motion of a body in space requires one to limit its movement in each of these six degrees. The kinematic bearing allows just two degrees of freedom. The cartridge is only allowed to move vertically and horizontally across the record. All linear motions, it is claimed, are eliminated so that the cartridge has a super stable platform from which to carry out its task as a measuring instrument. In physical detail, the pivot point of the arm is a pyramid of four tiny carbon chrome balls constrained beneath a conical collar.

Complaints Department
I had some difficulty bolting my Lyra Lydian cartridge to the non-removable headshell. The straight edges of the cartridge were hidden beneath the gently rounded curves of the mounting plate, making initial adjustments nearly impossible. Fortunately, Wilson Benesch provides a cardboard template disk with an ideal tracking curve printed on it. I soon had the squared-off nose of the Lydian in sight and could proceed with the setup tasks. Setting the tracking weight was almost a pleasure. It was simple to slide the low-slung counterbalance to-and-fro on the superbly machined shaft. The tolerance on this piece was delightful in terms of feel and friction fit: no set screws required.

As I started to balance the arm and cartridge, a remarkable thing happened: I could feel the arm bearing come alive in my hands as I approached the specified tracking weight. This is the only way I can describe it! The kinematic bearing is that sensitive.

Another surprise was how easily and accurately I could set the azimuth for the Lydian. A slight rotation of the counterbalance on its shaft caused the longitudinal axis of the tonearm to shift in the opposite direction. I was able to set the azimuth by ear, very quickly locking-in a wide, stable soundstage.

Setting the proper VTA was a different matter. There simply wasn't enough adjustment range available. I could get very close to the best setting, but with the arm pillar dropped right onto the armboard the VTA was still a couple of degrees higher than I would have liked. This, however, did not have a significant effect on my overall impression of the sound of the Circle.

The OEM cueing control is only good at best and is really only suitable for lifting the stylus out of the groove. The rounded underside of the armtube rolls around on the cueing bar in such a way that precise groove selection is almost impossible.

Associated Components

Analogue: Wilson Benesch Circle Turntable/ACT 0.5 Tonearm, Well Tempered Turntable (with Black Damped Platter) and Tonearm (with LP Labs' carbon fibre armtube), Lyra Lydian phono cartridge
Preamplifier: Audio Research SP9 Mk.II, Siemens gold-pin tubes.
Power Amplifier: YBA 3 alpha
Loudspeakers: Quad ESL-63 USA Monitors

The Sound
The first thing that hits you about the Circle is its pinpoint imaging: side to side, front to back and in height as well. Take, for example, the numerous percussion flourishes in the score of Debussy's Iberia [Classics LSC-2222]. The castanets and tambourines are suddenly located freely in space, quite high above the loudspeakers. Solo instruments are portrayed with rock-solid positioning and plenty of air.

The noise floor, even with a low output cartridge like the Lydian, is exceptionally deep and black. The 1980 RCA Red Seal pressing of Takemitsu's Waves [ARL1-3483] is hardly state-of-the-art, and yet the expanse of RCA Studio A spread before me, populated with living, breathing musicians.

It was easy to play records, one after another because of the superb resonance control designed into the Circle. Vinyl clicks and pops faded softly into the inky background and exceptionally noisy vinyl was rendered much more palatable. Even the flinty edge of Robert Lucas's voice on Usin' Man Blues [Audioquest AQ-LP1001] was controlled without losing any soulful impact. His Dobro slide guitar hung in the sonic space between my Quads so convincingly that I could almost see his fingers moving.

The Water Lily Acoustics recording, Saudades [WLA-CS-16] was a revelation of what purist Blumlein microphone technique can achieve in terms of depth of soundstage and lateral imaging. These improvisations on South American rhythms exhibited a purity of timbre and realism when played on the Circle that was thoroughly engaging. Listening to this record left no doubt as to how accurately I had set the azimuth and overhang on the Lydian - the Circle is a superb groove-measuring machine. In the grips of the ACT 0.5, the Lyra Lydian tracked the most complex high treble percussion passages with a new sense of composure that bordered on indolence. Without a doubt, the tonearm's one-piece armtube contributes greatly to a feeling of wholeness and continuity in any instrumental or human voice. No part of the midrange or treble is highlighted by spurious resonances, and this allows the listener to relax deeply into the music.

Alas, large-scale orchestral recordings proved to be the downfall of the Circle. The redoubtable Symphony No. 1 by Shostakovich [RCA/Classic Records LSC-2322] simply lacked the heft and drive in the midbass that I had become accustomed to. In similar fashion, the Circle's portrayal of Holst's The Planets [Previn - EMI ASD3002] exhibited a general lack of dynamic impact which soon led to a feeling of disengagement and catcalls from the assembled cognoscenti.

Conclusion
What a pity. So close to sonic nirvana (even glimpsing it momentarily!) and yet so far. Yes, this may very well be the perfect machine, but something is missing: a bit of soul perhaps? The answer is less metaphysical than that. The acrylic platter and felt mat are at fault, plain and simple. If Wilson Benesch are the wizards of high-tech composites that they evidently are, why didn't they put a platter with more chutzpah on the Circle? I'm going to be a bit cynical and say that they had to do something to distance this unit from its big brothers.

If you listen primarily to vocals, soloists and small ensembles, you may find, as I did, that the Wilson Benesch Circle/ACT 0.5 is a superb analogue playback system - just hold the Shostakovich.


Circle Turntable/ACT 0.5 Tonearm
Manufactured by Wilson Benesch Ltd.
Falcon House, Limestone Cottage Lane, Sheffield England, S6 1NJ
phone: + 44 (0) 1142 852656, fax: + 44 (0) 1142 852657
web: http://www.wilson-benesch.com, e-mail: info@wilson-benesch.com
Price: US$2995
Source of review sample: Extended Dealer Loan
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