Kuzma Stabi XL Turntable/ Air Line Arm, Walker Proscenium Black Diamond Record Player

Kuzma vs. Walker: The Title Bout in Analog Playback

As most of you alread y know , when analog records are mastered , the cutter head that inscribes the signal in the lacquer blank travels in a straight line from the outer edge toward the center of the spinning disc. It is generally accepted that, all other things being equal, the tonearm should follow the same line as the cutter head for the most accurate playback and lowest tangential error. Of course, all other things aren’t equal, but we will come to that in a moment.

Both the $40k Walker Proscenium Black Diamond and the $28.5k Kuzma Stabi XL turntable with Air Line tonearm are air-bearing, tangential (straightline- tracking) record players. Both tonearms ride on a very thin (10-micron) cushion of air, which acts as a frictionless bearing; both arms trace the same straight line across the LP that the cutter head did, theoretically playing back discs with zero tracking error. Why, then, do they sound so different?

Well, part of the difference is attributable to the different ways these two superb record players spin LPs.

The Kuzma Stabi XL is a suspensionless, modular, twin-belt-andmotor- driven turntable that depends on the carefully chosen materials it is made of for damping. Since it has no suspension and no means to adjust level, the Kuzma ’table and arm must sit on a sturdy stand or air-suspension table, like a Vibraplane, that can itself be precisely leveled.

The Stabi XL doesn’t have a traditional rectangular plinth. Instead, it has a 59-pound “base”—a beautifully machined cylindrical hunk of brass, with an inverted, oil-bathed, non-metallic, ruby-tipped bearing-shaft in its center. An aluminum subplatter is fitted snugly onto the bearingshaft, a 48-pound platter—made of a sandwich of aluminum and acrylic plates and topped with a proprietary rubber-and-textile mat—onto the subplatter. Drive is supplied to the platter by two cylindrical, brass-encased motors that fit into cutouts on either side of the turntable base. Twin belts run from both motors around the subplatter—a symmetrical setup that is said to maximize stability and minimize vibration. Motor speed is controlled by a quartz clock in the Stabi XL’s outboard power supply. The whole thing looks exceptionally cool—a genuine work of applied art.

The Walker Proscenium Black Diamond is an air-suspended, singlebelt- and-motor-driven, air-bearing turntable. It, too, depends on the mass and composition of its component parts to provide damping, although the Walker also sits on air-suspension feet that decouple it from whatever else it rests on. Unlike the Kuzma, the Walker can be leveled via adjustments to the pressure in its feet, and since it has its own built-in air-suspension system, you will not need to buy a Vibraplane—something to keep in mind when you consider the considerable difference in price between it and the Stabi XL.

The Walker does have a rectangular plinth—a 165-pound composite of crushed marble, epoxy resin, and lead, finished in a piano-black gel-coat. Unlike the Kuzma, the Walker does not use a conventional ball-andthrust- plate bearing. Instead, its platter, like its tonearm, rides on air. A ten-inch-diameter air-bearing subplatter (the largest yet made for a turntable) and its attendant plumbing are fitted into a large hole in the center of the plinth. A 75-pound, fully-sealed lead-platter is then placed (very carefully) onto this airbearing subplatter. Pressurized air routed from reservoirs in the Walker’s huge, filtered (for moisture, dust, and oil) air-supply box is sent through three low-pressure, hand-lapped jets in the air-bearing subplatter, lifting the massive lead platter and allowing it to rotate frictionlessly. Because of the size of the airbearing, it only takes 1.2psi to lift the platter.

Drive to the Walker ’table is supplied by a single, outboard, low-torque, instrumentgrade, ball-bearing AC motor, encased in a marble-epoxy-lead box of its own and mounted on Walker Valid Points (giant brass tiptoes). The motor sits in a brass cradle that allows you to tension the silk belt that runs from the pulley to the platter and is controlled by Walker’s Ultimate Motor Controller—an outboard device that filters AC in addition to stabilizing speed.

The turntables—with their diverse suspensions, bearings, drives, materials, and masses—are sufficiently different to account for some of the dissimilarities in the way the Kuzma and Walker sound. But, then, their tangential airbearing arms are also different.

The Kuzma Air Line is what might be called a “traveling air bearing,” in that its sleeve-like bearing glides (with the tonearm, which is attached to it) on a cushion of air along a fixed, polished, large-diameter spindle. The Walker is what might be called a “fixed air bearing,” in that the bearing does not move along a large-diameter spindle; rather, a smalldiameter spindle (to which the tonearm is attached) moves, on a minute cushion of air, through a long, pressurized hole in the bearing itself.