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

Kuzma vs. Walker: The Title Bout in Analog Playback

Perforce, the Kuzma Air Line’s traveling bearing is considerably shorter than Walker’s fixed bearing—just two inches across. Lined on the inside with a highly porous material and supplied with air from an outboard pump at extremely high pressures (65psi), the bearing, says its designer Franc Kuzma, is so stiff that it’s virtually immune to mistracking caused by the centripetal forces that “pull” the cartridge through the grooves of an LP and that tend, simultaneously, to twist it away from its ideal straight-line course.

Walker’s fixed air-bearing is housed in a large rectangular brass block—six inches long, two inches wide, and two inches tall—with a hole, just a bit larger in diameter than the spindle that travels through it, running through its center. Air from the same huge outboard box that supplies the air-bearing turntable and airsuspension feet is piped into the hole in the tonearm-bearing assembly at 50psi through eight hand-lapped jets in what Walker calls a “high pressure, medium-flow” arrangement. Once again, because of the bearing’s stiffness and the considerably greater length of spindle that is being “supported” by the air in the bearing, the effects of torsion are virtually eliminated.

Bearing size and type are not the only differences between the two tonearms. For one thing, there is the way they are attached—or not—to the turntables. As with the free-standing modular parts of the Kuzma Stabi XL ’table, the Air Line tonearm is itself free-standing, bolted at its far end to a thirty-one-pound brass pillar that can be moved up and down via a thumbscrew. Kuzma supplies a digital VTA gauge that reads the height of the pillar with great precision, allowing you to experiment with VTA and return precisely to the same spot on the gauge. You can also adjust VTA, precisely and repeatably, via a numbered knob on the tonearm assembly itself.

Because it is not physically attached to the ’table, the Air Line tonearm does not “see” any of the noises or resonances of the turntable/motor assembly, save as they are fed back through the stand on which both ’table and arm sit. Not being fixed to the table does, however, make arm setup a bit more complicated, as the entire freestanding arm/pillar must be carefully moved, rotated, and leveled vis-à-vis the platter to make sure that the tonearm travels at the right height in a straight line across an LP. (Kuzma supplies well-written instructions and an alignment tool that make this process a snap.)

The Walker tonearm is attached to the ’table—sort of. The massive air-bearing block is fixed on top of two sizeable carbon-fiber rods that come up through holes in the plinth. Although the rods are bolted on their bottom to the plinth’s base, you have to wonder how much vibration the tonearm might see, given its own material composition, the mass of the air bearing and plinth, and the facts that both tonearm/spindle and platter ride on air and that the motor is physically isolated from the ’table. Although not as cool or convenient as the Kuzma in this regard, the Walker arm also allows precise repeatability of VTA adjustments via two knurled knobs on the tonearm pillar, and because the Walker’s bearing assembly and arm are fixed in relation to the platter, arm/cartridge alignment is somewhat easier.

Another significant difference between the Kuzma and Walker is the material composition of their tonearms. The Kuzma uses a stiff, hollow, conical tube—beautifully machined from three solid blocks of aluminum and damped internally—that is welded to the traveling air bearing. Air is fed to a nipple on the bearing via flexible tubing that runs between it and a valve at the supported end of the tonearm assembly. (A nifty little gauge at the free end of the tonearm assembly tells you how much air pressure you’re running through the bearing.) Air is supplied to the bearing by a regulated, oil-lubricated, industrial-grade compressor that filters for dust and moisture. Because of the occasional loud “spitting” noises it makes during its duty cycle, the compressor is best stored in a separate room, with the air piped to the bearing via thin (4mm) PVC pipe.

The Walker Proscenium Black Diamond turntable is fitted with an entirely different arm/spindle assembly than the Walker Proscenium Gold (thus the new moniker). Gone are the small-diameter carbon-fiber arm-tube and carbon-fiber spindle of the Gold; in their place are a small-diameter armtube and spindle made of an entirely new, expensive, proprietary material—some sort of ceramic-composite that is said, by Walker, to be twenty-times stiffer than the carbonfiber arm/spindle and so hard it can only be cut with diamond bits. Whatever this mystery material is, the new arm and spindle have made a huge improvement in the sound of the Walker ’table (and the Proscenium Gold was scarcely low-fi to begin with).