Zero-Point Tangential Tonearm

The Zero-Point Tangential Tracking Arm does not pivot. It has no pivot point, no bearing axis, and no angular displacement during playback. The arm moves in a straight line, perpendicular to the groove, across the entire surface of the record. Tracking error — the angular difference between the cantilever axis and the tangent to the groove — is 0.000 degrees at the lead-in, 0.000 degrees at the midpoint, and 0.000 degrees at the run-out. This is not an approximation. It is a geometric fact. A tangential arm cannot produce tracking error any more than a straight line can be curved. We do not claim superiority over pivoted arms in this regard. We simply observe that the problem they attempt to solve does not exist in our design.

The arm carriage rides on a full air bearing over a 400-millimetre rail machined from a single boule of monocrystalline sapphire. Sapphire was selected for three reasons: it is the second-hardest natural material, it is thermally stable to within 0.02 ppm/°C, and it has absolutely no magnetic susceptibility. The air gap is maintained at 4 microns by an external vibration-isolated compressor operating at 22 dB SPL — quiet enough that it has been mistaken for a piece of equipment that is turned off. The bearing surface will not wear appreciably within the expected lifespan of the owner, the owner's children, or the geological epoch in which we currently reside.

Lateral position is maintained by an optical edge-tracking servo that monitors the groove wall at 1 kHz with a spatial resolution of 0.001 millimetres. When the stylus deviates from tangential by any measurable amount, the servo advances the carriage to correct. In practice, the correction signal is so small and so continuous that the arm appears motionless to the naked eye. It is, in fact, making approximately nine hundred micro-corrections per second. The arm tube and headshell are fabricated from vacuum-deposited beryllium — the lightest structurally rigid metal — yielding an effective mass of just 6.2 grams, which permits tracking forces as low as 0.1 grams for the most compliant cartridges available.

The anti-skate specification reads "not applicable," and we wish to be precise about why. Skating force is a geometric consequence of the offset angle required by pivoted tonearms: the stylus drag vector does not pass through the pivot, creating a torque. The Zero-Point has no pivot and no offset angle. There is no torque. Skating force does not exist here — not because we have compensated for it, not because we have reduced it below audibility, but because the geometry that creates it is absent. We did not eliminate skating force. We eliminated the conditions under which it occurs. This is, we believe, the only honest approach to the problem.