Innovative Hi-Fi: 47 Laboratory's Koma Turntable

January 23, 2010

January 23, 2010

Innovative Hi-Fi: 47 Laboratory’s Koma Turntable
Source: Hi-Fi Choice

There’s a number of ways to ensure that the platter of a turntable rotates smoothly – carefully regulated motor (either belt or direct drive), heavy platter with a large moment of inertia, additional flywheels, etc. One of the more unusual methods is employed by the iconoclastic 47 Laboratory of Japan, whose 4724 Koma has twin contra-rotating platters.

Sansui tried their hand at implementing the concept of contra-rotation in their XR-Q7 and XP-99 quartz-lock direct drives back in the early 1980s, both of which featured the Silent Synchrotor system to prevent variations in the rotational force generated by the direct drive motor from creating vibration in the plinth. Sansui’s SS consisted of a second rotor beneath the one driving the platter, the former spinning in the opposite direction to the latter, thereby canceling any torque fluctuations (at least in theory).

The Koma is a more fully realised turntable: its two solid aluminium platters, driven synchronously by the same orange belt, float on neodymium magnets to reduce friction and bearing noise. According to Junji Kimura, the Koma’s designer: ‘As for the effect of the counter-rotating platter, imagine a single platter turntable placed on a boat floating on calm water. No matter how we smooth out the friction of the rotation, we can not completely eliminate it, and given enough time, the force created by the rotation would be transmitted to the turntable base, to the boat, then to the water, making the boat rotate with the rotation of the platter and cause ripples on the water surface. The counter rotating platter is to neutralize this force created by the primary platter.’

The Tsurube Tonearm

The suspension is divided into two points, the horizontal suspension at the arm pivot and the vertical suspension at the middle of the arm length, to improve the trackability and to reduce the effect of the arm mass. By adjusting the support at the tip of the headshell, it eliminates the low infla noise caused by the warp of LP surface.