Platter with magnetic bearing
Platter is sandwich type made of two 15 mm. aluminium discs with 10 mm. acrylic insert. Thickness 40 mm.,diameter 320 mm., weight 7 kg. Has a conical hole for bearing spindle. On bottom side can be made ring with gaps ( in photos you see platter with 240 gaps ring ) for optic sensor of speed controller or rotation counter. Mat - natural leather.
Radial swinging ≤ 0,05 mm, vertical swinging of platter edge ≤ 0,2 mm.
As platter is not solid, has layers of acoustic different material, it has no resonances.
Bearing is classical type - a 9mm. steel shaft within a steel sleeve. The outer surface of the shaft and inner surface of the sleeve are precisely polished. Tip of shaft rests not on steel or ceramic ball, as usual, but on magnetic pillow, created by two neodymium magnets. This eliminates hard mechanical thrust between the shaft and bottom of bearing and reduces vibrations of platter. As diameter of magnets is only one inch and distance to tonearm is long, this does not affect the cartridge. The assembly is located in a 40mm diameter aluminium housing that is filled with oil. Length of bearing – 90 mm. Flange diameter – 100 mm.