The MMC principle was adapted to track 4-channel records: both Quadradiscs and SQ. MMC 6000 would track both mono and stereo records with the utmost fidelity. It was designed for record-players with tangential arms. The stylus was the Pramanik diamond, named after its inventor: engineer S K Pramanik from Bang & Olufsen’s Laboratories.
The diamond’s radii were 7 um/2 x 50 um. It was a refinement of the elliptical shape, rather like the shape of the cutter-head, and enabled greater contact with the undulations of the record groove. The cantilever was made of berylium – a material which is harder yet lighter than popularly-used aluminium. Effective tip mass was 0.22 mg. Compliance was higher than 30×10-6 cm/dyne. Recommended- stylus pressure was 1g. The total frequency range was 20-45.000 Hz.
In the audible range: 20-15.000 Hz there is less than 1.5 dB variation and in the inaudible range 20,000-45,000 Hz where the carrier frequencies lie, the pick-up fulfils RCA/JVC’s specifications for a Class A discrete 4-channel pick-up cartridge. Each cartridge is an integrated, individually calibrated unit. The stylus unit is not separately replaceable since it is part of the integrated unit. An individual frequency response curve traced on a Bruel & Kjaer level recorder and a complete Calibration Card were enclosed with every MMC 6000 sold.