Turntables, Arms & Cartridges

Among the Digital Stream Corp's many innovations was the development of the optical mouse with Microsoft. Miniature LED technology is also employed in its range of 'optical' pick-up cartridges [HFN Nov '15, Jun '17, Dec '17, May '19, Feb '21 and 'Oct 21]. Here the movement of a stylus modulates an LED light source as it falls on a photocell, generating an audio output. And LEDs are once again utilised in DS Audio's latest 'measurement device' to calculate the eccentricity of an LP via its run-out groove.

One of two integrated LED emitter/receivers is visible in our picture [above] – red light flooding from one aperture being detected through its reflection into the other. Any cyclical 'wobble' in the lead-out groove is detected as a modulation in this reflected LED light which, in turn, is used to calculate the lateral movement – the eccentricity – of the groove and LP in micrometres (µm). A pair of these emitter/detectors is employed to improve overall accuracy although the effectiveness of the technique will also necessarily be influenced by the flatness of the LP. PM