Turntables, Arms & Cartridges

Inside the Master 1 light from an LED shines on a very sensitive photocell. This generates an electrical current that’s modulated by a vibrating sapphire cantilever interrupting the light path. It’s a derivative of the technology used in optical pick-ups for guitars and in optical mice and is powered by an external supply [see picture] which also serves to equalise the pick-up’s return feed. The picture shows the solid copper plates connecting no fewer than six 120,000μF reservoir capacitors per channel inside this OTT power supply!

Traditional MM/MC pick-ups are velocity-sensitive devices whose voltage output not only increases with groove excursion but also with frequency (as the stylus moves more quickly). By contrast, DS Audio’s photo-electric conversion is solely sensitive to the amplitude of the movement of the stylus. However, as LPs are cut with the RIAA replay characteristic then both MM/MC and optical pick-up types still require equalisation before the audio signal is passed to a standard line-level pre or integrated amplifier. PM