Consumer Electronics

DISCS

Records are normally made for replaying at three different speeds: 78, 45 or 33⅓ rpm. The first or standard type of disc is pressed in a hard non-pliable material called shellac. Record wear with this material is relatively high even under good playing conditions. Wear with vinyl, the pliable material used for 45 and 33⅓ rpm, microgroove type of disc, is very slight under comparable conditions. The main trouble with vinyl records is the tendency to collect dust through electrostatic attraction. A special anti-static inner sleeve is shown Fig. 9.10.

 

 

Fig. 9.10 Special anti-static inner sleeve

 

Standard records are made with diameters ...