among their advantages over the competition, they were played with a permanent conical diamond stylus, while lateral-cut records were played with a ten-for-a-penny steel needle that quickly wore to fit the groove contour and was meant to be replaced after one use. a feed screw mechanism inside the phonograph moved the reproducer across the record at the required rate, relieving the groove of that work and thus reducing record wear. this design was in response to the patent held by the victor talking machine company that states that the groove of the record itself is what propelled the reproducer across the surface of the record via the needle. the playing speed for diamond discs was specified at exactly 80 revolutions per minute, at a time when other makers' recording speeds had not been standardized and could be as slow as 70 rpm or even faster than 80 rpm, but were typically somewhere around 76 rpm, leaving users who cared about correct pitch to adjust the playback speed for each record until it sounded right. above all, there was, and still is, general agreement that the diamond disc system produced the clearest, most 'present' sound of any non-electronic disc recording technology.