SME V STANDARD PROTRACTOR
CARTRIDGE ALIGNMENT TOOL
The SME V protractor achieves alignment by adjustment of a moving arm base. Since there are no slots in the headshell, the cartridge position can not be adjusted at the headshell. In effect, the effective length and offset angle are held constant. As these parameters do not change, the only means of adjusting the overhang is by means of the moving arm base. The three alignment arcs represented here are achieved by holding the inner null point at the IEC standard location for an LP with an innermost groove at 60.325 mm and an outermost groove at 146.05 mm. The outer null points are calculated and fall wherever the numbers put them. In the case of the Baerwald and Loefgren arcs, the outer null points are within a few hundredths of a mm of matching exactly what would be calculated if the cartridge could be adjusted at the headshell. As can be seen in the drawing, the Stevenson arc utilizes an outer null point that varies significantly from what would be obtained if the cartridge were adjustable at the headshell. The SME V arm is designed to use the Baerwald alignment arc for a standard alignment.