The servo motor system tonearm

Servo systems are noisy, complex, and almost never achieve the desired perfect perpendicularity of the cantilever to a radial line across the grooves. Instead, the stylus zigzags its way across the record, the servo first overcompensating in one direction, then the other. Servo systems by their very nature work only after an error has occurred.

The mechanical-bearing system tonearm

The all mechanical method is the least complicated (for lateral linear movement), but certain difficult problems need to be addressed, like the set up difficulties and the inherent geometric errors.

This arm suspends the playback mechanism directly over the record, placing the vertical pivot centimeters behind the stylus' travel across the record. This creates big problem and even the most minute record warp causes large vertical cartridge and cantilever excursions that result in highly audible "warp/wow" and large changes in vertical tracking angle - VTA.