Motors that run on AC line voltage spin at a rate determined by the input frequency. But DC motors and those controlled by phase-locked-loops and other feedback mechanisms aren't dependant on AC line frequency. So the motor speed of a turntable may or may not be affected by line frequency, because it depends on how the unit is made.The Technics SL1200 uses a quartz locked servo drive, so speed is not affected by line frequency. It is a very good speed control method, in my opinion.