Pro-ject Speedbox S is an excellent upgrade to 16V AC turntables
AC motors are designed to sync to the power supply frequency (50Hz here in New Zealand). That frequency can change depending on regional power supply issues such as very high demand in Winter etc.
The Speedbox creates an accurately timed signal using the a Quartz oscillator (Like in a digital watch) so that the speed of the turntable motor is perfect.
This will not work on Pro-ject's newer DC powered turntables, where the timing cannot be changed at all.
The Speedbox will not work on the following turntables:
For all other models, feel free to check with us to ensure you actually paid for!