Why the need for a TT PSU ?
Rega belt-drive turntables are using AC synchronous motors. The speed of an AC synchronous motor is dependent on the frequency (50Hz or 60Hz) of the power supply which means any fluctuation in this frequency is going to affect the speed of TT motor and thus the sound effect of the turntable.
Basically when we desire a stable power supply with very low distortion to run our turntable , a TT PSU which uses a crystal locked low sine wave distortion generator will help to do the job. The TT PSU will bring about better frequency stability and thus sonic improvement to our system especially if the power supply for our location is not clean.
Rega outborad power supply, TT PSU
The Rega TT PSU outboard power supply developed for Rega P7, is also offered as option to P3-24 and P5 since both of them are using 24V AC synchronous motors too.
On this TT PSU, there are two speed selections (33 and 45 rpm) with a simple push button. But other than these two specific speeds, it's not user adjustable to slightly higher or lower speeds should your TT runs slightly faster or slower.
Clearly, for earlier models of Rega turntables (e.g. Planars,..., P25) with 230V or 110V motors, this TT PSU cannot be used directly. You must first upgrade its motor to 24V motor before it could be interfaced with the 24V output of this TT PSU.
At this point you may ask : is TT PSU a necessary upgrade? I would say it all depends ...
"The TT PSU, an optional outboard power supply originally developed for the Rega P7 turntable, produces a stable voltage, synthesized by a quartz oscillator, that drives the motor more precisely. It also permits convenient pushbutton selection of the P3-24's two speeds (33 and 45rpm). It's not retrofittable to the original P3, unfortunately.
So it depends on if you are comfortable with the condition (stability) of power supply in your area or if you would like to enjoy the benefit of easy switching between 33.3 rpm and 45 rpm by a push button instead of manually adjusting belt positions on the pulley (in the case without a TT PSU); the belt remains in 33.3 pulley slot with the Rega TT PSU.
Gandy told me that the TT PSU offers a "small improvement" that can't be quantified. "It's not enormous," he admitted, adding that the better the incoming electricity, the less noticeable will be the sonic improvement........."
The choice is yours.
Take note there are two versions of Rega TT PSU:
i) 50Hz TT PSU
This is supplied with all P7 turntables (P7 uses 24V, 50Hz motor and a 50Hz pulley). It is also for the upgrade of any 50Hz turntable with 24V motor( e.g P3-24, P5 ).
ii) 60Hz TT PSU
This is for the upgrade of 60Hz turntables with 24V motors. This US version TT PSU cannot be used with P7.
Read more on >> Other choices of TT PSUs' .....