Another headache of Rega turntable speed .... 50Hz/60Hz problem...

"beauties on parade..."

When we travel from one part of the world to another, we are always being reminded to pack along a voltage converter for our electrical appliances. Electricity power supply differs around the world in voltage and frequency. This is nothing new to us.

Yes, a voltage converter will suffice - either 110V to 230V or vice versa....

Never occur to us frequency of power supply would be an issue.

You only realize this when you start spinning Lp's on your Rega turntable! What has gone wrong? It's not spinning correctly! But I have not forgotten to use a voltage converter.....!

Where is the trick? Is it the motor?

Bingo! The motor! The speed of the ac synchronous motor for Rega TT is dependent on the frequency of the power supply.

Take a look at the Rega motor (e.g. Premotec 31813 series) : we notice that the motor windings are designed for dual voltage so that the same motor can be used for both 220V and 110V turntables. The difference is : a 6.8K ohm resistor is added in series for operating with 220V supply. Take note also different phasing capacitors are used for different frequencies.

Motor used for both US and Europe TT's

Motor connections for 110Vac circuits

Motor connections for 220Vac circuits

(Motor connections data sheet from mclennan.co.uk)

The pulleys

At 50Hz and 60Hz, the motor speeds are respectively 250rpm and 300rpm. To adjust for this speed difference for different regions, pulleys are of different sizes (smaller for 60Hz) whilst the sub-platter size is kept constant. 

This explains why a US version TT cannot work properly in Europe even if a voltage converter is used or even alteration has been made to the voltage circuit. We've overlooked the fact that motor speed is dependent on pulley size.

Turntable is a bit more "fussy"(like us) .... isn't it?

What if I have a TT PSU?

This would not be a problem if you are already running your system with an external power supply (TTPSU). You may be curious why is it so? This is because TTPSU is already crystal-locked to a fix frequency with a matching pulley (e.g 50Hz PSU/50Hz pulley), therefore the frequency of the main power supply would not affect your motor speed at all. You only need to get a 24v wall wart (AC adaptor) which suits the local voltage for your TT.

<< back of Rega TTPSU

Headaches solved

By chance I came across someone who purchased a Rega TT in Hong Kong (230V/50Hz) which refused to perform when brought back to South Korea (230V/60Hz). In this case, voltage is the same; it's the "50Hz/60Hz" problem.

I also encountered another even more interesting case in Brazil (one of the few countries in the world to use both 110V and 230V for everyday appliances). Moved within Brazil, but happened to be a region of different voltage/frequency, a poor friend of mine could not get his turntable speed right. Again it's "50Hz/60Hz" problem.

I told them where the trick is ....

Glad to know that now they are happily spinning Lp's on their turntables after changing the pulleys.

"Keep both your 50Hz and 60Hz pulleys, you probably wouldn't have problem spinning your lp's on Rega TT's anywhere (in 50Hz or 60Hz region)." I told them.

Now, not only I know electricity power supply around the world differs, I discover besides 230V/50Hz and 110V/60Hz that's common, we do find places with 220V/60Hz ( like South Korea) and 100V/50Hz ( like Tokyo) .....

And I learn all this because of the little pulley.....

David Kelly is staying in Canada and he has a Planar 2 bought from UK. The 50Hz pulley has been changed to 60 Hz pulley : 

Hello Michael,  I received the package last weekend and now have my turntable up and running.  Your upgrade works very well and I've been having a great time getting the vinyl out. My kids are very interested in this ancient technology.  Thanks for your assistance and the excellent service provided  David Kelly.