2. analog
  3. 1235221564

Garrard 301 & Thorens TD 124 voltage

Hi all,
I have a few questions and hope you can answer for me:
1. My Garrard 301 , which runs on 120V and has 60Hz pulley, still run fast with the speed adjuster turned all the way down. Beside having the diameter of the pulley reduced, is there any other way to correct the speed problem? Would reducing the voltage or altering the main frequency have any useful effect without compromising the torque of the motor?

2. With the Garrard 301 and Thorens TD-124, does running these decks at lower voltage (100V/60Hz vs 120V/60Hz) yield any benefit (ie. less motor heat/vibration/wear) without compromising sound quality and/or damaging the decks?

Thank you very much in advance.
jaytea
quiddity
119 posts
 
Both these decks use shaded pole motors which are a form of asynchronous induction motor. Like all such, some of the power supplied is used to induce the magnetic field in the rotor.

The rotor field is induced by relative motion (slippage) between the rotor speed and the stator field speed. The stator field is synchronous with supply, so the motor must run at a lesser speed.

The greater the load on the motor the greater the slippage. The lower the voltage supplied, the greater the slip for a given load.

Altogether this means the motor speed depends on the supply frequency, the voltage and the load.

Exactly where in this continuum you end up is a matter of taste. For a long time I used 53Hz, 110 V and the brake fully on (mine is a 50Hz pulley) but I'm now playing with other parameters not available on a normal power supply so that will change.

Mark Kelly
jensmunk
20 posts
 
My bad, I did mean asynchonous and not synchronous.

I suppose another option is to get ahold of a variable frequency drive. These are used to control the speed of pumps etc..., but if a small version could be found you could easily use it as your motor speed controller. Esssentially it allows you to control the voltage frequency, and hence the motor speed.
jaytea OP
78 posts
 
I think the Garrard was designed to run on either 50 or 60 Hz with appropriate pulley (and of course, appropriate voltage). I replaced the 50Hz pulley with a 60Hz one..but it still runs fast. I guess the dimension is not correct. Will try another one soon.
pocketchange
19 posts
 
I (on occasion) have noted some of the belt sellers are supplying units with too large a diameter (belt), which will cause adjusting the platter speed to not be possible. Typically, platter speed that has been adjusted to its slowest possible setting will continue to be too fast.
If you have a 1/4" belt, replacing it with a correct (smaller) diameter OEM or [equal] correct diameter belt should return the pitch control to allow having a functional adjustment. A larger than correct size belt will ride on the outer portion of the pulley(s) [just] enough to increase pitch too much to be adjusted properly.
More to discover