I just ordered a new Hurst motor (3203-001) for a VPI HW-19 clone but the noise/vibration is terrible. Since Hurst does not take returns (shame on them) how can I reduce the noise? Unlike the motor for the AR, where you can adjust the shaft "slop" by tapping the rotor/shaft bushing tighter to reduce the endplay, this looks like it has a wavy washer/snap ring? Also the there is slop between the outer cover and top plate, where a rubber washer/o-ring is in the gap between the two. Mine is loose.
I used to use this motor a lot in the past. Now that these are built in China, the quality is very poor. Sucks that a non-returnable $100 motor is this bad.
I used to use this motor a lot in the past. Now that these are built in China, the quality is very poor. Sucks that a non-returnable $100 motor is this bad.
First check the phase capacitor. If you look at the voltages to each of the motor windings on a dual input CRO they should be exactly 90º apart. If not, you need to adjust the value of the phase capacitor until they are, or the torque profile will not be as smooth as it should be. Many synchronous motor driven turntables that I service need the phase capacitor tweaked, often by adding a small shunt capacitor to get it just right.
I suspect that a motor rated at 10W has much more torque than you need. Linn and Rega motors are about 2W. The greater the torque, the greater the cogging and vibration. If you have a variac you can reduce the supply voltage until you find the smallest supply voltage that will reliably start the turntable platter. Then you can use a suitably sized series resistor as a voltage dropper to run the motor off mains. I just did a turntable yesterday with an Aeropax motor meant to run at 110V. The optimal for vibration on a Rega Planar 3 turned out to be 70V, needing a 15kΩ series resistor in this case, which was enough to drop noise picked up by the cartridge on blank grooves from clearly audible and verging on annoying, to inaudible.
Finally you might find it necessary to balance the two windings with a small series R in one of them. Yesterday after setting the lower drive voltage I experimented with resistors from 150Ω up to 390Ω first in one leg, then the other, listening with a stethoscope on the motor mount, but with the motor I had I could not improve the noise and vibration any further.
BTW many electronic motor controllers for synchronous turntable motors deliberately drop the running voltage after a few seconds after startup to reduce vibration.
I suspect that a motor rated at 10W has much more torque than you need. Linn and Rega motors are about 2W. The greater the torque, the greater the cogging and vibration. If you have a variac you can reduce the supply voltage until you find the smallest supply voltage that will reliably start the turntable platter. Then you can use a suitably sized series resistor as a voltage dropper to run the motor off mains. I just did a turntable yesterday with an Aeropax motor meant to run at 110V. The optimal for vibration on a Rega Planar 3 turned out to be 70V, needing a 15kΩ series resistor in this case, which was enough to drop noise picked up by the cartridge on blank grooves from clearly audible and verging on annoying, to inaudible.
Finally you might find it necessary to balance the two windings with a small series R in one of them. Yesterday after setting the lower drive voltage I experimented with resistors from 150Ω up to 390Ω first in one leg, then the other, listening with a stethoscope on the motor mount, but with the motor I had I could not improve the noise and vibration any further.
BTW many electronic motor controllers for synchronous turntable motors deliberately drop the running voltage after a few seconds after startup to reduce vibration.