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Phoenix Engineering speed control

I purchased the Phoenix Engineering speed control for my VPI Classic 3. I purchased  the bigger power supply and the tachometer combination of the speed control.  I notice that I can hear a steady hum coming from the speakers when the speed control us turned. The hum is constant and will not vary if I turn up the volume on the Preamp.  But the hum goes away when I turn the turntable off. The hum return when I turn on the turntable again. I even in unplugged the interconnect from the turntable, but it make no difference.  Does anyone with the Phoenix Engineering speed control experiencing the same issue?
almandog
almandog OP
141 posts
 
I will call them tomorrow. 
I am listening to some records now and I can still hear the hum before I start the record.  I disconnected the Turntable from the Phoenix Engineering power supply and the hum disappear. So the Phoenix is definitely is causing the hum. I even put the Phoenix power supply on the floor away from other power cords, but it made no difference. The display on the Phoenix is working fine: 33.3 RPM on the main display and 33.334 on the racometer. So it's seems to be doing the job. But the hum from the speakers is a mystery. 
sbank's avatar
sbank
3,378 posts
 
It's probably a ground loop. Do the table and/or the Phoenix have a ground wire? Try a cheater plug. Experiment with whatever ground wires there are between them and share the results with Phoenix when you call them. Cheers,
Spencer
buffyjames
38 posts
 
I agree with sbank....its a ground problem. If you use a cheater, only use it to confirm a ground issue...don’t keep it in the system....they ruin the sound. Use a voltmeter to see that all wall plugs are wired correctly. This can be very tricky to find.  I would get in touch with both Phoenix, and VPI and see if they have suggestions.  If I were in a betting mood, I would say that Harry has the answer.
sbank's avatar
sbank
3,378 posts
 
Harry usually does! 
almandog OP
141 posts
 
Yesterday i tried the Cheater plug and it worked. It was definitely the Phoenix Engineering power supply causing the hum.  I don't want to use a cheater plug in my system so I will move things around this weekend to see if I can get rid of that ground loop.
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