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  3. 159523-46

Getting him in my ARC PH3se phono pre

I use two isolation transformer to hook up all my equipment. 
One has the phono pre, TT motor (VPI Prime) and the speed controller equipment for the TT - 250w.  The other has the preamp, and amp - 1000w. 
I’m getting a hum when I turn up the volume when listing to audio through the TT. Here are the are the conditions it’s happening under:

1. Phono pre must be on for hum to occur. If turned off hum goes away. Obviously, so must amp and preamp Be turned at the same time to hear the hum. 2. Phono pre on, but TT motor off, hum is present. So no music playing. Btw motor is controlled by Eagle and Roadrunner. 3. Phono tubes are new and in good condition. 4. The Phono unit is an older unit, but when I had it connected to another system in another room I did not have a hum problem. 
Not sure where to go from here. Especially since I’m connected to isolation transformers. 
last_lemming
last_lemming OP
632 posts
 
I have done the ground wires to no avail. In fact I have run a ground wire from all the components and tried all kinds of combos. Nothing changes the hum.

i have a Hum X cheater plug and that did nothing either. 
mijostyn's avatar
mijostyn
8,450 posts
 
Last_Lemming, the Grado hum will get louder as the cartridge gets closer to the motor. I would start floating grounds starting with the Phono preamp.
mijostyn's avatar
mijostyn
8,450 posts
 
woops, I see you have used the cheater plug. Remove the positive signal wires from the cartridge.
mijostyn's avatar
mijostyn
8,450 posts
 
If the hum goes away you have a cartridge problem. Is the turntable near anything else that might cause a hum?
mijostyn's avatar
mijostyn
8,450 posts
 
The PH3 SE is a great phono amp and should be dead silent if loaded correctly. It is certainly a keeper. You would have to spend serious money to do better. RAM Labs SLN 6922's are a great upgrade.
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