Ground loop hum from Turntable


Not sure what is causing this but, i took home a Rega P3-24 to demo, hooked it up to my Plinius 9200 and was getting a loud hum. I noticed Rega does not include a ground wire on there interconnects. My dealer indicated that the ground is done internally. I am limited as to where i can put this table. I have a Billy Bags AV component rack and all my gear is on this rack including my TV. I assume this hum is being picked up from the other components. Any suggestions as to what i can do to greatly reduce or elimiate this hum. Thanks for your input.

System:
Plinius 9200
Naim cdp 5i-2
Speakers Dynaudio Focus 140's & 200c center
Sony dvp 9100es
NAD HT receiver T762
Cables All FMS
TV Sony XBR 960
brian27b
First connect only the TT to the pre-amp and amp only (no other components). If the hum continues try a cheater plug on any power cords that have 3 prongs starting with the TT then the pre followed by the amp. I had a hum from my cdp and lifting the ground (3rd round prong) from the power cord fixed it. Cheater plugs can be had at almost any hardware store. That being said I do not recommend cutting of the ground from the power cord especially if its an upgraded cord (then do it or have some one do in the connector as not to devalue the cord). That way you can put it back if you should ever decide to sell it.
Cheaters are ok to test for ground loops, but they sound awful. Don't use them as a permanent installation
If your P3-24 has the outboard power supply, try moving the power module as far from the TT as the connecting cord will allow. (That's the hum-avoidance recommendation in the manual that came wilh my P9.)

If practical, you might also try plugging the electrical cord into a separate outlet from the other components.
You mention the TT is near or next to the TV. This might be the culprit. Most newer TV's are always on, even when in the off position and generate EMI which your TT might be picking up. You might try unplugging the TV and see if the hum goes away. Just a thought.
Wow! Many responded but forgot to address the real issue.... The Rega uses a grounding scheme where in only one ground (not the right term, it should be negative phase) is common between + of both L&R signal. If your phono preamp is not configured the same, it may result to a hum.

What to do? Try to connect the negative phase of the L & R signal input at the phono preamp together or disconnect one of the ground from the input IC's. Also, try to ground the body of the arm to the phono preamp ground.

Assuming that the one you are having is really a ground loop problem and not anything else of course. The posters above mentioned isolating the position of the table and the phono preamp from the rest of the equipment. That is a good suggestion in order to find out if youare picking up RFI or really have a ground issue.

I do not know a lot but I experienced the same thing using my Origin Live Silver and rega 300 arm before.

Goodluck!
If you don't find the culprit with the above suggestions you can perform surgery on your Rega so that the arm ground is separated from the cable ground. This may help. You have to remove the rubber plug at the bass of the arm, under the plinth, and you'll see the layout and can reconfigure it with a separate ground wire. There is a step by step guide somewhere online that walks you through it. Rega does a lot of things to make their tables no brainer, for those with no brains. ;-)