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Hum in my system; its the turntable R and L interconnects. Huh?

Pioneer PL-570 reconditioned turntable

EAR Phono Box

Cambridge Audio Integrated amp

DALI Floorstanders

I have a very pronounced "Hum" in my system, sounds like a 60cycle hum. I tried all the troubleshooting steps; it originates in the EAR, which has just recently been serviced and has new Goldline tubes. But here is the kicker, if I disconnect the R and L TT interconnects the hum cuts out and I get a fine white noise sound of much less volume. The TT produces the hum in the system even if the TT is unplugged from the wall receptacle. Removing the ground wire from the TT to the EAR has no effect. I can place my ear on the EAR case and hear nothing, dead quiet. A fault inside the TT?

jereeb
jereeb OP
7 posts
 

Update: I took the EAR over to my friends house and tried it in his system. The EAR was quiet. So it's for sure originating in the TT. Odd that the TT will generate this feedback even if its not plugged in. So its not being generated by energy in the TT, it must be related to a internal wiring fault or the picking up of interference. He has an oscilloscope and has offered to hook it up to the TT to look at the sine wave. I'm not an electrical engineer so not sure what I can learn from that. 

I also ran a ground wire from the EAR to the amp: no change. 

I have not tried the TT in another system, or a different TT in my system. More to follow. Thanks to all of you that have shared your expertise. It's a journey... 

1happyman's avatar
1happyman
86 posts
 

Had the same problem. 

Make sure your turntable is plugged into the same outlet as the phono amp. 

 

 

jereeb OP
7 posts
 

Thank you.

I did that and it did not correct the issue.

My experienced audio friend took one listen to the system and said its interference being picked up by the TT R & L cables. BTW: the interference is there even if the TT is not plugged in. 

I have for sure narrowed it down to the TT as the source. 

atmasphere's avatar
atmasphere
12,116 posts
 

@jereeb The problem is the ground wire on the phono isn't making a connection. So the thing to do is run a wire from the tonearm base (assuming its metal) to the chassis of the EAR.

If there is a screw securing the arm to the plinth of the turntable that is the ideal point to put the wire.

The RCA cables and cartridge connections are obviously OK. Its normal for the 'table to not be plugged into the wall and have this happen if the ground wire has an open connection.

jereeb OP
7 posts
 

Well it wouldn't be an aesthetic fix, but I could run a test wire from the tonearm base plate to the EAR based on your suggestion. Then if that corrects the problem I could flip the table over and make up a connection from the underside. 

Thanks so much for the suggestion!

 

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