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

  Could you eliminate the power ground by using a cheap 2 prong wall adapter. Or use an extension cord to power the TT from another circuit ? 

@jereeb Wrote:

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

See here

Mike

buellrider97 and ditusa, Thanks for your suggestions. I read the article and several others by PS.

1. The hum is created by the TT R and L interconnects even if the TT is not plugged it. If fact plugging it in or out makes no change.

2. I tried using a 2 prong; no change

3. I plugged everything into a HT Monster Power HTS2000 power strip I had on hand; no change. I tried eliminating the ground prong on the power strip, no change. The only thing that works is disconnecting the R & L signal lines from the TT. 

I can only guess that it is a fault inside the TT wiring.

Perhaps try running a second ground wire from the EAR to a screw on the Cambridge.

You might also want to try making sure the cartridge clips are tight on the phono cartridge.  Use a needle nose GENTLY and close them down if they are loose.

@jereeb  -  What cables are you running from the turntable to the phono-pre?  Is it possible that they are picking up the 60Hz hum from one of the power cords, the AC wiring in the wall, close by power suppy, etc.  I had a problem once where I was picking up EM interference from a nearby radio station on the cables from my VPI table and the phono-pre.  I could actually hear the radio program/music.  I switched to a set of shielded cables and it went away.

I've also heard, somewhere a long time ago and I don't remember where, that some Grado cartridges are  susceptible to EMI.  Might be complete bs, but might be possible.

Just a thought.

Good tips! I'll try the additional ground wire, dbl check the cartridge clips are tight (pretty sure they are, they were a tight fit going on). The TT cables picking up EM is a suspect as even when the TT is disconnected from power, the hum is there. I am also going to try a different TT later this week.

Did this just start one day randomly? You mentioned your repair prior to this happening. As mentioned above cable shielding was an issue for me. I have a modded Thorens with a Grado Prestige cartridge. When I hooked it up I lacked a good pair of cables so I tried a pair of Anti-Cables level 3 non phono that I had in the leftovers box. The TT is close to my plasma TV and the 60hz hum was noticeable as my ZU’s are high sensitivity. Another random thought is a friend just asked me for advice regarding his vintage Pioneer TT. It’s having noise issues only when the arm is moving from the rest over to the record. Once it hits the record it stops. It’s always something, but yours is definitely interesting. I think we’re as eager as you to know the cause. Regards , Mike B. 

@jereeb   If you are also going to try a different TT, I'd also try a different set of cables, ...any different set of cables.  It could be that one or both of the cables were damaged when you unplugged the EAR out or hooked it back in.  (It happens.)

All good suggestions! The cables from the TT are soldered in place, they can't be swapped. I would consider upgrading the cables if when I try my son's TT in the system, the hum goes away,

I did try different cables between the EAR and the amp: no change. And tried a different input on the amp: no change.

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...