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Hum with Ypsilon MC26L SUT that goes away with touching

I need help solving the hum problem.

Ikeda Kai cartridge -> Ypsilon MC26L SUT -> Ypsilon VPS 100 -> Cary SLP 05 -> Cary CAD 211FE monoblocks -> KEF Blade.
ICs between MC26L and VPS100 Stage 3 concepts RCA
ICs between VPS100 and  Cary SLP 05 Stage 3 concepts XLR
Cary SLP 05 and Cary monoblocks Shunyata RCA
Cary monoblocks to KEF Blade Shunyata speaker cables.

Connected ground from tonearm phonocable to SUT grounding post ->I hear 60 hz hum
Connected ground from tonearm phonocable to SUT grounding post + connected  SUT grounding post to VPS 100 ground ->I hear 60 hz hum (slightly decreased)
Connected ground from tonearm phonocable directly to VPS 100 ground (I read in the forums to try this) ->  I hear 60 hz hum
If I touch the body of SUT (metal) with one hand and touch the metal frame of the rack that sits directly on the floor, the hum disappears in all the above situations.

I used two shorting RCA plugs into input loading of SUT with tonearm cable connected to input-> No Hum 
I used two shorting RCA plugs into input of SUT without tonearm cable-> No Hum
I used two shorting RCA plugs into output loading of SUT -> No Hum

Any help in solving this hum problem is greatly appreciated.

Thanks
Kanchi
kanchi647
kanchi647 OP
70 posts
 
Update:
the hum disappeared after I replaced the Stage 3 concepts analord  interconnect from SUT to Ypsilon VPS100 with Ypsilon interconnect.
i also made my own IC using helix design from http://www.image99.net/blog/files/category-002a002a-the-helix-image-interconnect.html
and the Hum disappeared.
can anyone explain why the hum disappeared with just changing the IC?
 Thanks 

uberwaltz's avatar
uberwaltz
13,381 posts
 
It's already been mentioned but very likely one of the internal RCA connection on those ic was broken.
Had it happen myself.
Open them up and take a good hard long look at soldered connections.
At least you have solved the mystery!
lewm
13,702 posts
 
Also, many audiophile single-ended, RCA-terminated ICs are built such that the shield is only grounded to one end.  The manufacturer will typically mark the cable for polarity. In such cases, it could make a difference which end is connected to the input vs the output side, in terms of hum and noise.  I take it that BOTH the Ypsilon IC and your home-made IC cured the hum problem.  Did you connect the ground conductor and the shield to BOTH ends of the home-made cable or just one?
kanchi647 OP
70 posts
 
@lewm my home made IC doesn’t have a sheild or ground conductor. Neither does the IC made by Ypsilon. The Stage 3 concepts IC has a ground conductor and I tried multiple configurations which had hum- including connecting only one side, both sides, none, directly connecting the ground of stage 3 to the TT phonocable and VPS100 and bypass SUT.
lewm
13,702 posts
 
Signal ground is essential. Shield is optional. If there is no connection between one unit and the other via ground for the audio signal to travel, then you would only have one single piece of wire. In my mind, that would not work at all, but is that what you Are saying you have?
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