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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
lewm
13,589 posts
 
If hum does not go away when everything is grounded to everything,  start removing ground wires, one by one.  But it does seem your SUT wants to be grounded to something, and you are already grounding the tonearm to the SUT and the SUT to the phono stage, correct?  Finally, you have several pieces of gear in your phono chain.  Are all the items plugged into the same AC source (same wall socket)?  If not, they should be. Small AC voltage differences in grounding of one wall socket vs another, even in the same room off the same circuit breaker, can cause hum.
oldhvymec
5,101 posts
 
Might want to clean the contact points on the ground at the TT.

Remove it clean it reinstall and tighten it. Clean all surfaces on the grounds.

Dirty contacts don't have to look green to have a bad or lose contact. Loosen and retighten stuff.

Plug and unplug to clean the contacts. Kinda of a crude way, but quick. Alligator clips and wire, for testing. Jumper leads. Keep them in the tool bag, ay?

Want to get real picky. use a DMM, and see if there is a voltage difference, between the Turntable and Preamp, at the chassis
GROUND. If there is a difference, there is a good chance they lost contact, at the ground wire, either end.  Check for continuity, in the power off position, between chassis, CLEAN or repair the wire as needed.

Happy hunting

Regards
three_easy_payments's avatar
three_easy_payments
2,097 posts
 
@kanchi647   

Are you suggesting to connect another wire between ground post from VPS 100 to Cary SLP 05? I do not see a grounding post on SLP 05. I'm saying ground your SUT to something. 

In my case I have a grounding post on my SUT and also one on my phono preamp.  It's unlistenable without this wire in place.
kanchi647 OP
70 posts
 
@lewm all my components are connected to Shunya V-ray which has 8 outlets.

Yes,  I am already grounding the tonearm to the SUT and the SUT to the phono stage. 

Is there a way to connect the ground from Phono stage to pre-amp and amps? Just touch the body of the amps? How do the wires stay in place?

@stringreen I used a junk wire and connected the SUT and made contact with the metal rack. Hum did not go away. It only goes away when I place my palm on the metal rack and have good contact. How do I make good contact using the wire to the metal frame? I will get some wire from lowes tomorrow.

@oldhvymec the contacts look clean. How do I clean the contacts? Is there a solution you recommend?

Thanks for all the help
oldhvymec
5,101 posts
 
Clean means shiny metal, to shiny metal. An eraser is good on copper or brass. A small wire brush (tooth brush size). I use carbon steel, brass bristle, and nylon. Wipe the surfaces, with isopropyl, contact cleaner, or a little WD 40 on a Q Tip. It will remove all the moisture and put a light protective coat. Screws with securements (nuts, wing nuts, the like) just work them back and forth...and a light lube, Wipe off the excess.

LOL never found a squeak I couldn’t stop...

If you’re worried about scratches. Tape off the work area with painters tape before you start, ay..

BTW, Nice Preamp.. Really one of my favorites..Lot of craftsmanship there.. That has an umbilical cord. right?
might want to unplug that and plug it in a few times.. clean the contacts... The UC.. Just to make sure..

You’ll get it..

Regards

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