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Need Help with Hum

I have a Krell 400cx, Krell KPS-25sc, Musical Fidelity Tri-Vista SACD, CAST cables, Von Gaylord Chinchilla ICs, Siltech Power cords, Siltech speaker cables, Rotel power conditioner, JM Lab Mini-Utopia, JM Lab Sub.

The system was working perfectly; not a spec of hum, dead silence.
I installed separate 30 amp and two 20 amp lines for the system, Hubbell outlets, and ran the wires below the floor to the outlets. IT all works but now the system has a faint hum but only when the Krell KPS preamp/CD is on.

Can anyone help me as to a starting point to diagnose the problem?
I am most appreciative. The work was done by an electrician who specializes in these kinds of home-tech installations and will also try to address it but I thought I would also ask all for ideas.
huntermusic
7 responses Add your response
kr4's avatar
kr4
3,648 posts
 
If the components which were once on the same line are now on separate lines, there are at least two issues which might contribute to the problem you have. First, the separate lines, due to line length/configuration, might have slightly different ground potentials. Second, one of the lines, probably the one with the pream/CD on it, is connected close to another line in the box which is throwing out some noise.

Kal (not a licensed electrician)
kana813
956 posts
 
Float/lift the ground connection on the Krell KPS preamp/CD with a cheater plug and see if the hum goes away.
If does than check the wiring as Kal suggests, if it doesn't, check and make sure the hot & neutral on the AC
line feeding the Krell KPS preamp/CD are not reversed. Most hardware stores sell a inexpensive devices for checking wiring.
darrylhifi
498 posts
 
I do agree with the above, but also I found that sometimes if your external power cords are laying in a certain position, perhaps too close to a component, or speaker cable or interconnect, that also can cause a hum. Also still keeping your digital and analog seperate , sometimes the order in which the plugs are in the outlets can have an effect. As I said I do not disagree with the above, but Ive had a few hums drive me crazy and this was a solution.
huntermusic OP
76 posts
 
You guys are great. I printed out all your suggestions and will discuss with the electrician. I will only fiddle with wires myself as a last resort. Thank you so much. This is why I love this sport.

h.
32gwizae38
1 posts
 
Plug everthing into same outlet, hum will go away.
warnerwh
539 posts
 
The polarity checker for checking to make sure the wires are correct only costs 5 bucks and you just plug it in, I'd do this to make sure they are right. Besides you can check the other outlets in your house while you're at it. I had a similar issue and it was just that my wiring mess behind my system needed to be better organized.
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