Ground loop hum


My technics turntable developed a ground loop hum when I got a new preamp Rogue RP7 and power amp Aesthetix Atlas.  I had a ground wire connected to the turntable and grounded it to each, one after the other when the first had no effect. Neither did the second grounding. It has been suggested I ground it to both at the same time which I haven’t tried yet. Any other suggestions?  I am running the system from two dedicated 20 amp lines. Running Vandersteen Quatro wood ct speakers.  Thanks in advance. 

kavakat1

@kavakat1 

Somehow you have ignored my post above which I believe is your problem.

I could be mistaken, but I think that your problem is that the interconnects between the turntable and phono stage and/or the interconnects between the phono stage and preamp are picking up interference.

If so, insert more insulated interconnects to test.

 

@kavakat1 said:

Something to report. I unplug my phonograph power plug and the hum is still there. What’s that mean. Will move phono to line 3 to see. It’s presently on line 2 and cd is on line 3. Too much fun. 

Like I said earlier in the thread, I don’t believe your problem is a ground loop. 

I assume when playing the CDP, there is not any  "60hz noise".   Correct?

You never answered if the tonearm is grounded to the phono preamp ground terminal screw. If not and floating it will act like an antenna.

What better receiver for the noise than the phono cartridge. Crap will ride along with the analog signal to the Rogue preamp and right out to the speakers connected to the power amp.

(The ground terminal on the phono preamp is connected to the signal ground of the preamp.The tonearm needs to be connected there.)

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@jetter said:

The only time I had a hum that sounded like a ground loop from my turntable was when I was using a set of interconnects that were not properly insulated for turntable use.  Morrow literature made it clear to use their phono specific interconnects for turntable use but I thought I would try my non-phono interconnects anyway and hence the hum.  I then installed "regular" insulated interconnects, and the problem vanished.

Perhaps your new preamp is more sensitive to this.

Try a different set of interconnects.

I think the 60Hz noise is airborne EMI entering  through the phono front end system somewhere. 

How close is the TT, phono cables, and phono preamp from the Rogue preamp? Doesn’t matter what the position of the NAD was. Different equipment. For a test, try separating the TT, phono cables, and phono preamp further away from the Rogue preamp.

@jetter +1

You beat me to the punch, before I posted my above post.

If so, insert more insulated interconnects to test.

I think you mean shielded. The TT phono cables to the phono preamp should definitely be shielded phono designed cables. Jmho...

Are you using or have you tried balanced (XLR) interconnects?

They worked for me when I had an unwanted hum. I never took the time 

to seriously diagnose the cause (lack of patience), I took the advice of Paul

McGowan from PS Audio. 

Jea48

you hit the nail on the head.  Problem resolved with my moving the phono preamp away from the Rogue CB preamp. I had it sitting on top of the Rogue.  You can hear it getting  softer and louder as you move them farther apart and the closer together again.  Thank you all for your insights and thoughts about this problem. As in real estate, location, location, location.  My best to you all. Jerry(kavakat1)