Ground loop hum

@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

+1 

That would explain why when the Rogue preamp was set to another input there is no hum. Phono ICs are not shielded and are picking up EMI from a near by non shielded power cord or some other EMI producing AC source.

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@kavakat1 

A ground loop hum means there is a difference of potential, voltage, between  two AC ground points. Result 60Hz current traveling in the ground loop circuit. Result 60Hz hum.

How did you verify it was the TT causing the ground loop? Disconnect the TT ICs from the  Rogue preamp and the hum stopped? 

@kavakat1 said:

Only Jim’s when preamp is set to the turntable.  O other inputs hum. 

I don't think your problem is caused by ground loop. If a ground loop, It should hum even when the preamp is switched to another source input if the TT is connected to the preamp.

Does the hum sound like this. 60HZ hum 

Does the Rogue preamp have a built-in phono preamp? 

What model Technics turntable do you have?

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just tried grounding phono preamp to rogue preamp’s cabinet. No luck.

I assume the TT tone arm is grounded to the phono preamp ground terminal.

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So a ground loop hum must be heard no matter which source is playing thru the preamp? Is that correct?

The 60HZ ground loop 60Hz current is carried through the ICs, through the signal grounds of the equipment. A difference of potential, voltage, must exist between at least two points for current to travel in a closed circuit. Therein ground loop.

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Did you try another Line level input on the Rogue preamp?

Does the TT use a 120V 3 wire grounding type cord and plug? If so, unplug the cord and plug from the wall outlet. Check for hum.

Does the hum sound like this?  60HZ hum . 

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The 60hz noise goes up and down with volume knob.

Does it sound like this?  60HZ buzz

Musical Surroundings Phonominal II+ phono preamp.

Lots of slide switches on the back of the unit. Are they set set correctly? Is the Rogue preamp Line level input specs the same as the NAD. Would the phono preamp switches need to be set differently? Is the gain output signal voltage to high for the Rogue preaamp’s Line level inputs? Settings ok for the NAD...

I assume the power supply for the phono preamp is a two blade wall wart or similar. Wall outlet equipment ground is not used.

If unplugging the TT power cord from the wall outlet did not stop the hum. For a test, eliminate the phono preamp and plug the TT RCA ICs directly into the Rogue preamp Line level inputs. Check for the  "60hz noise".   

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Where is the phono preamp located, distance from, the Rogue preamp and the Aesthetix Atlas power amp? Try moving it, increasing the distance from them. 

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@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...

@kavakat1 , Great!

Best regards,

Jim