2. misc-audio
  3. 174831-87123

This 60 Hz hum is driving me crazy

I just got a new to me, Prima Luna Prologue Premium Integrated tube amp. Sounds great, but there is a "ear to the speaker" 60 Hz hum. Hum sounds the same if I adjust volume +-/  The only thing I have connected is a Parasound Zdac.  Speakers are Rega RS1 Here is what I have tried:

1. I disconnected the Zdac so it was just the PL connected to the speakers with no other inputs. Hum still there.

2. While Zdac still disconnected, I use a 3-to-2 prong adpater to determine if its a ground loop.  Still there.

3. The outlet is a new one added from our remodel.  So I used an extension cord and plugged into an original outlet to see if the electricity was "dirty."  Hum was still there. 

Now here some possible culprits.  

* The stereo is perhaps set up in the smallest man cave in California.  The speakers are about 2 feet away from preamp.  I will try moving speakers further. 

* I am using crappy Amazon 12 AWG cables.  I have some better ones coming from Morrow Cables. 

* The stereo is in front of the panel that our internet wiring comes in through (I am in a condo complex).  There is no wireless there, but perhaps I should set up system somewhere else to try.

* I am using the tubes from the previous owner...do I just buy a set of new tubes?  

Is there anything else I should try?  Thanks in advance.

 

comedyzen

Showing 2 responses by paradisecom

paradisecom
379 posts
 

I had a hum years ago that I couldn't get rid of, until I removed the outlet from the wall.  It turned out that the ground wire, which is bare, was just barley touching the hot lead screw terminal in the box.  I just rearranged the Romex in the box slightly and the problem was gone.

paradisecom
379 posts
 

Another grounding issue I had was from the cable TV box. There was a splitter on the outside of the house, which needs to be grounded and it was, to the steel conduit/ main breaker panel just above it. But, that grounding clamp and steel pipe had been painted so it wasn’t making a good bond. The resistance from the splitter to the pipe should have been 0 Ohms, but it was measuring about 10 ohms iirc, which isn’t much, but it was enough to cause the cable box to hunt for a better ground inside the house, inducing some hum. Once I cleaned everything with a wire brush on the outside of the house and got a good bond measuring 0 Ohms, the problem was solved.

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