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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
dill
2,525 posts
 

My phono stage is a separate, stand alone unit plugged into an integrated amp via interconnects and is about 1 1/2'away from the amp. The ground wire inside was insulated by the paint. I took off the ground wire, scraped the paint off and bingo, no more hum.

Post removed 
dill
2,525 posts
 

That is a good idea steakster!

comedyzen OP
15 posts
 

Got the DC blocker. Was excited because I turned on amp and no buzz. Walked away and came back a minute later. Hi Buzz!  Didn’t work. Got the BuzzX coming in too. Doubt it will work but glad Amazon makes it easy return. 

4krowme's avatar
4krowme
542 posts
 

Separating the wheat from the chaff in an advice column can be helpful. No offensive intended here. Working mostly with DC circuits and some AC circuits, I found out a lot of lies that sounded right but would lead you in the wrong direction. >>>>"Ground is ground the world around"<<<< was one of my favorites. Sounds catchy and true, but no, it isn’t.

I am sorry that the DC blocker didn’t work for you. Would have made things simpler. One thing that you mentioned was that there is Still Hum when using the amp on a different circuit in the house. That definitely points to the amp at this moment. Replacing the tubes may be a good idea, yet I would be inclined to start only with the rectifier tube if the amp uses one.

Try to isolate One Thing at a Time. That is what we did in my job, and though it might seem tedious, it won out in the end... most of the time. As others have said, it can be difficult to find a hum problem, but at least there are a few things that you can do on your own.

 

I look forward to following your progress.

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