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 12 responses by comedyzen

@russ69 haha...well, as mentioned, I am in the smallest man cave ever. Its a converted walk in closet turned office/stereo room.  So even from a distance, I can hear it in between songs.  I know its not too big of an issue, but at this level of hi-fi I have certain expectations...otherwise i would just get a SONOS.

@dill Agreed and thats the goal.  Looking to move next year but for now, the closet office is the only place I can set this up.  I have one of those....what do you call them again, oh yea, a wife, that doesn't want so much stuff in the living room.  Nor do I want it accessible to my 6 year old who loves to push buttons beyond their limits.  @4krowme  I used a plug pre remodel so I assume its on a different circuit.

thanks Coach.  This is great info.  Going to try a few more things but will def add this to the list if all else fails.

Now that I think about it, both plugs I used were new ones from remodel from contractors who I would never use again. Hmmmmmm...need to try another outlet...unless they compromised the entire home.

@dill got the little $6 yellow tester (figured it is good to have regardless).  All outlets I have been using were OK.

Also moved the amp out of my mini man cave into the living room and plugged into another outlet....and the hum is still there!!!

I ordered the iFi DC blocker from Amazon to check that next.

My new speaker cables came in too, and no help.

If the DC Blocker fails, I will try replacing the tubes.  Does anyone recommend a solid place for both price and good tube reputation?  

 

Thanks @dill! I will google their names.  There is no phono stage on mine but there is a ground mount on the back for a phone preamp.  To your point:

Talking to someone from Upscale service.  I mentioned that I lifted the ground but he still thinks its a ground loop.  He basically told me to Google it and try other things.  Haha

 

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. 

@steakster I have too much going on to do that but instead, I plan to pack it up and take it into my office (which was built in the 60s) so I hope the electrical there has good grounds.

I knew it wouldn't work, but tried it anyway.  DC Block paired with the Hum Eliminator did not work.  Also notice that the Hum will increase a touch if I turn the volume up.  Is that a 120 Hz?  

Really confused now.  Talking to someone at UA, he thinks its a groundloop and new tubes won't help.  Spoke to a local dealer here and he thinks the tubes need to be changed.  

I am trying everything I can before taking her in to the doctor. 

UGH!!  Fresh set to tubes from McShane...perhaps a slight decrease in buzz, but it's still there.

Looking for Bay Area recommendations for stereo repair.  I don't know what else I can do.

FYI, Upscale Audio was completely useless and the customer service was quite half ass.  I do appreciate that they got back to me, but their replies were very "figure it out or Google it."  Which I did.

Ooooh.  I have LEDs and dimmers.  But I took the unit to my condo complex's main lobby and plugged in there.  Got the buzz.but there are LEDs galore.  Maybe I need to take it to my office that was built in the 60s