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 7 responses by dill

dill
2,574 posts
 

Well, it is not the speaker cable. Have you tried switching between the 4 & 8 ohm taps?

dill
2,574 posts
 

Could be a loose ground inside the amp. If you only can hear it when your ear is next to the driver and doesn't increase with gain, I wouldn't worry about it.

dill
2,574 posts
 

"but at this level of hi-fi I have certain expectations"

Then you you need to serious about the size of your room. I don't think you will get satisfaction inside a closet with any setup other than headphones.

dill
2,574 posts
 

Get one of those cheap yellow outlet testers at Home Depot and see if the new outlets where wired correctly.

dill
2,574 posts
 

For tubes I suggest Jim McShane or Brent Jessee. Both have websites and are good sources for tubes. Jim for good prices, Brent for the best.

You might have a ground issue inside the amp. I had one in my phono stage that was fixed by removing some paint from under the chassis ground wire. There was not enough bare metal exposed to make a good ground. The paint was acting like an insulator.

dill
2,574 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.

dill
2,574 posts
 

That is a good idea steakster!

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