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 3 responses by russ69

russ69's avatar
russ69
3,573 posts
 

I'm too lazy to type the whole path of isolating 60hz hum, but if that hum is "ear to the speaker", quit doing that. 

russ69's avatar
russ69
3,573 posts
 

So even from a distance, I can hear it in between songs.

If you hear it from your listening position, it’s got to get solved. P.S. I have never had a hum issue I could not solve. First step is isolating the problem. Isolate it, then I’ll give you some ideas.

Edit. If amp hums with just the speakers hooked to it, it's the amp. Tubes are always suspect. Is it in both channels? Did it always hum? You might need a call to Upscale.

 

russ69's avatar
russ69
3,573 posts
 

(reduced about 80%)

My main tools for finding a hum are a cheater plug and a pair of ground breaking RCAs. I take all my gear and put it on the floor and hook up one item at a time. I can usually find the culprit. Then I can work on that one piece of gear and find the solution. One of the toughest ones was an unpolarized two prong plug on a preamp. If it was inserted into the wall the wrong way, it would hum. The other way, no hum. Voila!

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