Glad I could help.
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.
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- 43 posts total
If your using tubes from the previous owner you have no idea how many hours they have on them. I would say replace all the tubes and go from there. I bet that solves your issue. Others commented on a possible DC Offset issue but this usually manifests itself as a humming from transformers in your equipment and not a sound through the speakers as you describe. Before you do anything...replace the tubes as that to me is the most obvious cause.
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@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?
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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. |
- 43 posts total