Strange Noise from PrimaLuna DiaLogue One


I have been the happy owner of a Prima Luna DiaLogue One (the *non* "premium", original DiaLogue) for about 8 years now. I love the thing to death.

My system consists of Sonus Faber Elipsa SE (or "Red") speakers, and Oppo 105, and Nordost cables. Most of my listening is via CD's or my own custom-made server (still using the DAC in the Oppo).

Here is the problem I have been experiencing as of late:  

I am getting a kind of noise coming from the tweeters of when using the PrimaLuna. The noise the same in both speakers and even happens when the amp is on "mute".

The best way I could describe this noise is that it sounds like "interference". A sound similar to what one normally experiences when a cell phone is placed close to a speaker and there is an incoming text message. But in this case, the intermittently "beeping" noise is almost constant. Impossible to hear when playing music, but it can get distracting during silent passages.

I am baffled by this, because the PrimaLuna has been exceptionally dependable, reliable as a rock, and dead-silent as of today.

I tried changing tubes (all of them), turning off my Wi-Fi router (not that it makes a difference, since I live in a condo and there are literally 10 other signals in the air 24/7), I made sure nothing was charging in the house, we do not even have dimmers anywhere... but no luck...

Today, my dealer let me borrow a McIntosh integrated amplifier. I have been curious to try out a solid-state amp, as I believe my speakers (not the last word in efficiency) would not mind the extra juice... With the solid-state amp, the noise is gone! Baffling!

Even if I end up liking the Mc, I will not part with the PrimaLuna, because I love it so much. But I would like to find out why I am experiencing this issue... Any theories as to why this may be would be appreciated.

Thank you all in advance!


beyondarkness
Well, the plot thickens.

Long story short, the noise I described earlier is 100% an FM station that is interfering in my system and overall making my life miserable.  

I can now hear it on the McIntosh as well.

The reason why I was *not* hearing it before is because I was only using the digital coaxial input on the McIntosh. Since the Mc has a built-in DAC, I was using a digital coax cable from my Oppo 105 straight to the DAC in the Mc, so we are talking about a 100% digital signal path. No noise at all.

But after a few days, I decided to try my turntable...

The FM noise is back. In fact, I decided to see if the noise was also present in all of the analog inputs. And, yes, it is. However, you need to crank up the amp all the way to +/- 80 to really hear it, and I would never listen at those levels. I am normally listening at 38 - 48. So that is why I did not notice it before, and, regardless, it is a non-issue since the DAC in the Mc is really good, so I do not need any of the unbalanced inputs.

But when using one of the unbalanced inputs with my Pro-Ject turntable, the FM noise comes back in full force. It is like literally listening to the station. It is VERY noticeable at around the 50+ volume level. This is with the following signal path: turntable > phono preamp (external) > Mc unbalanced input. The noise is louder on the right speaker, for some reason.

It gets weirder.

I disconnected the turntable, and brought it closer to the amp. I then used a single pair of RCA's to go straight into the Mc's MM phono input. The radio interference was better (ie: less audible... because the turntable was now in a different location). However, the phono stage was really noisy! NOT the FM/RFI noise I described earlier. Just plain old-fashioned "sssshhhhhhhhhhhhhhh" phono noise.

Then, I tried disconnecting everything analog. All I had was my Oppo 105 and a digital coax cable and the speakers, of course. With this set-up, I switched to the MM / MC inputs (again, with NOTHING connected to those inputs) and turned the volume up. At around the 45+ level, there is a lot of noise! With NOTHING connected! And... the MC input is LESS noisy than the MM input.

What a hobby ours is!
You might want to try some RCA "covers" which are metal buttons that fit over unused RCA inputs. Also, are you sure the interference is an FM signal? It may be a CB radio or "Ham" radio signal. It's always something...
Well , at least you know it’s not the PL. You might want to try and move all cables around including power cables. Try to keep them away from each other, or at least at 90degrees. Start with just the pre and the amp. Possible change the position as well. 
Also try some of this http://www.stillpoints.us/index.php/product/ers
ers cloth. Good luck
Thank you all for the input and help. The interference seems to be precisely that: interference, and not the fault of the PrimaLuna after all. The problem simply manifests itself differently in each amp, and not surprisingly the tube amp was more sensitive to it.

Last night, I went out to walk my dog. I normally wear noise-cancelling headphones when I do this because the area we live in is unbearably loud. Main avenue, lots of hotels and traffic everywhere.. A nightmare if you are like me and have sensitive hearing... Normally, I leave my house with music already playing in my headphones, so by the time I get out I do not notice the outside world as much. But this time I forgot to turn my portable player on, so the headphones were working in noise-cancelling mode without any music playing through them. As you know, noise-cancelling headphones actually have microphones built-in. Lo and behold, the same interference/noise was (barely) audible through the headphones as well! The microphones were probably picking it up! I have no clue why this damn signal is so powerful and intrusive all of a sudden...

I spent the last 2 days essentially re-arranging my entire system. I THINK (I hope I am not shooting myself in the foot here) I found a place where the turntable is directly connected to the McIntosh's MM phono stage and does not pick-up the interference. Once I placed the table in a different spot (about 2 meters from its previous location, away from the only window in the room), and connected it straight to the MM input (only 1 cable run, no external phono pre-amp), the noise in the McIntosh was gone, and so was the FM/RFI interference.  

Still experimenting, however. I hate the new location I was forced to use for the turntable, but I suppose I will need to live with it, since the alternative would be worse.