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
@beyondarkness  I have exactly the same noise coming from Dialogue Premium Preamp when used with certain amps. For example , it's gone when used with Pass Labs xa30.5 and it's present when used with Hypex Ncore monoblocks or Marantz AV receiver (when watching movies using the preamp's HT bypass). The unit is only 1 year old.
@tonediary  Interesting! In my case, it only developed in the last few months. My new speakers are more sensitive than the pair I used to have, so that may be why I did not notice the noise before. I did call Upscale Audio, but their response was "no clue!"... Sigh... 

Could you elaborate on how the noise sounds like on your end?

I do not want to ship it back to Upscale because they are on the opposite coast, the unit weighs 70+ lbs., and I do not feel like spending hundreds on shipping + insurance. I have had my fair share of horror stories with UPS, etc. Also, have not had the greatest experience with Mr. Deal in the past... 

I may be taking it to a local tech to see if they can find anything wrong with it.
@beyondarkness 
It sounds like "interference" just as you have described.
I'd also describe it as an extremely high pitched whistle sound , around 14khz probably. You can hear it for 5-6 seconds constantly and goes away before coming back in 10 seconds or so. It's always in a loop like this but you can only hear it in silent passages or when nothing is playing at all or even when the volume knob is turned down all the way.
I could describe it better maybe if my native language was English :) 
tonediary, thank you. That is exactly the same type of noise I get. Your description was perfect. 

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!