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
@awn Tried everything. Different house circuits, "cheater" plugs, power conditioners -nothing helped! Sent the unit to Upscale Audio who said it tested "normal". I loved the sound and it had plenty of bass (!) but couldn't live with the hum. I believe that some shielding was accidentally omitted during assembly -that's my intuitional opinion. Damn shame, sounded great, couldn't use and I lost about $600 on the deal.

 If your  PrimaLuna is around 8 years old it is no longer under warranty. I would have a local tech take a look at it. If you don't know a good one, your dealer may have a suggestion. Since the hum is in both channels my guess is that the problem lies somewhere in the power supply.

 You may also want to take a look at the separates your dealer has.  A separate amp and preamp can have a higher level of performance than an integrated.


@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 :)