P1 Mini hum

Audio Gear Talk Lumin
1

Hello everybody, let me introduce myself since it is my first post here. I am Xavier from France and I am a Roon subscriber since September 2020. But more importantly for this group, I own a Lumin P1 Mini since April 2025, which I chose after some serious thinking/comparing on the subject of streamers/DACs.

I have been pretty happy so far with the simple system I built, PMC 2 way speakers for a small to medium room with a Moonriver amp and finally the P1 Mini as a source (next step envisaged being some acoustic treatment). However, a few days ago, the Lumin stopped being dead silent, as you would expect from such a device. I started hearing a low pitched hum clearly coming from the P1.

That hum is not obviously audible when the music is played, except between tracks or when the music is heard at low volumes, but easily audible 3 meters away from the device otherwise. How do I know it is the P1 and not something else? The hum is there when both the amp and the internet box are turned off. Not connected to the amp or anything else? I have tried that too, and in a different room, in case that would have had something to do with the power socket and circuit, with the same result.

-The hum comes and goes cyclically. It lasts about 30 seconds, followed by about 45 seconds of relative silence (if I put my ear on it, it’s not really silent then but that might have been normal and might have been the case since the beginning, I haven’t tried before) and starts again.

-The pattern remains the same whether the P1 plays music or not (I have tried “playing music” with the amp off to be able to clearly hear the hum if it would still be there).

-When the amp is on and some music is actually heard through the speakers, the noise does not seem to affect the audio signal.

-It makes no difference whether the P1 is in stand by or not.

Nothing has changed in the system between when it was making no audible noise at all and now. No cable deplugging or anything, so I am somewhat worried. The only difference is that I let it rest turned off for about 10 days before the hum appeared, whereas before I was using it every couple of days or so.

Any idea or tip any experience user would have?

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Maybe this post/thread can help you understand what is happening?

3 Likes
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Thank you for pointing this out to me. This is very likely to be the correct hypothesis here, for I have discovered that a cyclical hum is also coming from the amp (toroidal transformer inside as well), which was also dead silent before. I had not noticed when I first posted because the noise coming from the P1 mini is more audible and because I was always turning on the latter before the amp.

So for now ì am going to give a DC blocker a try. Is anyone familiar with that device? https://www.tagaharmony.com/en/products/3661/conditioners-and-filters/product/9158/dc-100-dc-blocker Any red flag associated with it?
Here in France, the iFI DC blockers are also easy to get but contrary to this one, you need one per audio component. The Taga supposedly can take care of both and more (I am considering getting a third component in the rack, the Lumin L2 being envisaged as the size of my library is growing).

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I previously the iFI DC Blockers to great effect and they had no detrimental effect on the SQ.

May not help directly with your proposal, but does confirm that these items do actually work.

DG…

1 Like
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Follow up: I received the aforementioned Taga product. Initially I thought it made no difference because the hum was immediately audible when turning on the P1 Mini. However, it does. The less loud hum from my amp is not audible anymore and the noise coming from the P1 Mini is significantly less loud. In fact the cycle seems to be altered and without music one can hear the hum lasting a few seconds instead of 30. Another thing is that after some time functioning, the noise becomes even less audible, as if the P1 getting warmer somehow helped. Perhaps someone knowledgeable about electricity and transformers would tell us this is to be expected.

In any case, I conclude that the suspicion that the cause is DC offset seems warranted. And that the DC blocker from Taga mitigates the issue.