Noise Floor from Nucleus Plus usb port

Roon Core Machine

Nucleus +, new

Networking Gear & Setup Details

Nucleus +, usb to sandisk pro portable ssd, usb 2.0 audioquest cable to Rotel 1590 mkII preamp, xlr out into Neve 1073 dpx line input —> into music studio audio chain. Also, ethernert connection to router with audioquest cable only for streaming. Speakers are Neumann kh310 monitors, KH 750 sub

Connected Audio Devices

Number of Tracks in Library

Description of Issue

There is a low level of two taps/clicks then a pause, like a clock sound when no audio is playing. Some noise is present with it.
It starts up after a song stops. I have identified it when turning up the gain of my Neve preamp. The noise/taps are only present when the usb is connected between the Nucleus + and the Rotel preamp. The sound disappears if either side of the usb cable are disconnected. Oddly, even if the Rotel preamp is powered down, the taps/clicks are still passed on if the usb cable is connected.
My workaround solution is that, luckily, the Rotel does not amplify the usb noise, so I use the Rotel for most of my gain and keep the gain of my studio equipment below the level that I hear the usb click noise.
However, I would like to use more of the gain in my analog studio equipment. What is this noise/click, and can I make it disappear? The only thing I have found so far is that it may be a harmonic of the digital clock from the Roon Nucleus +

There was been reports of coil whine with Nucleus before now but not clicks.

If your network cable is shielded, try unshielded and report back.

Thank you for a reply. I have disconnected the ethernet cable and powered off the router at the same time. Noise/clock taps still present.
I have sent an inquiry to Rotel technical support as to how this signal is even coming through the analog output of the Rotel pre amp even when it is powered off. The source must at least be the usb output of the Nucleus +, as the noise disappears when the usb cable is removed. I tried a cheap usb cable and there is no change.
Again, this noise is only present because I am able to amplify the signal coming out of the Rotel output xlr cables with studio amplifiers. I noticed yesterday, the noise is present during any silent parts of a song.
I figure this topic mostly pertains to anyone that may use the Nucleus + in a music studio environment. I haven’t tried other methods of sending the Nucleus usb output into my studio other than the Rotel pre amp.

Could there be some grounding issue between the Nucleus and the Rotel that allows the inevitable switching noise from a computer like the Nucleus to find its way into the Rotel because the grounds of the two devices are floating (or have high impedance at the relevant frequencies) relative to each other?

1 Like

Hello,
I received a response from Rotel tech support; they are referring the situation to their “team” to asses if the noise being transferred from the usb is spec or defect.
I agree with a potential ground issue, though the Rotel only has a two prong power with no ground.
The usb noise somehow is jumping onto the analog output before the primary signal hits the Rotel amplifier stage, since the noise isn’t amplified by the Rotel, but only amplified by my studio preamps and gain stages.
Which, overall, is my main goal, to use the gain stages of my mastering analog gear on any music file stored on the Nucleus + external drive.

Doesn’t that mean that the Rotel serves as a noise conductor (since its ground is floating) between the Nucleus and your studio gear? What I mean is, if there’s a variable signal between USB leads and ground leaving the Nucleus, it might pass happily through the Rotel (whose floating ground becomes just a signal path) and show up between analog and ground to your studio gear. Just thinking aloud here, but in general I’m skeptical of two-prong power for signal path audio gear such as DACs and preamps.

I’ll be interested to hear Rotel’s response. They may have had to dump the usb ground somewhere. If the chassis was grounded to the xlr output ground, then the noise wouldn’t be on the balanced lines, pin 2 or 3. The ground is pin 1.
On the other hand, if the usb is floating on the Rotel, then the signal could radiate onto a nearby balanced line, pin 2 or 3. The signal is very weak. I was amplifying the Rotel signal when it’s output was only 22 on the volume meter. I could set the Rotel for line level output, but then I can’t send that into my Yamaha amp/ Kilpsch setup on line 1. This setup provides 2 different paths for 2 different purposes.Output 1 is standard hifi, Output 2 is Neve preamp using the Rotel dac.
The analog studio equipment adds another level of control, and basically makes music sound awesome. The Rotel sounds great on it’s own, for easy listening. Next level is essentially remastering the final 2 channels L/R of my favorite songs.

Looking at your Rotel‘s manual, I see that there‘s a GND/earth lug connection screw at the back of the unit, on the opposite side of the AC inlet.

You may attach a wire to that and connect it to your AC outlet’s PE, or probably even better, to your Neve’s chassis, which, I presume, has a grounded chassis.

Then please report back about your findings…

1 Like
 I will try that when when I can.  I did place my hand on that lug while listening to the noise and there was no audible change.  Often, your body will add enough, capacitance I think, to act as a ground, at least partially enough to hear an audible change.  Like touching an old school radio antennae makes you part of the antenna and improves the audio.

Update. When wiggling the Nucleus + dc power plug, the noise signal would increase and decrease. This brought up the possibility that the Roon Nucleus + 19v dc switching power supply may be the noise source into the usb cable. Rotel feels this is a highly likely source.
Rotel also gave a list of like 12 things I can check.
I will also test running the Roon with a high quality linear power supply and see if the noise disappears.
This could be of interest in the general community in a situation where your Roon nucleus power supply is failing and the noise becomes worse.
Will report back, but may be several days.

Does Roon actually have technical support?
Update so far is that the noise does not appear to be from the power supply but something else related to the usb ground output.
I resolved the ground issue into my studio equipment by using a Radial Twin Iso, stereo xlr cable isolator, with the ground lift engaged.
I connected a laboratory grade Keysight dc power supply to the Roon Nucleus +. The taps/clicks repeating did not disappear. This is about the cleanest switching power supply available.
The Rotel uses some kind of floating ground where the xlr outputs are connected to all of the xlr output pins. Once a ground loop is formed, the usb noise is free flowing, but at a point after where the Rotel amplifies the balanced lines. The recommended ground isolators in the xlr path.
I would like to hear from a Roon technician if this usb noise is acceptable, or if I have a defective unit.
Anyone?

It’s very likely specifically to do with your system layout, so I doubt Roon will jump in to fix.

Better look into getting a proper USB isolator from companies like Intona.
Topping has something a little cheaper on offer.

I had problems with audible noise over USB through my DAC balanced analog out, generated by the power conversion board in my fanless Roon server PC.
Could only fix it with a Intona unit, case closed.

1 Like
 Thank you for the extra tips.  Yes, listening tonight, my system is sounding wonderful.  Whether it's the outboard Radial transformer w ground lift, a usb filter, or perhaps something worse stuffed inside of a Nucleus, a filter of some sort is required if the usb noise finds its way into your signal path.

When in doubt, one of these is a good starting point. I have a few Intona ones just in case.

Thank you. I ordered mine from Germany last night. I may prefer this route rather than an in-line xlr isolator. Tho I must say, the Radial Twin Iso is performing quite well. As this channel of my audio system is running into studio mastering components, I am basically altering the sound to taste.
Remastered cd’s of music from the 80’s, 90’s and early 2000 lend themselves well to adjusting eq, saturation and compression. Essentially, they have more usable data than the original mastered songs that were tailored more for radio broadcasts at the time. Sometimes, I think the sweet spot is somewhere between the two, depending on the song. It may be overkill, but, I am enjoying the music.

1 Like

Hi @corey_beggs,

Thank you for your post.

Please provide a timestamp or an example of a transition (two track names) so that our technical support team is able to identify an instance of your described phenomenon in diagnostic logging.

Please also clarify the following at your convenience:

  1. Does the file format of the local track affect this at all?

  2. Are you able to isolate this sound without any additional gain staging after the Rotel (by outputting directly to a speaker endpoint from the Rotel’s output)?

  3. How many wall outlets are in this setup, and where are they located relative to your equipment? We need to know contextually if the Nucleus, the Rotel, and any equipment afterward are on a separate circuit in your home.

  4. Do you have any DSP engaged within Roon when you encounter this?

  5. Lastly, are you able to record a video of this digital noise on a separate device, like an iPhone, so the team can hear what it sounds like?

Output to a studio setup is outside Roon’s intended use and, for broadcast piracy reasons, we don’t provide support to setups involving output to a mastering chain. Clearly, your case is innocent, and we want to address the Nucleus USB issue. That said, any troubleshooting will best involve a simpler chain without inputting to the Neve.

Thank you and we’ll await your response.

Thank you.

  1. Solved and resolved, tho not cheaply. USB noise from Roon transferred to Rotel. There are less expensive routes to ground isolation than I have chosen to test so far.

  2. I have an iphone video that clearly records the noise for your team. However, this portal will not allow me to drag and drop it or attach it here. Please forward your direct email and I will share it with you and your team. Signal route is Roon - usb - rotel rc 1590 mkII - xlr - Radial J pro iso - rca - yamaha A s1200 - Klipsch Heresy. This occurs while the 2nd xlr output of the Rotel is connected to an unpowered Neve pre amp, L and R channels of line input which is a true balanced input, with eventual true balanced stereo outputs of console.

  3. USB ground loop is formed between Nucleus+/Rotel and it’s two separate xlr channel outputs. The usb cable from the Roon connects its ground to the Rotel chassis, and there is continuity from Rotel chassis to all xlr output pins. Thus, when a ground loop forms, the usb noise passes down the main audio pathways. Of note, the Roon DC(-) power supply is connected to earth ground through the provided 19v switching power supply. This same earth ground is in continuity with the usb shield on the Nucleus + and then to the Rotel chassis.

  4. The noise in the video that I can provide; sounds like a repeating clock noise; completely disappears when either of 3 things happen that I have tested.
    4a. Disconnect the usb cable between the Roon and the Rotel.
    4b. Add xlr cable isolation with a ground lift on signal path to Neve.
    4c. Intona 7055 galvanic usb isolation between Roon and Rotel, which I tested today. Thanks to the community for this suggestion. It made me feel comfortable ordering the product from Germany.
    Except for 4a, I haven’t determined which one sounds the best yet…

  5. For the record, I do not re-record the songs I am running from the Roon into my studio. I do it for personal pleasure and entertainment. On any one day or night, my tastes may change so I just turn a few dials here and there, and make things sound better. I appreciate Roon for the simplicity and the Roon App interface. For me, this is the final process of going digital to analog. When music is recorded in studios, only the exact reversal of the process can bring one back to the original recording. Otherwise, we are all listening to something different. Having no idea what equipment was used to record all of the songs I have, all I can do is use what is available to me. I realize many people are purists to specific recordings of songs. All I can say is, there is an infinite scale that any one song could be adjusted along. Similar, but different. I am now, 100%, enjoying my Nucleus +

This topic was automatically closed 45 days after the last reply. New replies are no longer allowed.