Norns Shield Noise

I am concerned about background noise from the output of my Norns Shield. I recorded a noise sample (I amplified it by 6 db to make it more noticeable). In addition to static noise, there is a certain pulse that sounds at the time when the red LED on the Norns flashes. Is this normal or not? This noise is not very noticeable when I use synth engines, but when I record something (using for example Cheat Codes or oooooo), norns becomes almost unusable to me because I make quite minimalistic music and all these noises after mastering become very noticeable (their level at the input of my sound card is about -40db).

Noise Sample: Dropbox - Norns Shield Noise.wav - Simplify your life

2 Likes

hi Denis! hope all’s well :slight_smile:

this has come up a bit recently – shield is more susceptible to noise (incl. bleed from digital clocks on the board), but the presence is largely dependent on your power supply + power cable and gain staging.

monome highly recommends this power supply. the Pi3B has a micro-USB power port and requires at least 2A and 5.25V ideally supplied through a cable with 24AWG or less. lower AWG = lower noise & more stable voltage delivery for better performance. most consumer USB cables do not meet this spec, so please be sure to keep an eye out . you can also use a portable USB battery if it’s sufficiently large.

hopefully this helps! feel free to email help@monome.org if you feel the unit needs technical support :revolving_hearts:

6 Likes

To complete, in good conditions, the noise floor on norns shield is at most -96dB.

See here for a measurement.

So it could a charger issue, or improper gain staging (preamp gain after norns instead of before).

Mastering generally involves a fair amount of upward compression, that indeed cause quiet sounds to be more loud.

Using a gate + selective filtering on your tracks coming from norns should help you remove a good amount of noise (at least during the quiet parts). More advanced cleaning could be achieved with stuff like Izotope Rx.

2 Likes

dope, thanks for closing the gaps on the additional info!

this +10000 – i just downloaded the demo the other day and was blown away by how powerful it is.

1 Like

Thank you for your answers. Initially I used the original power supply from Pi3B but then I did some comparative tests and settled on a power supply from my xiaomi phone (model of power supply is MDY-10-EF, with 5V-3A). Oddly enough, but in my tests it gives less noise, but I have not yet experimented with different cables, and apparently this is the next thing I will do.

As for gainstaging, I haven’t fully figured out the levels section in norns yet. Would you recommend leaving the controls on by default, or would it make sense to set output level to the maximum so that the soundcard receives a higher level and does not have to do extra amplification?

it’s possible to over-gain noise in the new norns software. “unity” is indicated with a dash at 0.0db. any higher and you’ll be amplifying noise.

3 Likes

hmm, it seems to make sense, I began to pay more attention to this noise after the recent software update. So, what can I do to avoid this over-gain noise? In which menu can I configure this?

To complete.

The trick is to have the best SNR (signal to noise ratio).
So ideally use a preamp (such as a mixer channel strip) before norns input to have a signal high enough.

Don’t overdo it, or you’ll clip the input (resulting in distortion).

Regarding norns’ internal mixer:

  • do not boost the output (or you’d boost noise, as @tehn pointed out)
  • do boost the input but only if you have no preamp before the input. It’s not ideal but should result in less noise than boosting the output.

If you recorded at the appropriate input level, norns’ output should be loud enough to not need any preamp gain when going into your sound card.

1 Like

the mixer page of the main menu, just scroll left past the tape page :smiley:

This completely duplicates the “levels” page in edit menu? Also I don’t really understand the difference between the “monitor” and “output” sliders, it seems they do the same thing on the shield, right?

“monitor level” is for passing incoming audio (unprocessed) to the output.
Output level is the processed signla.

Having trouble finding this exact power supply in the UK. Would something like the below work(sorry for the Amazon link) ? I have a 3a 5v supply at the moment but getting a lot of crazy crackles and stuff especially when I have a Grid plugged in to my Shield, so I want to get something 5.25v to hopefully put an end to that.

Cheers!

Edit - I bought this power supply and I thought my issue was gone but it’s still happening. I’ve attached a video if anyone has encountered the same issue ?

I have an official pi power supply arriving tomorrow. But this one above is 5.25v at 3a so surely this should still be causing an issue.

This issue seems to happen out of nowhere, could be 5 minutes in to using Norns or 3 hours. Once it happens no matter how many times I reboot the issue remains until I leave the Norns for hours (normally I just come back to it the next day)

Any ideas on this ?

I’ve also had significant noise issues with my norns shield. Doesn’t seem to matter what script I’m running or if it’s recorded external audio or internally generated audio. My power supply seems to have basically the same specs as the one mentioned. I am well aware of the gain staging and by default have the input boosted but this doesn’t help with audio generated internally. I always have to use izotope rx but even that doesn’t eliminate the issue, just lessens. I thought it was just the rasp pi but it sounds like this issue isn’t universal with the shields. Any ideas on things to try??

1 Like

Expect more noise from the (low-cost, low-parts) shield and pi, vs factory. People have different tolerances for what is acceptable, so it helps to be precise. Expect -96db steady state floor and transients up to maybe -84db from clock bleed. (This is in the pi header, hard to work around; not using screen or wifi will mitigate.) Comparee to -120dv floor on factory.

If you suspect something worse we could use a measurement, or a good recording showing full dynamic range.

or too, some description could help:

  • 60hz harmonic hum? (soldering preblems?)
  • something that modulates with screen or network activity? (kinda expected)
  • steady state hiss? (idk)
  • some other weird crud?
1 Like

How does one turn the screen off?

I understand its lower cost, but no other device I’ve spent £100’s on has a noise issue like this. Tho I also understand how to make such a noise level ‘useful’ in its own right, I’m definitely looking to ‘upgrade’ to the real Norns as I love this device and its ecosystem and uses.

I love Barcodes atm, but the noise is definitely worse with a screen full of activity.

Seeing as I’m at home most of time, is there a way to use my spare HDMI monitor instead of the onboard screen? Would that help?

Could also be an electrical problem(s) in your house/room.
The (factory) Norns shield of my GF was outputting crazy noises when she tried to use it in a specific room in her school, she kinda freaked out about this but plugging it elsewhere solved the troubles immediately and it was back to normal.

1 Like

you can write scripts that don’t use the screen. sorry but many of my answers are going to be sort of like that.

yeah it’s possible to use HDMI, use other audio devices (as you’ve seen) and so on. “possible” by hacking it, not in a super deep/complicated way.

i’m responsible for a lot of the more functional layers of the norns stack (softcut and so on); as time permits we can bit by bit also work on more transparently supporting other hardware, but is mostly gonna rely on contributions. using an external screen is a pretty low-hanging goal that is actually not far from landing pending some merge work. selecting other audio devices also basically not a big deal. but at that point the norns stack is basically independent of hardware and you can just run it on whatever linux computer.

sorry you’re not happy with the cost/noise ratio. not really my department, i’m just telling you the numbers i’ve seen, which are not hifi professional but also IMHO acceptable for what it is. (i’ve had worse digital-bus-noise problems with much fancier devices, and my “basic prosumer performance” computer+interface setup is maybe $2.5k street value, so IDK. )

but i still have no idea if the noise you are seeing is at all like the noise i’m expecting, without recordings or measurements or something… can you make some kind of estimate of the actual noise floor you are seeing so that people here can discuss your issue more effectively? like is it worse than -80dB? if it is, there could be some issue besides the design limitations.

in any case, apologies, i think i should get out of here now and go back to focusing on SW improvements where the value of my effort is less ambiguous

just wanna clarify that when i say “factory norns” i mean the steel box with the custom PCB running on the compute module, not a shield running on standard raspi.

1 Like

Dont get me wrong, its not that I’m not happy per se, its more trying to get a handle on what I can do, whats possible to deal with it. Just getting my head around it still, and using Norns Shield on its own instead of in a mix which makes things more noticeable :slight_smile:

Im certainly happy enough to want to pay for a factory Norns :slight_smile:

And my own apologies for banging on about it so much :slight_smile: I shall do as you say at some point and upload a recording to see if I have some other issue making this worse or if I’m just focusing on it too much. I’m autistic and have OCD and lots of wonderful stuff so I get a bit obsessed drilling down into things sometimes! Still, if I what I’m hearing is standard, it seems like an issue that might need a work around the more popular Norns Shield gets, as it looks like I’m not alone with finding the noise a bit distracting for quiet ambient work.

Thanks for the reply, I appreciate it! Sorry for being ‘that guy’ :slight_smile:

@sns Yeah, thats def occurred to me too. Another aspect I need to properly investigate. Tho using a battery pack helped none, I havent tried outside or every room in the house.

Tho if one of those is a solution, that then does then limit my use of the Shield quite considerably and is not an issue I have with the rest of my gear. Still, limitations can breed creativity.

no no no worries, i get it.

yeah if you get a chance i’m curious to see your numbers. agree we should limit expectations. i’m also big into using hardware that i already have, and i like the norns stack, so at some point i want to just be able to run it without special hardware. but as you say, the shield HW appears to be popular and so it’s good to set expectations.

FWIW i’ve also done stuff with the pisound/patchbox, which is comparable to the norns shield but has pretty different design and different gain / noise issues:

  • it has preamp stage, which is fat and pretty clean (maaaybe higher hiss floor, but not unpleasing) but actually makes it impossible to deal with hot line level inputs without overdrive on input
  • it has similar noise from WIFI/BT action so i have to mess around and disable lots of things in the OS
  • it doesn’t have noise from the screen because it doesn’t have a screen
1 Like

Its kinda annoying with using the compressor, as I love the compression sound the Shield gets with everything interacting, but then it also amplifies this background noise. Embracing that and shoving a distortion pedal on the whole thing should mask all of that :slight_smile: Just slightly disappointing when I see all thse lovely quiet ambient pieces on youtube using Norns :slight_smile:

I shall look at the pisound/patchbox thing. This is all quite new to me, and this is my first experience of Pi’s even.

If the screen noise is a fairly common issue, I guess I should look into how to code turning it off and turning on the HDMI port on :slight_smile:

I havent coded a damn thing since 1987 in Basic on an Amstrad CPC464. And that was probably just getting the screen to flash ‘Max is a twat’ :slight_smile:

2 Likes