Purism Librem 13 v4 strange noises (?)

Software PureOS
1

Hi guys,

My purism librem 13 v4 computer seems to make a persistent subtle low level yet distracting noise. It is not connected to the internet, only the office apps are being used, and yet it emits a strange persistent noise, a bit like the tinniest fax machine in the world, a series of ongoing rapid tiny electrical squelch like sounds, a bit like buzzing but intermittent - if I press a key and hold the sound it is continuous, and then intermittent when released. It’s subtle, yet audible enough to be distracting. Anyone have the faintest idea what this is? Is it normal, common, or some clever way of being hacked? I can honestly say I’ve never heard anything quite like it. Let me know if this resonates with anyone or anyone has anything to say to this; I can also get a recording and upload it.

Any ideas? Does anyone else have this? I always thought laptops should be silent bar the fan when running hot. I can use the office software, but am concerned the security / privacy is somehow compromised despite hardware kill switches being on

Thanks, T

2

Can you record the sound and post it? Morbid curiosity on my part, I have no idea what this could be. I will say that I also have a L13v4, and have not noticed this.

3

Most likely ceramic capacitors, which are a bit piezzo-electric and generate acousting noise.
You may notice it that they play in sync with screen updates and key presses.

I hate it, but it is otherwise harmless.

2 Likes
4

I’ll make a recording and upload it. I don’t know what ceramic capacitors sound like or what causes it- whatever it is it’s audible enough to be distracting but faint enough to not be a big deal, except of course if it is some hack technique to extract data. Hope not! Let me know thoughts when I get around to recording / uploading it some time this week. Thanks!

5

you know this is one of those moments from the Next tv-series released in late q4-2020 where they try to ‘erase’ the A-g-i and notice a sudden spike in fan noise and heat output throughout the whole NSA black-site data-center … to-put-on or NOT-to-put-on my tin-foil-hat-ON ? …

all kidding aside. i tend to notice this ‘noise’ too with my L-Mini-v1 … especially since i’m always paying attention to the ‘system-monitor’ app.

from my point of view this weird noise is generated by the integrated GPU (iGPU) in the intel combo unit …

i don’t notice this sound coming from my workstation even though it should be audible since it draws A LOT more power than the tiny compute package inside the LMini.

it could be the GPU-VRM since it’s integrated and all … you might derive more inspiration from the channel - ActuallyHardcoreOverclocking from snooptube - it has much AV material covering hardware components and coil ripple, etc. worth a few hours of exploration IMO.

6

Maybe you should donate it to the Floppotron?

7

Does the sound change when you disconnect/connect the power to the notebook?

I had some similar issue and disconnected the internal right speaker of my notebook to verify that it has been that part that emitted the sound.

I left it disconnected, since I never use the internal speakers :wink: …

8

What you are talking is called a ground hum, and should not be a problem in a laptop, that it was is very strange.

9

Thanks for the hint. I’m not an electric engineer, but I’d say it can’t be that:

  • tested in two different locations (buildings) using two different power converters
  • each test repeated with plug turned by 180° (could be a missing grounding connection in german three wire setup)
  • frequency doesn’t fit to 50-60Hz, sound is good described by @twilkins
  • only way to change the sound I found was unplugging or plugging in of the power converter. In these cases the noise sometimes vanished for some time
  • ground hum - to my knowledge - derives from the amplifier and should be heard in both channels in a stereo setup with a stereo amplifier with one power converter?
  • noise definitely only on right channel (tested by disconnecting left and right speaker separately)
  • setting of output level doesn’t make any difference

It is really barely heard, but with no other noise in the room it distracted me again and again. For the same reason I stopped using my bluetooth amplifier: very low unsteady noise.

I’m now using speakers with a buildin usb soundcard connected by usb. Excellent :slight_smile: !! No noise from the notebooks right speaker, no noise from the speakers when unused, but switched on.

10

Its a feature, the L13 is has its own white noise generator!

11

white noise is something different, that’s just MSS using side channel to exfiltrate the data using capacitors as emitters for AFSK

12

It doesn’t matter how many sockets you used. Laptops are not normally grounded. The battery acts as isolation in that regard. But the issue you are talking about is prevalent with people who do audio creation, etc.

I’ve never had any additional noises come from my L13, and I doubt it was built and specced with that noise noted as an acceptable tolerance. Here where I live in Germany, a lot of my musical equipment trips the circuit breaker, and that is more because of influx current, but I had to sort this out myself a while ago.

I’m not sure that is your problem, but from what you describe it sounds to me like something is grounded on the inside slightly and is causing the hum manifested in your speakers.

13

Still it is neither in the “speakers”, but only on the right channel built-in speaker nor would I describe it as a hum.

If your theory would be correct, would it also apply to running on battery (without power converter connected)?

14

No on battery you should not have any ground based hum. So if that isn’t the case then I’m definitely not right.

It is weird though for sure. I’m glad you found a solution for yours!

15

I have coil whine on my Librem13 v4 too. It’s especially prevalent at certain times, like if I’m using the webcam at all. Open cheese and it gets pretty annoying.

EDIT: Maybe your issue is different, I don’t know, adding just in case. I believe mine is going back for a broken hinge again anyways.

16

i remember that this ‘low-noise’ wasn’t as distracting on PureOS-9-Amber as it is on 10-Byzantium …

maybe it has something to do with the latest updates in the MESA stack … we’ll see once Byzantium becomes the new ‘stable’ and hopefully it won’t be so audible on the v2 and L14.

17

No it doesn’t make a difference whether the power cable is in or not. The recording came out badly, will need a better mic.

Ok so it’s a normal transistor / capacitor thing (?)- I can live w that