Clara HD Kobo Clara HD "whining noise" in silent environment

[brettonwoods]

Hi folks,

I recently acquired a Kobo Clara HD, running it with the latest firmware 4.25.15875.

As mentioned in this post from early 2019 [1], I can confirm that there is an audible "whining noise" when in a silent environment.

After noticing this I had the device replaced once but it did not help.

Specifically, I can hear the noise when there is load (like a new page is rendered).

When using Koreader or Plato, however, the noise is constant. (I assume because these alternative readers have a higher base load on the processor?)

Any ideas how to fix this?

Maybe wrap the device with some "noise cancelling" material/casing? I guess that is not really feasible, is it?

Any other experiences, confirmations, observations, suggestions regarding this issue?

Thank you very much,

Bretton

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[1] https://www.mobileread.com/forums/sh...d.php?t=316822

[NiLuJe]

Originally Posted by brettonwoods

When using Koreader or Plato, however, the noise is constant. (I assume because these alternative readers have a higher base load on the processor?)

They should all have essentially a null load when idle. This is doubly true for Plato & KOReader.

Which makes that observation... weirder. Unless you happen to have something like Wi-Fi enabled, which may already be a factor in the first place.

As far as I'm concerned, like I've said before, I have to put the device (Forma) right next to my ear to spot something (and, even then, I can only pick up the tiny high-pitched screeches in one ear. And those only in the bottom third of the device), which makes this a non-issue.
And Wi-Fi definitely makes it worse. As does being plugged to a power source. In which case loads actually makes it *better*.
And I certainly can't spot any meaningful difference between Nickel/Plato/KO, although we both do put the screen in a different framebuffer mode, so, apples & oranges, who knows.

[brettonwoods]

Originally Posted by NiLuJe

They should all have essentially a null load when idle. This is doubly true for Plato & KOReader.

Is there a way I can debug/log the load for each reader (Nickel,KoReader,Plato)? Would be interesting to verify this.

In Plato there is a "system information" section where I can see the load which is not "null". In Koreader there is a "system statistics" plugin, which has a similar result. How about Nickel?

Originally Posted by NiLuJe

Which makes that observation... weirder. Unless you happen to have something like Wi-Fi enabled, which may already be a factor in the first place.

I have Wi-Fi disabled at all times.

Originally Posted by NiLuJe

As far as I'm concerned, like I've said before, I have to put the device (Forma) right next to my ear to spot something (and, even then, I can only pick up the tiny high-pitched screeches in one ear. And those only in the bottom third of the device), which makes this a non-issue.

The "Forma" is a different device, right?

As for my device, the "Clara HD", I can definitely hear the "whining noise" in reading distance (ca. 20-40cm) in a silent environment (e.g. in the bathtub ;-) ).

[DNSB]

Originally Posted by brettonwoods

As for my device, the "Clara HD", I can definitely hear the "whining noise" in reading distance (ca. 20-40cm) in a silent environment (e.g. in the bathtub ;-) ).

I don't think I would recommend the Clara HD for use in the bathtub. It has no water protection.

[NiLuJe]

Both the actual *nix load average and the CPU time over process lifetime average done by KOReader mean nothing really interesting.

You'll notice I said "when idle". Of course the average is not null, work has to be done sometime to display stuff .

Get a shell, look at htop, and you'll see that pretty much zilch happens when idle, no matter the software being used. Same with perf counters.

The Forma may be a different device, but it's built on a very similar board than the Clara.

The thing they do have in common is that the screen is driven by a TFT. That those can whine in certain conditions is not new. I've seen it happen on laptops, and on desktop monitors as well, especially when displaying certain patterns.

[brettonwoods]

Originally Posted by DNSB

I don't think I would recommend the Clara HD for use in the bathtub. It has no water protection.

Ehmm... sorry, an empty bathtub of course. Yes, I'm reading in an empty bathtub. ;-)

[brettonwoods]

Originally Posted by NiLuJe

Get a shell, look at htop, and you'll see that pretty much zilch happens when idle, no matter the software being used. Same with perf counters.

I haven't used a shell yet with Clara HD. How do I get it?

As I understand there is a ssh server integrated with KoReader.

How about Nickel and Plato?

Cheers

[NiLuJe]

Here goes.

I was going to say the only not utterly outlandish conditions I could see this actually being heard while reading (as opposed to wearing the device like a pair of headphones) would be a tiny to small room with a potential for echo. And extremely good hearing, or someone suffering from tinnitus. I was thinking of reading on the toilet, but, sure, an empty bathtub could certainly fit the bill.