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Poor audio quality (Sailfish X, Jolla 1)

asked 2017-10-12 22:34:45 +0300

NevilClavain gravatar image

Hi there,

I used to use my Jolla 1 as my main phone, and I loved it. The one thing that bugged me was the sound quality when using headphones (or the jack in general). The problem is that whenever there is sound produced there are also some failt artifacts. Almost distortion or noise. It sounds a bit like there is extremely overcompressed audio playing in the background, but the sound that is being played in the foreground sounds fine.

I assumed that this was the Jolla 1 and that it just had a subpar DA-converter chip, but I've been using my Xperia X for months now and it sounds great, but as soon as I put sailfish on it the artifacts are back.

As with Jolla 1 when playing at high volumes it's not really noticable, but when playing at low volumes, particularly speach, it is downright jarring! Using an adapter to rise the resistence of the earbuds helps, but now that I understand that it is NOT due to hardware I cannot help think that this should be fixed.

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I didn't notice it on Jolla 1 much, but on Xperia X it's pretty obvious. Low volume audio is pretty distorted, you notice it for instance when a song starts or ends. It's not so noticable in the middle of a piece of music. This must be a fixable bug, as I'm sure it's not the hardware. Perhaps chip power-saving or sampling errors?

wvh ( 2017-11-09 15:23:07 +0300 )edit

I am so glad this is not just me. The audio quality and noise is intolerable, and makes for the worst media experience of any phone I've used. Please fix.

Sethdove ( 2017-11-14 22:32:16 +0300 )edit

I just changed the jack input on my Xperia X and it did nothing to the digital noise, so there is work to be done by Jolla here.

NevilClavain ( 2017-11-15 00:25:23 +0300 )edit

I can confim these noisy artifacts on Sailfish X when playing music on low volume.

Jorg ( 2017-12-09 14:36:33 +0300 )edit

I have the same problem with my Xperia X. Some kind of annoying distortion at low volume.

Wienerschnitzel ( 2017-12-20 09:40:39 +0300 )edit

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answered 2019-03-19 01:36:49 +0300

vmatare gravatar image

updated 2019-03-19 04:50:46 +0300

I'm pretty sure these artifacts stem from a fully powered final amplifier stage that drives the headphone jack. This theory is confirmed by the fact that they are most noticeable with low-impedance headphones. In fact, when I use my heavy 80 Ohm studio headphones, they are practically gone, whereas with tiny in-ears it's almost impossible to listen to music.

The root of the problem is that somehow the volume control only scales the waveform in software, while the final amplifier is always at maximum volume. As a result, the artifacts are sometimes even louder than the audio material itself.

So high-impedance headphones can be used as a workaround since they simply require more power. I've also heard of impedance-increasing adaptors (essentially a resistor) that may help.

However the real fix would be if we somehow figured out how to reduce the power output of the final stage amplifier, or better: scale it with the PulseAudio volume like it's done in a correct setup.


Edit: Did some more research and I think the WCD9335 is the chip responsible: https://developer.qualcomm.com/qfile/35460/lm80-p2751-29_a.pdf.

Looked through sysfs but couldn't find any helpful knobs to fiddle with. From the block diagram there should be some way to control the HPH_R and HPH_L gain, which I suspect control the amplifier volume. However I'm not sure whether the Xperia X uses an external headphone amplifier instead. It would be helpful if someone could post a link to the source code of the actual Sony kernel used on the device.

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I very much agree with your point of view. Do you have a solution now?

xbt123ufo ( 2019-07-03 14:15:45 +0300 )edit
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Asked: 2017-10-12 22:34:45 +0300

Seen: 702 times

Last updated: Mar 19