[UNCONFIRMED] Distortion above 7000 hz.

Support questions for Neutron Player only.
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cggorman
Posts: 13
Joined: Mon Oct 07, 2013 7:12 pm

[UNCONFIRMED] Distortion above 7000 hz.

Post by cggorman » Tue Nov 26, 2013 3:14 am

See attached picture. Im not sure what type of distortion this is, but I wanted to report it. Hoping there is a fix.

The source file is a basic sine wave sweep. I replicated the results with five different sample rates from 44 to 192 and two different file types: wav and mp3. I also tried the same files in PowerAmp Pro. PowerAmp does NOT exhibit this distortion. I also tried toggling or adjusting every setting available. Nothing seems to affect it.

It is audible distortion that grows in intensity from about 7000 hertz.

I am trying to find driver\room resonance and eq them out, but the distortion above 7000 makes it virtually impossible.
Screenshot_2013-11-25-16-32-47.png
Screenshot_2013-11-25-16-32-47.png (166.56 KiB) Viewed 8155 times

dmitrykos
Site Admin
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Re: Distortion above 7000 hz.

Post by dmitrykos » Tue Dec 03, 2013 11:04 am

If you could attach the source music file it would be easier to comment. Without testing on device it is difficult to say anything.

I generated 7 kHz sine (with Audacy, 48 kHz frame rate of the file, 32 bit float WAV format, test device has 44,1 kHz frame rate) and played the file in Neutron. The spectrum looks fine: with/without - EQ, Dithering. So the frequency error must be coming from your file source may be.
sine 7khz 48khz.png
sine 7khz 48khz.png (25.18 KiB) Viewed 8135 times

cggorman
Posts: 13
Joined: Mon Oct 07, 2013 7:12 pm

Re: Distortion above 7000 hz.

Post by cggorman » Tue Dec 03, 2013 6:37 pm

See attached. Around 7k seems to be the cutoff. Above that (7500k+), it gets worse as the frequency increases. In the specturm display, you can watch the comb crawl to right and eventually double back like a wave hitting a wall.
Attachments
Screenshot_2013-12-03-13-07-16.png
Screenshot_2013-12-03-13-07-16.png (175.72 KiB) Viewed 8131 times

cggorman
Posts: 13
Joined: Mon Oct 07, 2013 7:12 pm

Re: Distortion above 7000 hz.

Post by cggorman » Tue Dec 03, 2013 6:43 pm

Can't seem to attach .mp3 or .wav files.

Check here: http://www.audiocheck.net/testtones_sinesweep20-20k.php

I know I was using a couple of those. There were others I tried as well, but I can't remember where I got them and a quick search isn't turning up anything familiar.

dmitrykos
Site Admin
Posts: 1914
Joined: Mon Apr 25, 2011 6:15 pm

Re: Distortion above 7000 hz.

Post by dmitrykos » Fri Dec 06, 2013 1:35 pm

Ok, thank you for the links. I downloaded this file from your link:

http://www.audiocheck.net/download.php? ... 20klin.wav

Then played it with Neutron using 32/64 bit mode, with EQ on/off, Surround on/off, with/without Dithering, ARM and x86 CPU and can not confirm your behavior. E.g. The sweep frequency is moving all the way without any additional frequencies. I noticed no problems on my devices.

Please try the WAV file which I provided. What will be your results?

cggorman
Posts: 13
Joined: Mon Oct 07, 2013 7:12 pm

Re: Distortion above 7000 hz.

Post by cggorman » Fri Dec 06, 2013 2:51 pm

Just like the log progression except the distortion starts higher, like 9500k.
Attachments
Screenshot_2013-12-06-09-46-58.png
Screenshot_2013-12-06-09-46-58.png (95.19 KiB) Viewed 8115 times

cggorman
Posts: 13
Joined: Mon Oct 07, 2013 7:12 pm

Re: Distortion above 7000 hz.

Post by cggorman » Fri Dec 06, 2013 6:41 pm

The stock music player and PowerAmp don't have spectrum displays so I can't post a pic as proof, but neither of those have this audible distortion.

Device is Verizon LG G2, model VS980, stock ROM (aosp 4.2 based) and stock kernel. I may try AOKP 4.3 and a custom kernel this weekend to see if it helps this issue.

I know LG wrote a lot of audio code to make android capable of high rez audio output. Maybe something not playing nice with the Neutron shell.

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