Alsamixer Volume - Distortion

Optimize your system for ultimate performance.

Moderators: MattKingUSA, khz

Post Reply
User avatar
lilith
Established Member
Posts: 1698
Joined: Fri May 27, 2016 11:41 pm
Location: bLACK fOREST
Has thanked: 117 times
Been thanked: 57 times
Contact:

Alsamixer Volume - Distortion

Post by lilith »

Hi,

I have a Behringer UMC204HD interface and have set the volume in Alsamixer for the interface to 100% (=0 dB).

However when using this sine wave generator

https://www.szynalski.com/tone-generator/

set at full volume I get harmonic distortion. When I set the volume in Alsamixer to 93% everything is fine and I get clean sine tones. Can anybody reproduce this and what is typically the best volume to set in Alsamixer?
Kott
Established Member
Posts: 818
Joined: Thu Mar 21, 2013 12:55 am
Location: Vladivostok
Has thanked: 65 times
Been thanked: 122 times

Re: Alsamixer Volume - Distortion

Post by Kott »

Hi,

Is your browser not using pulseaudio?
User avatar
sunrat
Established Member
Posts: 915
Joined: Wed Jul 22, 2020 2:08 pm
Has thanked: 151 times
Been thanked: 242 times

Re: Alsamixer Volume - Distortion

Post by sunrat »

PulseAudio uses ALSA under the hood. I always set volume at 93% in Alsamixer but distortion will also be affected by the level of the source. For some sources 100% will be fine.
That tone generator has a volume level slider, what is that set at? At what frequency do you get distortion? What level is set in pavucontrol?
User avatar
lilith
Established Member
Posts: 1698
Joined: Fri May 27, 2016 11:41 pm
Location: bLACK fOREST
Has thanked: 117 times
Been thanked: 57 times
Contact:

Re: Alsamixer Volume - Distortion

Post by lilith »

Volumes in Pulse are all set to 100%. It is possible that I changed the default alsa volumes and IIRC they are set below 100% by default. So this might explain it. I thought 100% equals 0dB and it should be fine but obviously this is not always the case. Volume slider on the tone generator page was also set to full volume (which gives a reading of 0dB on the pulse out channel).
User avatar
sunrat
Established Member
Posts: 915
Joined: Wed Jul 22, 2020 2:08 pm
Has thanked: 151 times
Been thanked: 242 times

Re: Alsamixer Volume - Distortion

Post by sunrat »

A pure sine wave at 0dB is a pretty hot signal. Do you hear distortion playing music?
Also the "sine wave" from that generator does not seem to be that pure; I noticed harmonics at certain very high or very low frequencies during a quick listen, so other artifacts may be present also.
User avatar
lilith
Established Member
Posts: 1698
Joined: Fri May 27, 2016 11:41 pm
Location: bLACK fOREST
Has thanked: 117 times
Been thanked: 57 times
Contact:

Re: Alsamixer Volume - Distortion

Post by lilith »

With music it's not obvious. The sine tones should be clean, at least I don't see any distortions with a spectrum analyzer.
Kott
Established Member
Posts: 818
Joined: Thu Mar 21, 2013 12:55 am
Location: Vladivostok
Has thanked: 65 times
Been thanked: 122 times

Re: Alsamixer Volume - Distortion

Post by Kott »

afaik pulseaudio has an option to do extra gain over 100%
Post Reply