Max amplitude is low

Moderator: flatmax

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moggyd
Posts: 22
Joined: Wed Jul 05, 2017 5:09 pm

Max amplitude is low

Post by moggyd » Sat Nov 04, 2017 3:13 am

Hi

Have been playing with this board again - have it all working fine but the aplitude of the recordings is low compared to my PC and another sound card I have for the pi.

e.g. with a line in source
ffmpeg -f alsa -i hw:0,0 -t 30 out.flac

creates the file fine, but when viewed in Audacity the max/min values are 0.5 and -0.5 rather than recordings from other cards which have max 1.0 and min -1.0.

Is there some amixer magic I need to do to fix this?

Thanks

flatmax
Posts: 609
Joined: Sat Jul 23, 2016 11:39 pm

Re: Max amplitude is low

Post by flatmax » Sat Nov 04, 2017 1:03 pm

If you can boost in alsamixer, that would be your best choice.
Alternatively, the Audioinjector Zero doesn't have 6 db limiters on input, it is another option.

Matt
Check out our audiophile quality crossovers : https://bit.ly/2kb1nzZ
Please review the Zero sound card on Amazon USA : https://www.amazon.com/dp/B075V1VNDD
---
Check out our new forum on github : https://github.com/Audio-Injector

moggyd
Posts: 22
Joined: Wed Jul 05, 2017 5:09 pm

Re: Max amplitude is low

Post by moggyd » Sun Nov 05, 2017 1:13 am

OK I can now record with full range. Got it working with a custom .asoundrc file listed below. This gives an extra slider labelled "inboost" in alsamixer. I set it to max and adjusted down using the hardware input control - that way it should be able to deal with lower input levels like turntables.

BTW I had to enable "ADC High Pass Filter" otherwise there was a massive DC offset. What does this setting do exactly?

pcm.!default {
type asym
capture.pcm
{
type plug
slave.pcm "softvol"
}
playback.pcm
{
type plug
slave.pcm "dmix"
}
}

pcm.softvol {
type softvol
slave.pcm "dsnoop"
control { name "inboost"; card 0; }
max_dB 16.0
}

ctl.!default {
type hw
card 0
}

jessecobra
Posts: 14
Joined: Tue Oct 31, 2017 3:53 pm

Re: Max amplitude is low

Post by jessecobra » Tue Nov 07, 2017 12:23 pm

flatmax wrote:
Sat Nov 04, 2017 1:03 pm
Alternatively, the Audioinjector Zero doesn't have 6 db limiters on input, it is another option.
Do you have this documented somewhere? ;)

flatmax
Posts: 609
Joined: Sat Jul 23, 2016 11:39 pm

Re: Max amplitude is low

Post by flatmax » Thu Nov 16, 2017 8:40 pm

Where do you think is a good place to document this ?

Matt
Check out our audiophile quality crossovers : https://bit.ly/2kb1nzZ
Please review the Zero sound card on Amazon USA : https://www.amazon.com/dp/B075V1VNDD
---
Check out our new forum on github : https://github.com/Audio-Injector

robiwan
Posts: 59
Joined: Wed Jul 05, 2017 1:18 am

Re: Max amplitude is low

Post by robiwan » Mon Nov 20, 2017 5:42 pm

flatmax wrote:
Sat Nov 04, 2017 1:03 pm
If you can boost in alsamixer, that would be your best choice.
Alternatively, the Audioinjector Zero doesn't have 6 db limiters on input, it is another option.

Matt
Matt, is there a way to tell whether it is a Zero or fullsize WM8731 card that is attached, to be able to apply the softvol boost only in the case of the latter ? Also, regarding the 6 dB limiter, is it possible to remove it ?

jessecobra
Posts: 14
Joined: Tue Oct 31, 2017 3:53 pm

Re: Max amplitude is low

Post by jessecobra » Tue Nov 21, 2017 6:25 am

flatmax wrote:
Thu Nov 16, 2017 8:40 pm
Where do you think is a good place to document this ?

Matt
On this forum of course!

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