Volume knob doesn't adjust headphone jack output

Moderator: flatmax

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paisleyboxers
Posts: 2
Joined: Sat Aug 05, 2017 8:46 am

Volume knob doesn't adjust headphone jack output

Post by paisleyboxers » Sat Aug 05, 2017 12:02 pm

Should it be?

I can adjust with alsamixer, but not with the knobs.

```
$ cat /proc/asound/cards
0 [audioinjectorpi]: audioinjector-p - audioinjector-pi-soundcard
audioinjector-pi-soundcard

$ uname -a
Linux work-machine 4.9.40-v7+ #1022 SMP Sun Jul 30 11:16:10 BST 2017 armv7l GNU/Linux

$ cat /etc/*issue*
Raspbian GNU/Linux 8
Raspberry Pi reference 2017-03-02
Generated using pi-gen, https://github.com/RPi-Distro/pi-gen, f563e32202fad7180c9058dc3ad70bfb7c09f0fb, stage2
```

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

Re: Volume knob doesn't adjust headphone jack output

Post by flatmax » Wed Aug 09, 2017 10:01 am

Hi there,

Yes, the volume knob adjusts the RCA lines. You can control the headphone levels using the Master control in alsamixer.
If you want hardware control you could setup two buttons on GPIO lines for headphone vol up and down. The idea would be to detect a button press on the GPIO line and execute a script which sets the Master volume, perhaps using the amixer command. For example to set the Master level to 0 dB, you can do that from the command line like so :

Code: Select all

amixer sset Master 0dB
Do you think this solution would work for you ?

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

paisleyboxers
Posts: 2
Joined: Sat Aug 05, 2017 8:46 am

Re: Volume knob doesn't adjust headphone jack output

Post by paisleyboxers » Wed Aug 16, 2017 5:15 am

Thanks for sharing! After I found a cable from monoprice I was able to test with a pair of headphones on the RCA output.

I suppose next up is poking around for a Fancy knob I could attach to GPIO pins unless someone else has a link to a favorite one.

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

Re: Volume knob doesn't adjust headphone jack output

Post by flatmax » Wed Aug 16, 2017 10:00 am

Please let us know if you find one.

thanks
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

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