[LAU] Odd volume issue with jackd

Len Ovens len at ovenwerks.net
Mon Apr 23 20:31:07 CEST 2018

On Mon, 23 Apr 2018, Mark Raynsford wrote:

> Why are programs on my workstation so much quieter? They're actually
> quiet enough to be problematic on their own. It's evidently not a
> hardware issue, because I can get the hardware to play loud enough
> sound simply by producing audio on the second machine.
> Is there some sort of master volume level per-machine that I can look
> at? Any ideas what might be causing this?

While you are using jackd as you sound server, you do have PulseAudio 
bridged. If the Pulse ALSA module for that audio card is still active, 
pulse may not be able to connect and send audio to that card but it can 
still control levels on that card. This has hit me several times before I 
turned the profile (in pavucontrol) to "Off" for that card. If using 
Pavucontrol, look at the Configuration tab. If your audio device is 
listsed there use the drop down for it to turn it to off. I notice MATE 
has a different pulse utility and the tab there is called hardware instead 
but allows the same thing. In my case I use the following two lines before 
I start jackd:

pactl unload-module module-udev-detect
pactl unload-module module-alsa-card

The first line tells pulse not to monitor udev for newly plugged in USB 
audio cards, and the second removes any already detected audio cards. In 
my experience this makes for a very stable pulse front end/jack back end 
set up. Everything works including freerun mode in jack.

After turning the device off, use alsamixer to reset your levels. Pulse 
does interesting things with input levels on internal cards varying both 
input level and input boost (even when aux in and not mic are used) for a 
smooth level transition (noise floor on the other hand may bounce around 
all over the place depending on the analog components).

Check first that this doesn't solve your problem as turning the card off 
is a one click operation.

Len Ovens

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