JACK capturing onboard mic
Posted: Fri Jan 11, 2019 4:39 pm
I'm using a new Ubuntu 18.04 install with kxstudio on an Acer Aspire V laptop. Running the quickscan script gives:
lspci gives (edited):
Cadence -> Configure -> Driver -> Input Device is set to "none", and Output Device to "hw:PCH,0 [ALC283 Analog]".
With JACK running (no MIDI or PulseAudio started), I open Catia and Guitarix, and add (for instance) the multiband distortion module to Guitarix. However, once I connect the system capture to gx_head_amp, I get a whining noise,and if I (eg) shout I can hear that on the Guitarix-modulated output!
This suggests that capture is linked to the onboard mic in the laptop, but I can't find any way to turn that off. I've used alsamixer to select the HDA Intel PCH entry and mute Mic Boost and Capture, but it has no effect.
I was originally trying to use a Scarlett 2i2 USB input (selecting it as the Input Device), and trying to trace the godawful whine from that led me to the above minimal configuration. The odd thing is that I tried the 2i2 a couple of days ago, and I can't remember the whine being there then. In the meantime I installed a couple to WINE apps to test them (Guitar Pro and Reaper) - could that have anything to do with it?
Any advice on how I can fix this problem would be gratefully received.
Code: Select all
== GUI-enabled checks ==
Checking if you are root... no - good
Checking filesystem 'noatime' parameter... 4.15.0 kernel - good
(relatime is default since 2.6.30)
Checking CPU Governors... CPU 0: 'powersave' CPU 1: 'powersave' CPU 2: 'powersave' CPU 3: 'powersave' - not good
Set CPU Governors to 'performance' with 'cpupower frequency-set -g performance' or 'cpufreq-set -c <cpunr> -g performance' (Debian/Ubuntu)
See also: http://linuxmusicians.com/viewtopic.php?f=27&t=844
Checking swappiness... 10 - good
Checking for resource-intensive background processes... none found - good
Checking checking sysctl inotify max_user_watches... < 524288 - not good
increase max_user_watches by adding 'fs.inotify.max_user_watches = 524288' to /etc/sysctl.conf and rebooting
For more information, see http://wiki.linuxaudio.org/wiki/system_configuration#sysctlconf
Checking access to the high precision event timer... readable - good
Checking access to the real-time clock... readable - good
Checking whether you're in the 'audio' group... yes - good
Checking for multiple 'audio' groups... no - good
Checking the ability to prioritize processes with chrt... yes - good
Checking kernel support for high resolution timers... found - good
Kernel with Real-Time Preemption... not found - not good
Kernel without real-time capabilities found
For more information, see http://wiki.linuxaudio.org/wiki/system_configuration#installing_a_real-time_kernel
Checking if kernel system timer is high-resolution... found - good
Checking kernel support for tickless timer... found - good
== Other checks ==
Checking filesystem types... ok.
** Set $SOUND_CARD_IRQ to the IRQ of your soundcard to enable more checks.
Find your sound card's IRQ by looking at '/proc/interrupts' and lspci.
Code: Select all
00:03.0 Audio device: Intel Corporation Haswell-ULT HD Audio Controller (rev 09)
00:1b.0 Audio device: Intel Corporation 8 Series HD Audio Controller (rev 04)
With JACK running (no MIDI or PulseAudio started), I open Catia and Guitarix, and add (for instance) the multiband distortion module to Guitarix. However, once I connect the system capture to gx_head_amp, I get a whining noise,and if I (eg) shout I can hear that on the Guitarix-modulated output!
This suggests that capture is linked to the onboard mic in the laptop, but I can't find any way to turn that off. I've used alsamixer to select the HDA Intel PCH entry and mute Mic Boost and Capture, but it has no effect.
I was originally trying to use a Scarlett 2i2 USB input (selecting it as the Input Device), and trying to trace the godawful whine from that led me to the above minimal configuration. The odd thing is that I tried the 2i2 a couple of days ago, and I can't remember the whine being there then. In the meantime I installed a couple to WINE apps to test them (Guitar Pro and Reaper) - could that have anything to do with it?
Any advice on how I can fix this problem would be gratefully received.