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.