From this post on the Manjaro forums, I installed the realtime-privileges package and added my user to the group.
Install
realtime-privilegesand add your user torealtimegroup, then reboot.
That removed the RealTime message window at the start, but the crackling sound was still there with any sounds.
I’ll look into your PipeWire configs, but this does look complicated. We’re all here to learn tho.
Does it get better when you install this: GitHub - vagnum08/cpupower-gui: cpupower-gui is a graphical program that is used to change the scaling frequency limits of the cpu, similar to cpupower.
and have your CPU running in performance mode?
I thought Pipewire was introduced to make things easier … 
[click-clack …a few moments later…]
No, and I think that is because punching the gas won’t help with a clogged carburetor. It might be a RealTime kernel issue.
That’s an awesome GUI tool tho! #themoreyouknow
Also possible. Just install the non realtime kernel to check. It’s usually not needed and the stock is more stable.
I’m not using the RealTime kernel. So, could that be the issue?..
We need to use RealTime kernels now for a modern DAW to work?
No, nowadays you don’t need realtime kernels. Maybe that’s needed when you record a lot of live instruments with super low latencies, but not for electronic music with Renoise.
Yeah, I just downgraded to linux66-rt and it hasn’t helped. So, we know it is something in the sound stack with Manjaro. I think it is a distro issue that will probably get solved with time.
What audio interface do you have and did you make a test with the internal sound card?
Manjaro is natively using PipeWire and the jack2 package. I installed it with a yay installer for renoiseAUR. That repository may explain more about the audio interface.
I don’t know how to make an audio test on the sound card. But, everything else always works… F£ $tud!0 (don’t tell), Spotify, Renoise on Windows (same machine), even Disney+ through Edge on Linux! Nothing makes this crackling sound anywhere, only Renoise on Linux kernel 6 (6.9 and 6.6RT).
Using Renoise in Linux worked fine at first, installed Pipewire and everything was working fine. Then I discovered that all the audio was only coming out the left channel, everything’s mixed right and annoyingly when I unplug the audio interface or headphones the left and right channels both play on the laptop speaker. In the course of trying to fix it I instead broke all the audio and only got it working after some effort, but now whenever I open Renoise it belches out this awful extremely loud static.
Good luck to you, but I’m probably just going to use a computer running windows for musical activities, because trying to troubleshoot Linux just drives me crazy.
Which Distro are you on?
Mine is Linux Mint
Maybe you can check if the Ubuntu studio installer is available and install this. I could imagine that it will fix your issues:
Use Pipewire and Pipewire-Jack with Renoise. It should work well on Renoise using JACK as the audio system on Linux. Depending on your interface and your preferences, you can set the sample rate and buffer size in your conifg files for both Pipewire and Pipewire-Jack respectively. Just note that if you want a high sample rate, you would want the Pipewire config file to have the same high sample rate as you set up on Pipewire-Jack otherwise you would have this problem where the audio on Renoise sounds garbled, slowed down mess. Your config files are located on /usr/share/pipewire but you should copy and paste the pipewire.conf file and the jack.conf file from there to either /etc/pipewire/ or ~/.config/pipewire. The latter location is within your home directory which may be more convientient because you wouldn’t need root permissions to edit and configure that way. Then you can edit your config files that way.
Also a rule of thumb on audio production on Linux, there is this tool called “rtcqs” which is a Python script that tells you what you would need to do to optimize your Linux system for audio production. You can find it here. I would do everything it says except the “Spectre/Meltdown Mitigations” part especially if your CPU is made by Intel. If you’re setting up an “audio workstation” where the only thing you do on that system is audio production and it isn’t your personal computer for everything else, you can disable those mitigations for better performance.
Did you try to switch your setting in the pulseaudiovolume control under configuration from ProAudio to your interface name and back when this crackling occurs. Is it a crackling or a stuttering what you hear?