Since we’ve jumped to the Linux 4.19 kernel, which was necessary to be prepared for the Pi 4, we’ve been having troubles with clicks and pops on USB DAC’s (or more specifically: on some USB DAC’s).
The design of the Pi, with it’s shared USB/ethernet bus, makes USB transport very critical and something got broken in the 4.19 kernel. This has been known for quite a while, but still no fix is found yet. Understandable, the Linux kernel is one hell of a piece of software, so finding an issue like that is the typical “needle in haystack” story.
So long story short: for the Pi 3 family I’ve switched back to the Linux 4.14 kernel. I’ve did already all the work to run different kernels on specific hardware if necessary, so that work pays off now
Do we miss something with reverting back to an older kernel? Nope. All things I’ve changed to RoPieee’s kernel (it’s a custom build) are also present in the 4.14 kernel, so no worries there.
I’ll keep monitoring progress on the Pi foundation efforts and as soon as this issue is resolved we can switch back.
This post is rather technical, but there might be people out there who are interested in the details
@spockfish
Harry - using this old thread. I am new to using Pi4 as Roon/RoPieeXL. My music is plagued with pops every 20 seconds. Been spending too much time online and it looks like this is happening to some but not all. Is the Pi4 unit faulty or it it my Metrum Onyx DAC that is having troubles?
The last thing left to do is purchase a Pi2aes HAT and see if that saves the day. But that’s adding additional cost/equipment to the set up. I was under the impression that the Pi4 with its separate USB and power will perform better both in stability and sonics. With your experience and knowledge any insight on how I can make the random pops go away. Thanks,
I can assure you that’s not the case. First of all: I’m in depth up to speed with these issues and also with the remarks made in that link. It basically shows what more people have run into over the last years. Some of the fixes proposed in that article are already incorporated in RoPieee.
But, this is not the case here: you run a Pi 4 which has no issues on this front. So it must be something else. I’ve contacted the designer of the Onyx DAC (a friend of mine) which is also a RoPieee user. It works for him, but he’s sending over a device for me to test by myself.
In the mean time I would like to ask you the following:
disable all XL services.
update to the beta channel (you can do that from the ‘advanced’ tab).
do another test round with local content only
send me feedback with a detailed report: when it happened (timestamp), source material information (sample rate, bit depth) etc.
With this information I can try to see if I can match it with reports in your log files.
