So I’ve been testing zynthian v4.1 in various setups with raspberry pi 4 2GB. The thing is, I like reverbs and long delay feedbacks - and it’s something that make my zynth crack and pop quite a bit. Setting buffer size reduces artifacts but still not ideal. So my question is, will upgrading to RPi 4 4GB, improve things with my use case or not really? I don’t see any xruns, but the audio is crackling
The specific plugins that I like but give me pops and clicks are:
I don’t think increasing the memory on the Rpi will have any effect on the artifacts. I think they’re more a matter of the algorithms in the specific plug-ins you’re using.
If you ‘back off’ the amount of Reverb and feedback can you make the problem go away?
With dragonfly it’s almost constant, with delay - It’s OK for the most part, only when echo tail is really long - popping occurs.
I also have uConsole - which runs Raspberry Computer Module 4 with 4GB RAM.
On that machine I run desktop Raspberry OS > Reaper and loading plugins with full UI and dragonfly runs smoothly on top of surge xt with a heavy physical modeling patch loaded.
CM4 and rasberry pi 4 should have more or less same computing power, but it feels like zynthian has a lot less juice to offer when the only difference being 2GB of RAM
Could you temporarily run Zynthian on the uConsole machine perhaps with a USB sound card if it doesn’t already have one? Just to see if it fixes the problem. I guess Dragonfly Hall & Room reverb and GxTubeDelay might need more memory than you have. It seemed unlikely to me based on general results on this forum.
I think it would be a challenge to run zynthian on uConsole because it has a custom rasberry OS distribution to support screen, keyboard and on board audio and some kernel tweaks.
I was thinking to try USB interface with zynthian to see if that will make a difference
Yes, you can run htop in webconf’s terminal. I would be suprised if it is exhausting RAM but that should be indicated by htop as well as CPU usage. You could also run jack_cpu_load to show how heavily loaded jack is.
One of the most common causes of xruns and similar issues is poor PSU or cable. We recommend an official Raspberry Pi PSU for custom builds which have generally performed well.
Yep, the CPU and memory were OK while pops were present.
Regarding the indicators – the green heart was always green. But swapping power supplies and and cables does make a difference. I’ve found a combination that works for me for now, but I’ve ordered couple of new usb-c cables for further improvements hopefully.
I’ve been doing some DSP on RPi 3B+ before and I’ve gone through similar cycle with PSUs and cables. Unfortunately those are micro USB.
One question, if somebody has zynthian running RPi 4 with 2GB - can you load surge xt preset John Valentine - Grand Piano without x-runs? Probably polyphony needs to be reduced to 4-5 voices for it to work at all. I was really hoping to use this one, at least as a single instance to record and sample some chords for further use in the project.
Get an official Pi PSU. Really. The electronics is really good and the copper in the cable is twice thicker that any other cable i tested. And i tested quite seriously. I took 8 different cables, including the official RPi PSU (which i’ve to cut!!) and i measured the impedance. Also i measured the voltage quality of several PSUs, including ripple, dropping, etc, using a variable resistor and an oscilloscope. The official PSU from RBPi was the best in both categories:
Best cable
Best PSU (electronics) => less ripple and lower voltage drop at higher current
OK, long story short, I solved all the power troubles with 2$ micro to USB-C adapter.
Stacking reverbs and delays is not an issue anymore.
The reason for my cable swapping rituals is that I want my zynth to be portable. I have a very mighty power-bank capable of powering a laptop, but all suitable cables were only micro USB ones.
But with this adapter I get equally good performance on official Pi3 PSU, and the power bank. hurray!
Thanks everyone for the input.
But! Surge XT and John Valentine - Grand Piano - is still in my dreams, I see jack_cpu_load at 99 and xruns just playing one note. But RAM is OK, and cpu cores are at ~25% max. This happens with quite some surge presets. Could this be improved?
OK, I still feel a bit clumsy with zynthian but the whole weekend ahead to get around that clumsiness and record something 