I’ve built my V3 kit in April this year and everything worked fine and as expected (considering a Raspi 3) including Pianoteq Stage and PD patches.
The OS version I used until now was “2020-04-30-zynthianos-buster-lite-1.0.0”. I recently decided to catch-up with an update to the current “latest-stable” (2020-09-06) release. After flashing the SD-card I enabled WiFi and chose the “Kit V3 Pro” hardware and audio parameters.
From now on the sounds of every synth engine produce erratic but somewhat repeating digital crackling sounds. There are no xrun or power warnings visible and checking logs and CPU load or temperature doesn’t hint any problems. The crackling can be forced even more by rotating the encoders or fiddeling on the touch screen. The crackles stop after the sound from e.g. ZynAddSubFX is finished playing (release end, no more reverb tail).
Could there be any problems I produced building my Kit 3 hardware, that are getting obvious now?
Sounds like a timing issue. You could try reseating the soundcard and whilst it is off, check for any debris on the card, e.g. give it a clean with a dry, stiff brush.
No succes. I dismantled everything, scrubbed and brushed the headers and connectors even with some isopropanol - still the same crackling. I discovered the somewhat obvious: All sound errors disappear, when I start the Zynthian without the display/encoder panel connected. And when I leave the middle MIDI board unconnected while HIFI-Berry and display still on, it gets even worse, like digital static noise. Don’t know, if that’s of importance. Maybe I’ll stay with the older OS version for now…
Does the noise vanishe when you use the old SD image? In such a case, could you check you are using the right driver? What is your sound card and what is your configuration?