21-Feb-2019, 17:43
Since the iMac Pro in late 2017, all Macs include an additional chip, the T2.
Apple initially said this was for security reasons but they have also transferred a lot other processing from intel to the T2.
They have transferred USB audio to the T2 (maybe they have transferred ALL USB and ALL Audio processing, I don't know)
The problem seems to stem from trying to keep time synchronisation between the Intel chip and the T2.
Approx. every 30 minutes a process called 'timed' runs to find out the exact correct time from Apple's servers. If the exact time on the Mac doesn't match the Internet time, things get re-synced. This can cause the unix kernel to stop and immediately restart the audio system, resulting in a brief glitch in sound over USB.
You can simulate this glitch by toggling on and off System Preferences -> Date & Time -> Set Date & Time automatically
If you have a Thunderbolt 3 Hub, connect the Devialet to a USB2 port on the hub and the problem goes way. All the USB2 processing is in the hub, the Mac is talking Thunderbolt to the hub so the processing is different.
More info
https://www.forum.rme-audio.de/viewtopic...66#p136666
https://appleinsider.com/articles/19/02/...face-users
https://www.head-fi.org/threads/what-a-l...t-14790143
https://forums.macrumors.com/threads/do-...i.2153841/
Apple initially said this was for security reasons but they have also transferred a lot other processing from intel to the T2.
They have transferred USB audio to the T2 (maybe they have transferred ALL USB and ALL Audio processing, I don't know)
The problem seems to stem from trying to keep time synchronisation between the Intel chip and the T2.
Approx. every 30 minutes a process called 'timed' runs to find out the exact correct time from Apple's servers. If the exact time on the Mac doesn't match the Internet time, things get re-synced. This can cause the unix kernel to stop and immediately restart the audio system, resulting in a brief glitch in sound over USB.
You can simulate this glitch by toggling on and off System Preferences -> Date & Time -> Set Date & Time automatically
If you have a Thunderbolt 3 Hub, connect the Devialet to a USB2 port on the hub and the problem goes way. All the USB2 processing is in the hub, the Mac is talking Thunderbolt to the hub so the processing is different.
More info
https://www.forum.rme-audio.de/viewtopic...66#p136666
https://appleinsider.com/articles/19/02/...face-users
https://www.head-fi.org/threads/what-a-l...t-14790143
https://forums.macrumors.com/threads/do-...i.2153841/
mac mini (2018, Latest MacOS, plain old iTunes) > no name USB cable or AIR3 over ethernet -> Devialet 200 -> Kimber 8TC -> KEF LS50
