Applies to: Clarett Range, Red Range
UPDATE - FIXED (28th March 2017):
We have tested macOS Sierra 10.12.4 and have confirmed that this update addresses an issue that caused consistently glitchy audio with Clarett/Red interfaces when used with a particular iMac model (Model Identifier: 17,1 – 2015 Retina 5K iMac).
We would therefore recommend that all affected customers update to this version by using the ‘Updates’ tab in the App Store application, after first checking that any important software that you use is also compatible with this version.
Any affected customers who have previously been sent alternative beta drivers by the Technical Support team should reinstall the release version of Focusrite Control from the Downloads section of our site after updating to macOS 10.12.4: https://focusrite.com/downloads
We would like to place on record our thanks to Apple for investigating and rectifying this issue.
If you encounter any problems with Clarett/Red interfaces after updating to macOS Sierra 10.12.4 then please Contact Technical Support.
Archived information about the issue can be found below:
This problem manifests as glitchy/distorted audio when using sample rates above 44.1kHz, when used in conjunction with the latest update to El Capitan (version 10.11.5) and later (including macOS Sierra) and a particular iMac Model (Model Identifier: iMac 17,1. iMac Retina 5K, 27-inch, Mid or Late 2015).
NOTE: It appears that once a system has been updated to 10.11.5, reverting to an older version of the OS from a backup does NOT appear to rectify the problem.
If you're unsure which specific Mac model you have, you can find this information by clicking the Apple Logo in the top left corner of the screen, then going to About This Mac > System Report. The 'Model Identifier' appears in the Hardware tab.
This issue tends to affect all sample rates above 44.1kHz, but you should get clear audio when playing back and recording using 44.1kHz.