Applies to: Scarlett 18i20 3rd Gen

For all Scarlett 3rd Gen interfaces, apart from the 18i20, the sample can be changed in your recording software (DAW), in Focusrite Control or, from Audio MIDI Setup. The sample rate for the Scarlett 18i20 3rd Gen can only be changed from Focusrite Control or Audio MIDI Setup - not your DAW.

The reason for this is as follows;

The Scarlett interfaces are class compliant and use Apple’s Core Audio USB driver which is built into the operating system. When switching between different sample rate bands (i.e 44.1/48Khz, 88.2/96kHz and 176.4/192kHz), the number of channels that the Scarlett 18i20 3rd Gen presents to the operating system changes due to it's extensive channel count. For example, 4x channels of ADAT are lost at 88.2/96kHz and all ADAT channels are disabled at 176.4/192kHz.

Our firmware tells Core Audio that the channel count has changed when this occurs. We have to do this otherwise Core Audio will still think that there are, for example, 20 outputs available when the device is set to 88.2/96kHz, at which point audio won’t play back at all.

Due to a change in Core Audio in macOS 10.13 and above, the way it changes sample rate correctly between bands is now slightly different to before. We’ve had to make a change to Focusrite Control to facilitate this and whilst some DAW manufacturers have also added the change, many have not. This is the reason why the sample rate cannot be changed from within most DAWs with the Scarlett 18i20 3rd Gen.