Knowledge Base


AudioBox VSL Series: Sync LED is Red not Blue


When the AudioBox VSL interface is running in Mac OS X without AudioBox VSL software installed, the USB Sync LED is Red, not Blue, why is this? 


On operating systems where AudioBox VSL software is installed and working, the USB Sync LED will illuminate Blue. 


AudioBox VSL Software is only available with the 1.3 Legacy Installer and is supported on Windows 7, Windows 8, Windows 10, Mac OS X 10.8, 10.9 and 10.10 only.


When the AudioBox 1818VSL, 44VSL or 22VSL is run on Mac OS X without AudioBox VSL software, the device is operating in what is referred to as "Class-Compliant" or (without drivers), the USB Sync LED will illuminate Red. 


As of Mac OS X 10.11 AudioBox VSL software is no longer supported and must be removed from the system so that AudioBox VSL can operate as a class compliant device. Read more about why here



Please contact PreSonus Technical Support by creating a Support Ticket at for further assistance.

>How to create a support ticket<



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