Knowledge Base


AudioBox VSL Series: Hearing phasing/chorusing/echo while monitoring inputs through VSL


AudioBox 22VSL & AudioBox 44VSL

Input phasing or chorusing can be created on the AudioBox 22VSL & 44VSL if the Mixer knob is not turned completely clockwise to the VSL position and the AudioBox VSL is enabled. The simultaneous monitoring of the analog signal and the slightly latent AudioBox VSL signal creates this effect.


If you wish to use the analog monitoring available by using the Mixer knob to blend the input signal from your AudioBox with the Playback from your computer, open AudioBox VSL and disable it by click the On/off button in the upper left corner.


If you wish to use AudioBox VSL to create monitor mixes with effects, make sure the Mixer knob on the front-panel of the AudioBox 22/44VSL is turned completely clockwise to the VSL position.


PLEASE NOTE:  The VSL application will not be present if you are using the current versions of Universal Control drivers. The VSL app is only present on Legacy 1.3 and earlier versions of the AudioBox drivers.



All AudioBox VSL series interfaces (AudioBox 22/44/1818VSL)

Another cause of phasing or chorusing can be the simultaneous monitoring of the slightly latent AudioBox VSL input signal with the very latent input signal from your DAW. This effect will be far more dramatic as the signals can be up to a 50ms or more apart depending on the ASIO or Core Audio Buffer size that you’ve selected.


To remove the more latent signal coming from your DAW, you must disable input monitoring in your DAW. An easy way to do this is to simply mute the input channel in your DAW. This way, your DAW will still be recording the input signal, but it will not be playing back through the DAW returns inside AudioBox VSL.


It is important to mention that this problem will also occur when using analog monitoring on the AudioBox 22/44VSL.  This happens because you are blending the analog signal of your inputs with the playback from your DAW, so you must disable input monitoring in your DAW whether you create a monitor mix using the Mixer knob or AudioBox VSL.


PLEASE NOTE:  You will not be able to monitor via the AudioBox VSL application as it is not present when using the current Universal Control drivers for your AudioBox. 



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

>How to create a support ticket<



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