Updated May 20, 2022
A bus-powered audio interface is an audio interface that receives its power via a computer's USB port. The AudioBox USB 96 is an example of a "USB Bus-Powered" interface below. Notice on the back of the device that there is only a USB connection, there is no external power supply connection point. This means that the device draws its power solely from a computer, or via a powered USB hub. Bus-powered interfaces also rely on the computer to be properly grounded or you may experience additional noise.
In certain circumstances, the preamplifiers on a bus-powered interface may not provide sufficient gain to a signal generated by a dynamic microphone. (This is entirely dependent on the specifications of the dynamic microphone).
Dynamic Microphones can produce weak signals and they tend to require a lot of preamp gain when gain staging. This can sometimes introduce more background noise into the recording and can also increase the inherent noise floor of a bus-powered USB audio interface. If you find this to be the case then we recommend using a powered external preamp, more commonly referred to as an inline preamp. This active preamp can provide a gain boost to your dynamic microphone, allowing for a cleaner and less noisy signal.
Please Note: Condenser Microphones do not require an inline preamp as they are powered via phantom power (+48v), which is provided by the USB bus-powered audio interface.
Please Note: Engaging 48v while using a dynamic mic with an XLR-XLR cable can damage the mic
Please contact PreSonus Technical Support by creating a Support Ticket at My.PreSonus.com for further assistance.