Samson S-MAX MDA1 Single-Channel Active Direct Box - Manual (Page 6)

Powering the MDA1
The MDA1 can operate on a single 9 Volt battery or standard 48 volt phantom power. Whenever phantom
power is present on the XLR cable that is connected to the Balanced Output, the MDA1 plus will auto-
matically switch to phantom power and disconnect the 9 Volt battery. In fact, when the Battery switch is
in, the MDA1 will sense the voltage and select which is greater. The Phantom/Battery switch can be used
to turn off the battery power when the unit is not in use.