BSS AR-133 Active DI Box

The AR-133 takes an instrument, line or amplifier-level source and sends a transformer-balanced, isolated feed to a console on XLR. Input attenuation switches between 0, -20 and -40 dB, which is what lets the same box sit in front of an acoustic guitar pickup one night and across a power amp output the next. A ground-lift switch on the output solves the loop problems that show up when it does.

It runs on phantom power and carries a 9 V PP3 battery as standby: if the console's phantom fails or gets switched off, the box changes over automatically and the show continues. Inputs are two parallel 1/4 in jacks plus a parallel XLR socket, so it also works as an unbalanced-to-balanced converter, and the second jack acts as a link for line bridging. The aluminium extrusion case with polyurethane end cheeks arches so cables can run back underneath from the end.