Signals from electronic instruments such as guitars, keyboards and similar sound sources generally have a low level, high im- pedance output, which will not interface with the low impedance balanced input found on professional sound mixing con- soles. Furthermore these signals cannot be driven up long cable lengths without serious loss of level and degradation.

The BSS Audio AR-133 Active DI Box converts this signal to a more suitable form without interfering with or modifying the signal at the instrument source, and should provide freedom from ground and power line related problems. Passive DI boxes have limited applications as they will inevitably affect the signal source for guitar type applications, and can also have an insertion loss of around 20dB. The only safe and predictable way to provide direct feeds from instruments or other sources is by using an Active DI box utilising an input amplifier driving an output transformer.

The BSS Audio AR-133 Active DI Box provides a transformer balanced and isolated feed from a source input via a 1/4" TRS jack or 3-pin XLR-type connector. The unit includes phantom power and battery supplies as standard. Should the phantom power from the console fail or be accidentally switched off, the AR-133 automatically switches over to the internal 9V battery providing uninterrupted use.

The unit is housed in a rugged aluminium extrusion case, with robust polyurethane end-cheeks which give the AR-133 a very distinctive look. Input connectors are both 1/4" jack sockets and an XLR socket, the latter meaning that the AR-133 can be used to convert unbalanced signals to a balanced output on XLRs throughout. The arched case allows cables to run back underneath the unit from the end for neat cable management.

Input attenuation is 0, -20 or -40dB, making the box suitable for instrument, line or amplifier levels on inputs. On the output side, a ground-lift switch is provided for quick solutions to ground-loop problems. The AR-133 uses an enhanced version of the same audio path as the AR-116, now regarded by many people as a reference standard. The sound quality is legendary, particularly on acoustic and bass guitars. Numerous applications can be satisfied by the AR-133. For example, as well as the traditional guitar use, the AR-133 can be used with keyboards, DJ consoles, amplifier outputs, and other electronic sources.