The DB-1A from Tapco is an active direct box that solves many of the level issues that arise when connecting various pieces of electronic gear together.
Different piece of equipment have differing signal level inputs and outputs. For example, the output of electric guitars and basses does not match the input level a mixer is looking for to be able to provide a healthy output. Additionally, keyboards generally have unbalanced outputs that, if used with long cable runs, can induce noise in the signal.
The DB-1A is able to solve many of these problems. The unit is either powered by batteries or from phantom power provided by a mixer.
Converts unbalanced line level signals to balanced microphone level output
Provides signal and impedance matching for the direct connection of instruments to amplifiers and mixers
"Thru" jack allows the unbalanced signal to be sent to an onstage amplifier while the balanced signal is sent to a mixer
Ground Lift switch helps eliminate hum and buzz problems in musical instrument hookups
Allows the use of long cables without high frequency loss
Can be powered either internally via two 9V batteries (not included) or externally by phantom power from a mixer