The Mackie MDB-1A is an active direct box designed to connect a single instrument such as a guitar, bass, or keyboard to a microphone preamp for musicians and audio engineers in recording sessions, houses of worship, and live stage applications. It converts a high-impedance, instrument-level signal via its 1/4" TS unbalanced input to a low-impedance, mic-level output via its balanced XLR 3-pin jack. A 1/4" thru jack allows simultaneous connection to an amplifier or pedalboard.
A -20 dB pad reduces the input level to prevent distortion when using a high-gain source, and the ground-lift switch inhibits hum caused by ground loops. Additionally, there are switches for polarity and a 120 Hz high-pass filter. The Merge function allows the Thru jack to be used as a second, simultaneous input. Due to its active design, the MDB-1A operates on phantom power. A sturdy steel chassis enables confident use in the studio or on the road.
Input Connections 1 x 1/4" TS unbalanced
Output Connectors 1 x 1/4" TS unbalanced
1 x XLR 3-pin balanced
Input Impedance 330 kOhms unbalanced
Output Impedance 150 Ohms balanced
Impedance Ratio 2200:1
Pad -20 dB
High-Pass Filter 120 Hz
Frequency Response 20 Hz to 20 kHz (±0.5 dB)
Signal to Noise Ratio 90 dB
Dynamic Range 130 dB
Total Harmonic Distortion 0.02% at 1 kHz
Power Requirement 48 VDC phantom power
Current <4 mA DC
Construction Material Heavy-gauge steel chassis
Dimensions (H x W x D) 1.5 x 3.4 x 5.8" / 38 x 86 x 147 mm
Weight 0.8 lb / 0.4 kg
Package Weight 1.05 lb
Box Dimensions (LxWxH) 6.9 x 5.8 x 2.9"