MACKIE MDB-1P - Professional single-channel passive DI box

MACKIE MDB-1P – Professional single-channel passive DI box

The Mackie MDB-1P is a single-channel passive DI box designed to convert unbalanced high-impedance signals (guitars, basses, keyboards) into balanced low-impedance outputs, ensuring clean, noise-free audio. Its “Built-like-a-Tank™” metal chassis construction offers durability on the road and in the studio. It includes a high-impedance 1/4″ input with a thru jack and –15 dB pad to prevent distortion from high-level sources, and a balanced XLR output with a ground lift switch to eliminate ground loops. No external power supply or batteries are required, making it a simple and reliable solution for live and studio applications.

Main features

• High impedance input: 1 × 1/4″ TS jack (140 kΩ) with parallel Thru output.
• Pad: –15 dB to protect against high level signals and maintain distortion-free performance.
• Balanced DI output: 1 × XLR male (400 Ω) with Ground Lift to suppress ground noise.
• Frequency range: 20 Hz – 20 kHz ± 0.2 dB.
• Dynamic: Signal-to-noise ratio of 128 dB.
• Distortion: THD ≤ 0.002% @ 1 kHz.
• Construction: Compact “Built-Like-A-Tank™” metal chassis.
• Dimensions: 38 × 86 × 147 mm.
• Weight: 0.36 kg.

User benefits

• Impedance Matching: Converts instrument signals to balanced lines without the need for external power.
• Signal Protection: The –15 dB pad and Thru output prevent clipping and allow you to continue sending your signal to the amplifiers.
• Noise Elimination: Ground Lift suppresses hum caused by ground loops in the system.
• Portability: Lightweight and compact design suitable for touring, rehearsals and studios.
• Reliability: High-quality passive circuitry with linear response and low distortion.

Use cases

• Connecting guitars, basses, or keyboards with active/passive pickups to consoles or microphone preamps.
• Injection of line sources (synthesizers, media players) into balanced PA systems.
• Recordings and live performances where a clean signal is required without latency or additional power supply.
• Fixed installations in studios, churches and conference rooms.

Frequently Asked Questions

• Does it need power? No; since it's passive, it doesn't require batteries or phantom power.
• Can I connect two amplifiers? Yes; the Thru output allows you to maintain the signal to the amplifier or pedalboard.
• How do I eliminate hum? Activate the Ground Lift switch on the XLR output to cut ground loops.
• Is the pad fixed? Yes; -15 dB protects against high-level signals without altering the tonal response.

Description for projects

Mackie MDB-1P passive DI box with high-impedance 1/4″ input and Thru, –15 dB pad, balanced XLR output with Ground Lift, 20 Hz–20 kHz, THD ≤ 0.002%, compact metal chassis, 38×86×147 mm, 0.36 kg.