Passive DI Box Omnitronic LH-055 1-Channel — passive direct box for instrument/line use, 1 input, balanced XLR output

The Omnitronic LH-055 is a passive 1-channel DI box that converts instrument or line-level signals to a balanced mic-level output suitable for mixers and PA systems. Designed for straightforward signal routing, it offers one input and a balanced XLR output, providing impedance matching and galvanic isolation typical of passive direct boxes. The unit includes a ground-lift function to reduce hum and ground-loop noise when connecting guitars, keyboards, or other line sources to professional audio equipment.

Advantages

The passive design requires no power supply and delivers reliable signal transfer with minimal coloration, making it suitable for both live and studio applications. The balanced XLR output improves noise rejection on long cable runs, while the ground-lift switch helps isolate unwanted hum from grounding differences. Compact and simple to operate, the LH-055 provides essential DI functionality without added complexity.

Suitable for

Key specifications

How to use

Connect the instrument or line-level source to the 1/4" input jack of the LH-055, then run a balanced XLR cable from the DI box output to the mixer or PA input. If hum or buzzing appears after connecting, toggle the ground-lift switch to break the chassis ground connection and reduce ground-loop noise. For low-output instruments, ensure the mixer preamp gain is set appropriately to achieve the required level without introducing excessive noise.

Recommendations

Use shielded cables for both the input and the balanced XLR output to maximize noise rejection. Place the DI box close to the instrument source to avoid long unbalanced cable runs, and verify gain staging at the mixer to maintain clean signal levels. Avoid using the DI box with active outputs that require power-dependent buffering unless the instrument explicitly supports passive DI connection.