Palmer BRIDGE 4P – passive 4-channel 19" DI box

In live sound and studio environments, signal integrity is critical. The Palmer BRIDGE 4P is a professional 4-channel DI box in a 19" rack format, designed to deliver clean, balanced signals while minimizing noise, hum, and interference. It allows proper impedance matching for instruments such as electric guitars, basses, keyboards, and synthesizers, ensuring reliable signal transfer to mixing consoles, stage boxes, or audio interfaces. Thanks to its passive design, it operates without external power, making it a dependable solution for both touring and fixed installations.

Key features

This unit provides four fully independent channels housed in a rugged 1U 19" rack enclosure. Each channel includes a 6.3 mm jack input, a THRU output for signal routing to amplifiers, and a balanced XLR output. Additionally, the BRIDGE 4P features Audio over Cat (AoC) via an RJ45 connector, allowing all four channels to be transmitted through a single Cat5e (or higher) cable, significantly simplifying cable management and stage setups.

Clean signal and maximum control

High-quality transformers ensure galvanic isolation, effectively reducing ground loop issues and unwanted noise. With a transformer ratio of 1:10, the unit provides optimal impedance matching and signal balancing for professional audio applications. Each channel includes a switchable attenuation pad (0 dB / -30 dB), enabling safe handling of both instrument-level and higher-level signals without distortion. A dedicated ground lift switch per channel allows quick adaptation to various electrical environments.

The wide frequency response of 20 Hz to 20 kHz ensures accurate signal reproduction across the entire audio spectrum, preserving both low-end depth and high-frequency clarity. Extremely low distortion values contribute to transparent sound quality, making the unit suitable for demanding live and studio applications. By consolidating four DI channels into a single rack unit, the BRIDGE 4P helps maintain a clean and organized setup while saving valuable space.

Applications

The Palmer BRIDGE 4P is ideal for live performances, rehearsal spaces, recording studios, broadcast environments, and permanent installations. It is perfectly suited for connecting guitars, basses, keyboards, digital pianos, and synthesizers to professional audio systems. The THRU outputs allow simultaneous routing to stage amplifiers, making it especially useful in live performance scenarios. Sound engineers, technicians, and musicians will appreciate its reliability, compact form factor, and ease of integration into existing setups.

Technical specifications

• Product type: DI box
• Design: passive
• Channels: 4
• Transformer isolated: yes
• Inputs: 4
• Input connectors: 6.3 mm jack
• Input attenuation: 0 dB / -30 dB
• Outputs: XLR, THRU, RJ45 (Audio over Cat)
• THRU outputs per channel: 1
• Input impedance: 27 kOhm
• Output impedance: 30 Ohm
• Frequency response: 20 Hz – 20 kHz
• Max input level: +21 dBu (20 Hz), +25 dBu (1 kHz)
• THD: <0.029% (30 Hz), <0.0006% (1 kHz)
• IMD (SMPTE): <0.0012%
• Transformer ratio: 1:10
• Ground lift: yes
• Operating temperature: -20°C to 70°C
• Humidity: <80% (non-condensing)
• Format: 19" / 1U
• Dimensions: 482 x 90 x 44 mm
• Weight: 1.92 kg

Construction and durability

The device features a robust steel enclosure designed for demanding professional use. Its standard 19" rack format ensures easy integration into flight cases and installation racks. The durable build and high-quality connectors make it suitable for frequent transport and long-term operation in various environments.

Included in the box

• 1 x Palmer BRIDGE 4P passive 4-channel DI box

Summary

The Palmer BRIDGE 4P is a reliable and space-saving solution for managing multiple audio signals with clarity and precision. With four independent channels, transformer isolation, THRU outputs, and Audio over Cat functionality, it provides flexibility and professional performance in both live and studio environments. Its passive design ensures maximum reliability, making it an excellent choice for demanding audio setups.