Palmer BRIDGE 4A+ – Professional 4-Channel Active DI Box and Line Isolator Palmer BRIDGE 4A+ is a professional active DI box in a 19" rack format (1U), designed for stage, studio, broadcast and installation environments. It combines the functionality of an active DI box, line isolator and signal booster in a single compact device. With four independent channels, it offers maximum flexibility when working with multiple audio sources.

Each channel can operate independently as an active DI box, line isolator or signal booster. Combo inputs support both balanced XLR signals and unbalanced 6.3 mm jack connections, making the unit ideal for guitars, basses, keyboards, synthesizers and other line-level devices.

Transformer-based galvanic isolation effectively eliminates ground loops and unwanted noise, ensuring a clean and stable signal even in demanding live environments. Additionally, every channel features a dedicated Ground Lift switch to quickly remove hum and interference.

The BRIDGE 4A+ also allows boosting the signal level by +6 dB, +12 dB or +18 dB, making it possible to match various signal sources and optimize levels for professional audio systems.

A unique feature is Audio over Cat (AES72), allowing signals from all four channels to be transmitted via a single Cat network cable. This significantly simplifies cabling, reduces setup complexity and speeds up system installation.

Built into a rugged steel 19" rack enclosure (1U), the Palmer BRIDGE 4A+ is designed for reliability in touring rigs, professional studios and permanent AV installations. It is a versatile tool for sound engineers, technicians and system integrators who demand high signal quality and flexible connectivity.

Key features Active DI box / line isolator in 19" rack format (1U) 4 independent audio channels Each channel can operate as DI box, line isolator or signal booster Combo XLR / 6.3 mm jack inputs Two transformer-balanced XLR outputs per channel Galvanic isolation to eliminate ground loops and noise Ground Lift switch on each channel Selectable gain: +6 dB / +12 dB / +18 dB Audio over Cat (AES72) output for multi-channel transmission Solid 19" / 1U steel rack enclosure Power supply: 9–18 V DC Applications The Palmer BRIDGE 4A+ is ideal for live sound systems, recording studios, broadcast setups and AV installations. It ensures reliable, noise-free signal transmission over longer distances while simplifying complex audio routing setups.