The Palmer BRIDGE 4A+, is a multifunctional device: each of the four channels can be used independently as an active DI box, a line isolation box, or a booster. The input combo socket accepts unbalanced and balanced signals. The outputs are designed as two transformer-balanced XLR sockets per channel (one on the front and one on the rear).

The galvanic isolation via transformer eliminates hum loops, and the ground lift switch can also be used to eliminate noise and interference that occurs with already balanced input signals. The Palmer BRIDGE 4A+ reliably eliminates any hum – and when connecting unbalanced equipment, the signal is also balanced.

If necessary, the signal level can be raised in three stages by 6dB, 12dB or 18dB. The audio over Cat output allows the signals of all 4 channels to be routed via a single Cat cable. This saves material, space, and time.

The BRIDGE 4A+ line isolation box is a universal problem solver for eliminating ground loops. Whether it’s at home, at lectures, in the rehearsal room, on stage, in clubs, or at large events – the Palmer BRIDGE 4A+ ensures a clean sound without interference anywhere.

Product Specifications:

Product type: DI boxes, Line isolators

Type: active

Transformer isolated: yes

Channels: 4

Inputs: 4

input type: balanced/ unbalanced

Input connectors: 6.3 mm jack, XLR

Number of outputs: 4 (+ 4 parallel XLR outs + AoC)

THRU outputs/channel: 0

Output type: balanced

Output connectors: RJ45, XLR

Output attenuation (PAD): 0 dB / 20 dB

Cabinet material: sheet steel

Width: 482 mm

Width: 19 “

Depth: 90 mm

Height: 44 mm

Height: 1 U

Weight: 2.1 kg

Ground lift switch: yes

Operating voltage: 9 V – 18 V

Power consumption: 2 W

Additional Features: 6/12/18 dB gain, AoC output with ground lift, power LED

Ambient temperature during operation: -20 – 70 C

Relative Humidity: < 80% (non-condensing)

Accessories (included): external power supply PW9V

Max. input level (< 1% THD, 20 Hz): +10 dBu

Max. input level (< 1% THD, 1 kHz): +16 dBu

Max. output level (<1% THD, 20 Hz - 20kHz): +7 dBu

Frequency response (0,2 dB, relative 1 kHz): 20 Hz – 20 kHz

Input impedance (1 kHz): 20 kOhm

Output impedance (1 kHz): 84 Ohm(s)

THD + N (30 Hz, +4 dBu, unity, unweighted): < 0.0023%

THD + N (1 kHz, +4 dBu, unity, unweighted): < 0.0009%

IMD (SMPTE) (60 Hz / 7 kHz, 4:1, +4 dBu): < 0.0018%

SNR (+4 dBu, 22 kHz BW, unity, unweighted): 105 dB

Transformer ratio: 10: 1