Sonifex CM-BH4WX - Belt-Pack 4-Wire Headphone Amp

The CM-BH4W is a portable, battery powered 4 wire communication unit for use in a multitude of TV and radio broadcasting applications.

Transformer Balanced I/O

The CM-BH4W uses audio transformers at its input and output, providing galvanic isolation from outside interference, ensuring your communications are loud and clear, every time.

4-Wire And IFB Modes

In 4-wire mode, the unit acts as a 2-way intercom, with input audio routed to the headset earpiece, and microphone audio is routed to the output upon pressing the talk button. The output level is maintained at +2dBu peak level by a built-in AGC. In IFB mode, the input audio is routed to the output, and is interrupted by the microphone signal when the talk switch is pressed. The talk switch can easily be converted from momentary to latching operation to suit your application.

Low Battery Warning

A low battery warning LED flashes when the 9V PP3 battery has depleted to 6V, giving plenty of notice to swap the battery. In addition, the CM-BH4W automatically switches off when the headset jack is removed, and the low power circuitry gives up to 150 hours use from a single alkaline 9V PP3 battery.


Technical Specification For CM-BH4W/X

Mic In to Line Out

Mic Input Impedance:
1k5Ω Unbalanced for 200Ω dynamic microphone

Limiter Input Threshold:
-60dBu

Line Output Level:
+2dBu

Line Output Impedance:
150Ω Transformer balanced

Line In to Headphone Out

Line Input Impedance:
>10kΩ Transformer balanced

Input Gain/Volume:
Adjustable off to +10dB

Maximum Input Level:
+24dBu

Maximum HP Output Level:
+7dBu (ref 9V battery voltage, <1% THD, 100Ω load)

Minimum HP Impedance:
100Ω

Connections

Line Input:
1 x XLR 3 pin female socket (balanced)

Line Output:
1 x XLR 3 pin male plug (balanced)

Headset (CM-BH4W):
1 x ¼” (6.35mm) mono unbalanced jack socket

Headset (CM-BH4WX):
1 x XLR 4 pin male plug (balanced)

Equipment Type

CM-BH4W:
Belt-pack 4-wire headphone amplifier

CM-BH4WX:
Belt-pack 4-wire headphone amplifier with 4 pin XLR headset connector

Physical Specification

Dimensions (Raw):
12.5cm (W) x 6.7cm (D) x 4.8cm (H)
4.9” (W) x 2.6” (D) x 1.9” (H)

Dimensions (Boxed):
23cm (W) x 13cm (D) x 8cm (H)
9.1” (W) x 5.1” (D) x 3.1” (H)

Weight:

Nett: 0.3kg 
Gross: 0.4kg

Nett: 0.6lbs
Gross: 1.0lbs