Project Description

Bel Digital Group BM-A1-4SHD

Compact 4-channel audio monitor with 3G/HD/SD SDI de-embedding, plus AES3 and analogue inputs and outputs in a compact 1U 19” unit.

  • Metering and monitoring of up to 4 channels of audio
  • 4-channel audio de-embedding of any SDI group
  • Auto-sensing SD/HD/3G SDI inputs
  • Additional 8-channel sources: AES3id x 2 and analogue x 4
  • AES3id outputs of channels 1 to 4 of the selected source
  • Very simple to use: all primary functions have individual controls
  • Display for input status and unit configuration
  • 2 x full-range front panel speakers plus internal LF sub-woofer
  • Any channel may be monitored on either speaker, including combinations and groups
  • High resolution, tricolour LED meters with adjustable colour transition points and peak-hold facility
  • Four standard meter scales/ballistics, user selectable
  • Audio output levels are auto-adjusted for consistent volume when monitoring multiple channels
  • Compact 200 mm deep chassis, therefore ideal for OB and Flyaway applications

Bel Model BM-A2-4SHD MKII provides all the facilities of the BM-A1-4SHD, in a larger 2U chassis.


The Bel BM-A1-4SHD is a high quality, compact, 1U, 16-channel audio monitor/de-embedder suitable for operation in Master Control Rooms, OB vehicles and Flyaway systems where SDI is the standard video format. It is able to de-embed 4 channels of audio (1 group) from 3G/HD/SD SDI, display the levels on the front panel meters, and to provide stereo audio monitoring of any combination of the 4 channels.

The unit is very simple to use: all source selection and main monitoring setup is done from individual controls on the front panel without any necessity for menu navigation.

In addition to two auto-detecting 3G/HD/SD SDI inputs, the monitor has four balanced analogue inputs (XLR) and two AES3id BNCs. A re-clocked loop-through output is available for the selected SDI source providing a convenient and cost-effective method of switching SDI feeds to an external monitor. Channels 1 to 4 of the selected source are also routed to two AES3id outputs (providing de-embedding of any SDI audio group). In addition, the stereo audio monitor mix is available as a separate balanced feed at a pair of XLRs.

Audio levels are metered on four 26-segment tricolour LED bargraphs. User setup options allow a choice of four scales and ballistics (including BBC or DIN PPM, VU and AES/EBU), and also colour transition points and peak hold.

The audio quality is remarkably high for a 1U unit in addition to the front panel stereo speakers a third low frequency driver is mounted internally to provide an impressively extended low frequency response for such a compact monitor unit. Users have full flexibility in assigning any channel to left, right or both speakers (or neither), and automatic level attenuation compensates for monitoring multiple channels. A ¼” jack headphone output socket is provided on the front panel. When in use, the internal speakers are muted. Audio level at the rear panel analogue outputs may be configured from a setup menu either to be fixed or to follow the main volume/mute control.

The BM-A1-4SHD is fitted with a display screen, enabling easy device configuration and display of signal status information and volume.

The unit is built to a very high mechanical standard in a stainless steel 1U 19” enclosure that is only 200 mm deep. Warranty is for 3 years.


Bel Digital BM-A1-4SHD Brochure – PDF

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