Audio Monitors » 4 Channel

Product Description

The Bel BM-A1-4SHD is a high quality, 1U, 4-channel audio monitor/de-embedder suitable for operation in broadcast control rooms or OB vehicles where SDI is the standard video format. It is able to de-embed any group of 4 channels of audio from 3G/HD/SD SDI, and 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. 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 control.

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


The unit, built to a very high mechanical standard in a stainless steel 1U 19” enclosure, is designed to give the best possible isolation from external interference and vice versa, and is fully RoHS compliant.


High-quality 4 channel audio monitoring unit with SDI de-embedding


  • Metering and monitoring of 4 channels of audio    
  • 4-channel audio de-embedding from SDI sources, selectable in Groups   
  • Auto-sensing SDI inputs (SD/HD/3G)    
  • 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 
  • 200 mm depth chassis: ideal for OB applications