bel Digital Audio BMA2-4SHD User manual

BMA2-4SHD
audio monitor/alarm system
User’s Guide Version 0.8 2/2/2006

BEL DIGITAL AUDIO BMA2-4SHD
2006 BEL (Digital Audio) Ltd
BEL (Digital Audio) Ltd. has made every effort to ensure the accuracy of information contained within
this document which is nevertheless supplied for information purposes only and does not constitute
any form of warranty or guarantee.
All trademarks acknowledged.
The information in this document is subject to change without notice.
Bel Digital Audio Ltd.
Unit 3
Horwood Court
Bletchley
Milton Keynes
Bucks
MK11RD
Tel: [phone]
Email: [email protected]
Web: www.beldigital.com
Manual prepared by AirdServices http://brianaird.members.beeb.net

BEL DIGITAL AUDIO BMA2-4SHD
2006 BEL (Digital Audio) Ltd
C
Co on nt te en nt ts s
INTRODUCTION 1
Main features 1
OPERATION 3
SELECTING SOURCES 3
USING ALARMS 3
Alarm arming 4
BARGRAPH SCALES 6
INSTALLATION 7
CONNECTOR I/O 7
Alarms connector pinout 7
RS232 Host interface connector pinout 8
CONFIGURATION 9
Adjusting analog input level 10
Adjusting audio monitor output level 11
Adjusting alarm tone 12
Adjusting bargraph break-points and ballistics 13
Inserting bargraph graticules 16
USING MONITORMX SOFTWARE 17
Main Features 17
MONITORMX SOFTWARE OPERATION 18
Running MonitorMx software for the first time 18
Viewing connected units 18
Configuring alarms 19
Source selection 20
Meter characteristics 20
Disabling local control 20
MONITORMX SOFTWARE INSTALLATION 21
Minimum pre-requisites: 21
Serial cable 21
BM-A SERIES SERIAL PROTOCOL 22

BEL DIGITAL AUDIO BMA2-4SHD
2006 BEL (Digital Audio) Ltd
OVERVIEW 22
Frame format 22
COMMANDS 24
DATA FORMATS 25
PROBLEM SOLVING 30
Sample problems and their solutions 31
SPECIFICATION 32

BEL DIGITAL AUDIO BMA2-4SHD Introduction
2006 BEL (Digital Audio) Ltd 1 Version 0.8
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In nt tr ro od du uc ct ti io on n
The BMA2-4SHD is a professional audio monitor/ alarm system housed in a 2U rack.
The unit features two speakers and an analogue line output. Audio input signals can be in
the form of analog, AES (SPDIF) and SDI embedded data. The BMA2-4SHD accepts audio
inputs in groups of 4 channels from the selected source and can direct any two from these to
the speakers. De-embedded audio can be selected from either an SD input or an HD input.
Alarms can be set to monitor audio-over-level, audio-loss and sustained anti-phase.
Main features
•1 x SD and 1 x HD video inputs
•Auto PAL/NTSC detection
•Handles SDI embedded (groups 1 – 4), 2 x AES or 2 x analog audio input pairs
•Option for balanced XLR or unbalanced BNC digital audio I/O
•High-quality, high SPL audio reproduction with soft limiting
•4 x tri-color bargraphs with six standard scales and ballistics, adjustable color
transition points and peak-hold facility
•Alarms for audio loss, over-level and sustained anti-phase
•Line level analog audio output of sources directed to loudspeakers
•Headphone connector with speaker mute
•Individually user-calibrated audio level inputs/outputs and metering
•Windows GUI and separate RS232 protocol for remote control of all alarm functions
and audio/video switching
•TTL port for alarms reset and remote alarms indication

BEL DIGITAL AUDIO BMA2-4SHD Introduction
2006 BEL (Digital Audio) Ltd 2 Version 0.8
The BEL Digital BMA2-4SHD
All audio inputs are converted to 24 bit digital form and AES inputs are re-sampled using
sample rate converters where necessary at an internally generated 48kHz. If embedded
audio from a serial digital video input is selected, the sampling clock recovered from this is
used instead.
The audio source switch selects which audio source is available to the speaker selectors and
bargaphs.
The left and right speaker switches select which of the currently selected four audio channels
is available at the speakers after three stages of analog processing.
The selected audio is first passed through factory preset equalization filters. Then electronic
level control is then applied with the balance and volume knobs providing control voltages.
Finally a soft limiter is used to protect the speakers. The headphone output is taken before
the limiters and mutes the speakers when used. Alarm tone is added just before the speaker
output.
A soft mute is applied to the audio when any select switches are used to reduce glitches.
Note: The alarm tone level control is mounted inside the unit and is not available from the front
control panel.

BEL DIGITAL AUDIO BMA2-4SHD Operation
2006 BEL (Digital Audio) Ltd 3 Version 0.8
O
Op pe er ra at ti io on n
The front panel user interface consists of 6 rotary controls, an alarms switch and four
bargraphs. There is a video selector a headphone output, two LEDs for sustained anti-phase,
and seven additional status LEDS.
The BMA2-4SHD front control panel
Selecting sources
The audio source switch selects which group of audio sources is available to the speaker
selectors and bargaphs. The possible choices are Analog, AES A + B or SDI embedded
groups 1 to 4 from either the SD or HD inputs as determined by the video source switch.
The REM or remote position of the video source switch forces BMA2-4SHD to be controlled
from the serial port. Any serial commands will then take precedence over the front control
panel.
Note: If a video source is selected using the video source switch, that input will provide de-
embedded audio. If the video source switch is in the REM position with no active remote
video selection and an SDI audio group is selected, then audio groups 1 to 4 are taken
from the HD input.
Using alarms

BEL DIGITAL AUDIO BMA2-4SHD Operation
2006 BEL (Digital Audio) Ltd 4 Version 0.8
BMA2-4SHD can provide warnings of several input signal conditions:
Signal condition Notes Alarm indication
Audio loss
The currently selected four audio
channels are monitored for
persistent under-level. An alarm is
generated when an input is < -30dB
(-50dB for AES meter) for more than
15 seconds.
Audio tone
Bottom bargraph
segment flashes amber
TTL/serial alarm
Audio-over-level The currently selected four audio
channels are monitored for transient
over-level. An alarm is generated
immediately when the first red
segment of the relevant bargraph is
illuminated.
Audio tone
Bottom bargraph
segment flashes red
TTL/serial alarm
Audio anti-phase Audio pairs 1&2 and pairs 3&4 are
monitored for sustained anti-phase.
Audio tone
Appropriate phase LED
illuminates
TTL/serial alarm
Button functions
Note: The over-level alarm threshold can be adjusted by moving the red bar transition point.
To prevent the anti-phase detector from generating intermittent alarms, only persistent
anti-phase conditions are used to raise an external alarm or generate an audio tone.
An alarm is generated when an anti-phase condition exists for more than 10 seconds.
Alarm arming
No alarms are generated unless alarm functions have been ‘armed’.
The front panel alarm toggle switch has four functions:
1. Upper position held – ALARM RESET - any armed input alarms are cleared
2. Upper position momentary – resets bargraph peak-level indicators
3. Middle position – OFF/MUTE - the internal audible alarm is muted
4. Lower position – SET - alarm functions are selectively armed
The switch must be held in the upper ALARM RESET position for more than 3 seconds for a
reset to occur.
In the lower SET position the inputs currently active are automatically detected and the
appropriate alarms are selectively enabled. The unit is then set to monitor only the active
inputs. The SET function can be disabled using a serial command.

BEL DIGITAL AUDIO BMA2-4SHD Operation
2006 BEL (Digital Audio) Ltd 5 Version 0.8
If alarms are present, moving the toggle switch to the center position will stop the audible
alarm, but retain the visual alarm indications and TTL/serial alarm outputs. The switch must
be held in the ALARM RESET position for more than 3 seconds for all alarms to be cleared.
The center position is the recommended position when alarm indication is not required.
Note: Restoring input signals to normal condition does not clear alarms.

BEL DIGITAL AUDIO BMA2-4SHD Operation
2006 BEL (Digital Audio) Ltd 6 Version 0.8
Bargraph scales
The following bargraph ballistics may be selected using internal switches.
Scale type Range Attack Fallback
AES/EBU: 60dB (0 to -60dB) 1ms 1.5Sec per 20dB decay
DIN PPM: 55dB (+5 to -50dB) 10mSec 1.5Sec per 20dB decay
VU: 23dB (+3 to -20dB) 300mSec 300mSec
BBC PPM: +12 to-12dB - mark 7 to 1 10mSec 2.85Sec - mark 7 to 1
VU EXT: 80dB (+20 to -60dB) 300mSec 300mSec
NORDIC: 54dB (+12 to -42dB) 5mSec 1.7Sec per 20dB decay
BMA2-4SHD scale ballistics
Stick-on scale graticules, which may be applied to the space between the front-panel
bargraphs, are supplied with the machine.
BMA2-4SHD scale graticules
Note: Bargraph color transition points and peak hold decay may also be adjusted
internally.
Refer to the Configuration chapter for switch settings and graticule fitting
instructions.

BEL DIGITAL AUDIO BMA2-4SHD Installation
2006 BEL (Digital Audio) Ltd 7 Version 0.8
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In ns st ta al ll la at ti io on n
The BMA2-4SHD 2U may be installed in 19 inch bays with 300mm depth including typical
cable and connector depth. Ventilation is by natural convection and there are vents at each
side and on the top and bottom covers of the unit.
Frames may be installed into bays, providing airflow through these vents is not impeded.
The 2U BMA2-4SHD showing ventilation slots
Connector I/O
All connections, with the exception of the headphone socket, are provided on the rear panel.
Video inputs use BNC connectors and all data connections use 9 way ‘D’ type connectors.
The BMA2-4SHD balanced audio version rear view
Digital audio I/O may be supported with either XLR connectors for balanced audio or BNCs
for unbalanced audio, depending on the BMA2-4SHD version.
Alarms connector pinout

BEL DIGITAL AUDIO BMA2-4SHD Installation
2006 BEL (Digital Audio) Ltd 8 Version 0.8
Connector type: 9 way sub-D female
Pin Description
1 Audio alarm out (TTL compatible active high)
2 Not connected
3 Reset in (TTL compatible active low)
4 GND
5 Not connected
6 Not connected
7 Not connected
8 Not connected
9 Not connected
Note: TTL outputs can supply up to 10mA.
RS232 Host interface connector pinout
Connector type: 9 way D female
Speed: 9600 bps
Format: 8 bit, no parity, 2 stop bits
Pin Description
1 Not connected
2 Rx (from host)
3 Tx (to host)
4 Not connected
5 GND
6 Not connected
7 Not connected
8 Not connected
9 Not connected
Note: A null-modem lead will be required to interface to a PC. See the MonitorMx
software chapter for more details.

BEL DIGITAL AUDIO BMA2-4SHD Configuration
2006 BEL (Digital Audio) Ltd 9 Version 0.8
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Co on nf fi ig gu ur ra at ti io on n
Access to BMA2-4SHD internal adjustments is obtained with the top removed.
BMA2-4SHD internal adjustments
The following adjustments may be made:
•Monitor output level – SW3/potentiometers main board
•Analog input level – SW4 and SW5/potentiometers main board
•Bargraph settings – SW1 and SW2 main board, near power supply
•Alarm tone – RV7 main board
Warning: Configuration instructions are for trained personnel. To avoid dangerous electric
shock, do not remove any covers or carry out adjustments unless qualified to do so.

BEL DIGITAL AUDIO BMA2-4SHD Configuration
2006 BEL (Digital Audio) Ltd 10 Version 0.8
Adjusting analog input level
In the following tables, ON is obtained with a switch lever in the DOWN position. The
adjustments are located on the main board under the output sub-board.
Analog input adjustments – 0dB setting shown
SW4 Anlg
Input
Setting when ON
1 1 0 dB (0dBu in = 0 on analog scale)
2 1 4 dB (+4dBu in = 0 on analog scale)
3 1 8 dB (+8dBu in = 0 on analog scale)
4 1 Variable – adjacent pot* –10 to +12 dB
5 2 0 dB (0dBu in = 0 on analog scale)
6 2 4 dB (+4dBu in = 0 on analog scale)
7 2 8 dB (+8dBu in = 0 on analog scale)
8 2 Variable – adjacent pot* –10 to +12 dB
SW5 Anlg
Input
Setting when ON
1 3 0 dB (0dBu in = 0 on analog scale)
2 3 4 dB (+4dBu in = 0 on analog scale)
3 3 8 dB (+8dBu in = 0 on analog scale)
4 3 Variable – adjacent pot* –10 to +12 dB
5 4 0 dB (0dBu in = 0 on analog scale)
6 4 4 dB (+4dBu in = 0 on analog scale)
7 4 8 dB (+8dBu in = 0 on analog scale)
8 4 Variable – adjacent pot* -10 to +12 dB
Note: It is intended that only one switch lever is set ON for each analog input.
The ON position is obtained with a switch lever in the direction of the arrow
(downward in the above drawing).
*Clockwise rotation increases gain.

BEL DIGITAL AUDIO BMA2-4SHD Configuration
2006 BEL (Digital Audio) Ltd 11 Version 0.8
Adjusting audio monitor output level
In the following tables, ON is obtained with a switch lever in the DOWN position. The
adjustments are located on the main board under the output sub-board.
Analog monitor output adjustments – 0dB setting shown
SW3 Monitor
Output
Setting when ON
1 Left 0 dB (0 on analog scale = 0dBu on output)
2 Left 4 dB (0 on analog scale = +4dBu on output)
3 Left 8 dB(0 on analog scale = +8dBu on output)
4 Left Variable – adjacent pot* 0 to +12 dB
5 Right 0 dB (0 on analog scale = 0dBu on output)
6 Right 4 dB (0 on analog scale = +4dBu on output)
7 Right 8 dB(0 on analog scale = +8dBu on output)
8 Right Variable – adjacent pot* 0 to +12 dB
Note: It is intended that only one switch lever is set to ON for each monitor output.
The ON position is obtained with a switch lever in the direction of the arrow
(downward in the above drawing).
*Clockwise rotation increases gain.

BEL DIGITAL AUDIO BMA2-4SHD Configuration
2006 BEL (Digital Audio) Ltd 12 Version 0.8
Adjusting alarm tone
The alarm tone adjustment is located near the analogue input controls.
Alarm tone adjustment
Control Effect of clockwise rotation
Alarm tone Decrease alarm level

BEL DIGITAL AUDIO BMA2-4SHD Configuration
2006 BEL (Digital Audio) Ltd 13 Version 0.8
Adjusting bargraph break-points and ballistics
The adjustments, SW1 and SW2 are located near the power supply.
BMA2-4SHD bargraph adjustments
SW1-8 AES to analog adjust
OFF
ON
-18dBFS = 0 on analog scale
-20dBFS = 0 on analog scale
The –18dB and –20dB settings define the correspondence between AES input level and the
0 mark on an analog scale. This allows analog scales to be used with digital signals.
Note: When digital inputs are used with an analogue scale the line outputs will be less than
that indicated on the meters since the digital to analogue converters clip at +15 dB.
The effective loss is -3dB when the 18 dB position is selected and -5dB when the 20 dB
position is selected.
SW1-7 SW1-6 Peak hold decay
OFF OFF None (Off)
OFF ON 3 seconds
ON OFF 7 seconds
ON ON Indefinite
SW1-5 SW1-4 SW1-3 Scale type
OFF OFF OFF AES
OFF OFF ON DIN
OFF ON OFF VU
OFF ON ON BBC
ON OFF OFF Extended VU
ON OFF ON NORDIC
ON ON OFF No scale
ON ON ON No scale
Note: The OFF position is obtained with a switch lever in the direction of the arrow, (to the
right in the above drawing).

BEL DIGITAL AUDIO BMA2-4SHD Configuration
2006 BEL (Digital Audio) Ltd 14 Version 0.8
Each bargraph has 53 tri-color segments. The top and bottom segments are reserved as
alarm indicators leaving 51. Up to 31 of the remaining top most segments may be colored
red. Up to 31 of segments from the end of the red zone downward may be colored amber.
The remaining segments (if any) are always green.
Choosing how many segments are colored red from the top of the bargraph sets the ‘red
zone’. Select from none to 31 using SW1-2, SW1-1, SW2-8, SW2-7 and SW2-6 as follows:
SW1-2 SW1-1 SW2-8 SW2-7 SW2-6 Segment from bargraph top
OFF OFF OFF OFF OFF None
OFF OFF OFF OFF ON 1
OFF OFF OFF ON OFF 2
OFF OFF OFF ON ON 3
OFF OFF ON OFF OFF 4
OFF OFF ON OFF ON 5
OFF OFF ON ON OFF 6
OFF OFF ON ON ON 7
OFF ON OFF OFF OFF 8
OFF ON OFF OFF ON 9
OFF ON OFF ON OFF 10
OFF ON OFF ON ON 11
OFF ON ON OFF OFF 12
OFF ON ON OFF ON 13
OFF ON ON ON OFF 14
OFF ON ON ON ON 15
ON OFF OFF OFF OFF 16
ON OFF OFF OFF ON 17
ON OFF OFF ON OFF 18
ON OFF OFF ON ON 19
ON OFF ON OFF OFF 20
ON OFF ON OFF ON 21
ON OFF ON ON OFF 22
ON OFF ON ON ON 23
ON ON OFF OFF OFF 24
ON ON OFF OFF ON 25
ON ON OFF ON OFF 26
ON ON OFF ON ON 27
ON ON ON OFF OFF 28
ON ON ON OFF ON 29
ON ON ON ON OFF 30
ON ON ON ON ON 31
Note: It is not possible to set 31 red and 31 amber segments, since there are only 51
segments for level display purposes.

BEL DIGITAL AUDIO BMA2-4SHD Configuration
2006 BEL (Digital Audio) Ltd 15 Version 0.8
Choosing how many segments are colored amber from the end of ‘red zone’ sets the ‘amber
zone’. Select from none to 31 using SW2-5, SW2-4, SW2-3, SW2-2 and SW2-1 as follows:
SW2-5 SW2-4 SW2-3 SW2-2 SW2-1 Segment from last RED ZONE
OFF OFF OFF OFF OFF None
OFF OFF OFF OFF ON 1
OFF OFF OFF ON OFF 2
OFF OFF OFF ON ON 3
OFF OFF ON OFF OFF 4
OFF OFF ON OFF ON 5
OFF OFF ON ON OFF 6
OFF OFF ON ON ON 7
OFF ON OFF OFF OFF 8
OFF ON OFF OFF ON 9
OFF ON OFF ON OFF 10
OFF ON OFF ON ON 11
OFF ON ON OFF OFF 12
OFF ON ON OFF ON 13
OFF ON ON ON OFF 14
OFF ON ON ON ON 15
ON OFF OFF OFF OFF 16
ON OFF OFF OFF ON 17
ON OFF OFF ON OFF 18
ON OFF OFF ON ON 19
ON OFF ON OFF OFF 20
ON OFF ON OFF ON 21
ON OFF ON ON OFF 22
ON OFF ON ON ON 23
ON ON OFF OFF OFF 24
ON ON OFF OFF ON 25
ON ON OFF ON OFF 26
ON ON OFF ON ON 27
ON ON ON OFF OFF 28
ON ON ON OFF ON 29
ON ON ON ON OFF 30
ON ON ON ON ON 31

BEL DIGITAL AUDIO BMA2-4SHD Configuration
2006 BEL (Digital Audio) Ltd 16 Version 0.8
Inserting bargraph graticules
The following bargraph scale graticules are supplied with each BMA2-4SHD:
BMA2-4SHD scale graticules
To apply a graticule proceed as follows:
•peel back the protective backing from the chosen graticule
•apply the graticule to the space between a pair of bargraphs
•repeat the process for the other bargraph graticule position
•ensure that the bargraph setting matches the graticule
•adjust the color transitions and peak hold decay as desired