BEL DIGITAL AUDIO
BM-A1-S
Introduction
2004 BEL (Digital Audio) Ltd
2
Version 0.3
The BEL Digital BM-A1-S
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 the serial digital video input is selected, the sampling clock recovered from this is
used instead.
The SDI input is used to provide a composite video signal for local monitoring.
The audio source switch selects which audio source is available to the speaker selectors, the
bargaphs and the analogue audio monitor line-out connectors.
The left and right speaker switches select which of the currently selected 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 applied with the balance and volume knobs providing control voltages. Soft
limiters are used to protect the speakers. The headphone output, which is taken before the
limiters, mutes the speakers when used. Alarm tone is added just before the speaker output.
When select switches are used a soft mute is applied to the audio to reduce glitches.
