Adjusting Digital Input Gain - AMX BCS Instruction Manual

Adjusting and Verifying Audio

Adjusting Digital Input Gain

For BCS purposes, adjustments to input signals are referred to as digital gain adjustments, while similar
adjustments to output signals are referred to as volume adjustments. Not all systems with audio support
digital input gain adjustments. Although digital input gain is normally set during installation, if your
system supports digital input gain control, gain adjustments can be made at any time during normal
operation. Digital input gain range is -10 dB to +10 dB. Inputs cannot be muted.
Digital input gain should be adjusted as part of system setup. If adjusting input gain, we recommend
doing so before making any output adjustments.
Caution: We strongly recommend that input gain adjustments be made only by a qualified installer
or dealer.
The purpose of controlling the input gain (the nominal level of the signal from the source device) is to
allow source signals of various amplitudes to be equalized before they are routed and the volume is
adjusted. Equalizing source levels provides a consistent reference for volume adjustments and eliminates
jumps when routing a new input to an output.
Typical uses for input gain include switching consumer and professional grade audio equipment (whose
levels can vary noticeably) in the same routing system. Input gain adjustment is also used for equalizing
amplitudes between balanced and unbalanced inputs.
Note: The total through-system gain (the amount of input gain plus the amount of output gain) for
any input to output routing path is automatically limited by the matrix switcher. (For the value of
through-system gain and other audio specifications, see your matrix switcher's instruction manual.)
If a volume command is entered that exceeds the matrix switcher's specifications, the command will
be accepted (and will be indicated in status results) but will not result in an audible difference if the
dB value entered is outside of the matrix switcher's audio range.
The following section describes three methods used to adjust digital input gain as part of the process of
equalizing input levels. We recommend routing an input before adjusting its gain; although not
necessary, it can be helpful to hear the adjustment.
To adjust digital input gain use any of the following three methods:



Important: If the level is not specified in a BCS command, the command is executed on the default
level (normally Level 0), which is defined in the configuration file. If the level is omitted and the BCS
command executes on an unexpected level, check the default level in the configuration file
(for systems without a configuration file, check the product documentation).
To adjust inputs to equalize source levels:
1.
Route an input (source) to the first output (destination).
2.
Adjust the digital input gain for the input to the desired dB level by using one of the three methods
on the following two pages.
3.
Repeat Steps 1 and 2 for additional inputs that will be routed to the same output.
16
Absolute – adjusts input gain to a specific decibel value
Relative – adjusts input gain by a specific decibel amount
Increment/Decrement – adjusts input gain up or down a step
Instruction Manual – BCS Basic Control Structure Protocol