Nexo NUAR - Manual (Page 48)

MENU DESCRIPTION
With heavy content, like open air rock concert, you will need the full input range sensitivity.
This is the most typical situation. In that case, the headroom should be adjusted to 0 dB.
Analog input
level control
24 Bits
ADCs
Analog A
Analog B
Analog C
Analog D
Digital Signal
Processor
24 Bits
DACs
Analog Outputs
level control
Amp ch1 Input
Amp ch2 Input
Amp ch3 Input
Amp ch4 Input
Default headroom position (0 dB) situation :
Max input level Max Output Level
Example above shows large input attenuation and large output gain. Overall gain is 0 dB (before amplifier).
But in quiet environment, like background music or small acoustic set, you won’t use the
full dynamic of the NXAMP input converter. In that case, you can lower the headroom
value, meaning that the input headroom of the amplifier is reduced; thus improving the
effective resolution used on the analog to digital input converter.
Analog input
level control
24 Bits
ADCs
Analog A
Analog B
Analog C
Analog D
Digital Signal
Processor
24 Bits
DACs
Analog Outputs
level control
Amp ch1 Input
Amp ch2 Input
Amp ch3 Input
Amp ch4 Input
Min headroom position (-8 dB) situation :
Max input level Max Output Level
Example above shows small input attenuation and small output gain. Overall gain is 0 dB (before amplifier).
In the same time, the output (analog or digital) gains of all the channels are automatically
adjusted to keep the same overall gain from inputs to outputs of the NXAMP.
Advantage of reducing the headroom is that it adapts the resolution of the converters to
the scale of the analog input signal, thus improving background noise and reducing
distortion.
Drawback of reducing the headroom is that you may clip the converters before clipping the
amplifier, thus virtually reducing the output power of the amplifier. Thus when adjusting
the headroom, be sure to always use program material that matches the actual program
that will be played, and check that the Peak LED for this channel is not starting to blink at a
lower level than before; it yes, it means that you are lowering the maximum output of the
amplifier because of a too low headroom, then increase the headroom.
Default headroom position (0 B) should be considered for most application. If
you are not sure of how to adjust headroom, leave if to the default position (0
dB) which is the safest position.
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