Sony SRP-X700P - Manual (Page 40)

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10. Glossary
(Tentative)
AD (Analog to Digital)
Converting analog signal (continuous variation in current or voltage) to digital word
(represented by binary number).
In SRP-X700P, 48 kHz sampling frequency and 24 bits quantization are incorporated.
Automatic Mixing
It is a function to provide automatic sound volume control.
In SRP-X700P, it contains such as input compressor, input gate and output limiter, and is
available in microphone sources.
N.O.M (Number Of Microphone)
This function suppresses feedback by automatically reducing the microphone input
level by 3 dB whenever the number of open gate of input is double.
Last On
It keeps open the gate of microphone input channel that feeds the sound last of all.
Only One
It restricts the number of microphones that can be used at a time to only one
channel. It is enabled by opening the gate of only the channel that first feeds the
input signal.
Balanced
A type for input and output interface. Signals of in-phase (called ‘hot’) and out-of-phase
(called ‘cold’) are consisted as well as ground. It is called differential- mode being equal
level but opposite polar. And the signals become common- mode being same polarity at
input. Noises picked up in interconnection between output device and input device are
cancelled at the input.
A balance line includes three wires of the hot, cold and ground often surrounded by a
shield. Advantage of balanced connection is to reduce the picked up noises.
For long distance interconnection of audio devices and microphone connection, the
balanced connection is popular.
Compressor
It is to control audio level. When input signal exceeds a pre-specified level (threshold
level), the gain is reduced by the compressor. Dynamic range of a program is reduced.
The compressor is set up with Threshold Level, Compression Ratio (slope), Attack Time
and Release Time. Threshold Level settles level in which compressor operation is
initiated. The compression ratio settles ratio of signal dynamic range between input and
output of compressor above the threshold level. The attack time settles time between the
signal exceeding above threshold level and the compressor initiation (usually for the gain
to decrease by 63% of its final value). The release time settles time between the signal
falling below threshold level and the stop compressing (usually for the gain to return by
63% of its original value)
.
For example, it is used to avoid excessive output level to protect a speaker unit, to provide
a certain mixed output level for microphone sources, to take the same output levels of L
and R, etc.