BSS Audio FDS 360, User Manual

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Glossary
24.0 Glossary
Amplitude Refers to the voltage level or intensity of a signal, and is usually measured in
voltage or decibels.
Active electronic circuits are those which are capable of voltage and power
gain by using transistors and integrated circuits. Passive circuits are those
which use only capacitors, resistors, transformers, etc. Active
Breathing
A term used to describe the fluctuations of background noise resulting from
the compressor action.
Attack Time The amount of time taken for the compressor or limiter to start gain reduction
once the input signal has exceeded the threshold level. This is usually
measured in micro or milliseconds (millionths or thousandths of a second).
Balanced A three wire connection in which two of the wires carry the signal
information, and the third acts as a shield tied to chassis ground. The two
signal lines are of opposite polarity at any given moment in time, and are of
equal potential with respect to ground. Balanced connections are used to
improve hum and noise rejection in system interconnections.
Compressor An electronic circuit which reduces its input to output gain as the input signal
increases above a predetermined threshold level.
dB A unit for expressing the ration between two signal levels for comparison
purposes. On its own it has no absolute level meaning. Rather, it is a
logarithmic ration used to express the
differences between two amounts or
levels. Positive numbers indicate an increase, and negative ones a decrease.
Some useful ratios are:
+3dB = Double Power
+6dB = x 2 Voltage or x 4 Power
+10dB = x 3 Voltage or x 10 Power
+20dB = x 10 Voltage or x 100 Power.
dBm The addition of 'm' after dB indicates an absolute scaling for the dB ratio.
Instead of a ratio, the dB becomes a measure of voltage. 0dBm = a power
level of 1 milliwatt into a load of 600 ohms. It is also loosely used to describe
signal voltage in 600 ohm circuits.
dBu or dBv The addition of 'u' or 'v' after dB indicates an absolute scaling for the dB
ratio. 0dBu (or 0 dBv) = 778mV or 0.778 Volts, and it has no regard for power
or impedance. This term is widely used for expressing signal voltages in
modern audio equipment with high input impedances and low output
impedances.
The same scale as for dBu as before, except that 0dBV = 1.0 Volts. dBV