Antex Electronics SX-5e - Manual (Page 56)

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milliwatt into 600 ohms, which is .775 volts RMS. dBV uses 1 volt
RMS as the reference.
Digital Clipping
Digital clipping is the point where the Analog to Digital converter
becomes saturated. The signal is “all ones”. For a 16 bit system,
this is a value of +32768 or –32768. Digital clipping sounds nas-
tier than analog clipping because of its abruptness. It has no re-
gion where the distortion increases progressively.
Digital Volume Control
A digital volume control is one that scales the signal in the digital
domain by multiplying by a fraction less than one. A volume con-
trol which has a digital interface, such as up and down pushbut-
tons, or a virtual slider on a computer screen, may operate on the
signal in either the analog or digital domain. Only the specifica-
tions of the device will tell you whether the control is actually digi-
tal or analog. The digital type of volume control will degrade sig-
nal to noise performance when used. If a signal is lowered by 6
dB, the signal to noise ratio is also lowered by 6 dB, effectively
removing one bit of resolution. A digital volume control set at –48
dB will effectively turn a PCM16 signal into a PCM8 signal.
Whether or not the decreased signal to noise ratio is acceptable
or not depends on the particular situation.
Headroom
Headroom refers to the amount a signal may be above the nomi-
nal signal before clipping occurs. Increasing headroom lowers the
possibility of clipping on peaks, but degrades signal to noise ratio.
Optimum headroom to have for a particular recording is very
subjective and depends program material. Classical music usu-
ally requires the greatest headroom. Headroom of 12 dB is a
typical number.