NewTek TriCaster TC1 (2 RU) - Manual (Page 183)

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C OMPRESSOR L IMITER
The Compressor/Limiter is capable of preventing clipping (see
Section 16.9.1) from unexpected peaks or transients, and making
talent sound better than they do in real life, bringing voices, music
and other audio sources into an optimal dynamic range. Being able
to do this independently for each output too is icing on the cake,
especially for Internet streaming, as it ensures correct levels at any
time.
T HRESHOLD
Sound above the set Threshold level will be compressed; the
amount of compression and the manner in which it is applied are
both dictated by the other settings.
R ATIO
A Ratio of 4:1 means that if input level is 4 dB over the threshold,
the output signal level after compression will be just 1 dB over the
threshold. The gain (level) is reduced by 3dB. Very high ratio
settings are the reason the word “limiter” is pa rt of the title for this
feature.
The highest ratio setting will effectively reduce any signal that
would rise above the threshold all the way down to the threshold
level (with the exception of a brief period during a sudden increase
in source loudness, as dictated by the
Attack setting).
A TTACK
Attack is also in milliseconds. The setting represents the amount of
time it takes for the gain to change by a specified amount.
It would not be grossly incorrect to think of this setting as changing
the slope of a graph depicting how aggressively the compressor
pursues the target value (defined by applying the
Ratio setting to
the amount the signal surpasses the Threshold ). Shorter values are more aggressive, while longer values are
more subtle (and tend to be less noticeable to the audience).
R ELEASE
Release is like Attack in many ways but refers instead to the speed with which the compression effect is
removed as a source signal falls back on its own so that it no longer exceeds the Threshold .
G AIN
Naturally, compression impacts the overall output level of the source or output. The Gain control allows you
to compensate, bringing the post-compressor/limiter signal back to a comfortable nominal range.
Hint: Different circumstances call for different Attack and Release strategies. For example, much less
aggressive settings could work nicely for vocals, but fail badly when applied to a snare drum. Many websites
provide suggestions on establishing the best compressor/limiter settings for different environments.
Compressor … Limiter – what’s
the difference, anyway?
Compression and limiting are
not really different processes,
but rather a matter of degree
and
perceived effect.
Compression, ideally, takes the
form of a subtle, almost
imperceptible modulation of the
sound level to bring it into a
more pleasing and convenient
range. A limiter is applied more
for the purpose of managing,
even
‘ crushing ’ , unwanted
spikes and transients.
That distinction aside, a limiter
is essentially just a compressor
set to a high ratio and, generally,
a fast attack time. Audio
engineers typically consider
‘compression’ with a ratio of
10:1 or more as ‘limiting’.