Processor Types 167
Processor Types
Dynamics processors are generally used to correct or control signal levels, although they can also be used creatively to shape a sound’s volume envelope. The following sections explain the COMP, GATE, DUCKING, EXPAND,
COMP
The COMP processor is a compressor that |
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attenuates signals above a specified threshold, |
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providing automatic level control. Vocalists |
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| Compression ratio = 2:1 |
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that tend to move toward and away from the |
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microphone while singing produce fluctuat- | (dB) |
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ing signal levels; sometimes loud, sometimes |
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Level |
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soft. Likewise, acoustic instruments with a |
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| Knee = hard |
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Output |
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large dynamic range produce sound levels |
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from pianissimo (very soft) through to fortis- |
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simo (very loud). In these situations, it is |
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often difficult to set an average fader level that |
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will allow a voice or instrument to be heard |
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| 0 | +10 | +20 |
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clearly throughout a song or piece of music. |
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| Input Level (dB) |
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This is where the compressor comes in with
automatic level control. By automatically reducing high levels, thus effectively reducing the dynamic range, the compressor makes it much easier to control signals and set appropriate fader levels. Reducing the dynamic range also means that recording levels can be set higher, therefore improving
The COMP processor can also be used as a limiter, which is essentially a compressor with a high ratio setting. Compression ratios above 10:1 are considered to limit signals rather than compress them. When an input signal exceeds the specified threshold level, its level is automatically reduced to the threshold level. This means that the limiter’s output level never actually exceeds the threshold level. Limiters are often used to prevent signals from overloading amplifiers and tape recorders. A limiter with a relatively high threshold, for example, could be used with the stereo outputs to prevent amplifier and speaker overload.
Output Level (dB)
+20
+10
0
Compression ratio = 20:1
Threshold =
Knee = hard
Input Level (dB)
Parameter | Range | |
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THRESHOLD | ||
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OUT GAIN | 0.0 dB to +18.0 dB (0.5 dB steps) | |
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KNEE | hard, 1, 2, 3, 4, 5 | |
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ATTACK | ||
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RELEASE | 5 | |
6 | ||
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RATIO | 1:1, 1.1:1, 1.3:1, 1.5:1, 1.7:1, 2:1, 2.5:1, 3:1, 3.5:1, 4:1, 5:1, 6:1, 8:1, | |
10:1, 20:1, ∞:1 (16 steps) | ||
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