Compression and EQ

1. Another name for a dynamic processor.
2. It evens out the audio volume.
3. The sound is processed and peaks can be removed.
4. Dynamic levels are controlled to prevent the audio from distorting or peaking.
5. Used to prevent quieter instruments from fading out and the louder instruments drowning out others and causing distortion.
6. Limiting
   1. Acts as a more extreme compressor.
   2. Designed to reduce the signal in specific cases to prevent it from damaging equipment.
   3. Short attack.
   4. Ratio close to infinity:1
   5. Hard knee
   6. Can be used with a compressor to clip out the loudest peaks
7. Multi-band compression
   1. Targets specific frequency ranges.
   2. Tries to avoid a "pumping" effect when compressing a mix.
   3. E.g: used to prevent one drum triggering the entire kit's compression.
8. De-essing
   1. "sss", "ch" and "t" sounds can be over-emphasised
   2. Controlled via multi-band compression or a pop shield.
   3. Targets 5-10kHz range.
      1. Sounds are enhanced by EQ and fed into the side-chain input of the compressor , causing it to be more sensitive to these frequencies.
9. Expanders
   1. Reduce signal levels that fall below threshold
   2. Expands dynamic range of a piece.
   3. Most commonly used to reduce background noise.
10. Noise gates
    1. An extreme form of expander.
    2. Uses a ratio closely set to infinity:1.
    3. Can also be used creatively by feeding a drum track through the sidechain.
       1. Can make a synth more rhythmic.
    4. The gate is either open to let a signal through or closed to kept it from sounding at all (or significantly reducing it)
    5. Can have a hold time
    6. Can be used to separate instruments and for live performances where other electrical equipment may cause interference
    7. Range control reduces the sound level below the threshold, rather than to cut it off completely. Creates a more natural sound.
11. Parameters
    1. Threshold has to be set up. When the signal level hits the set amplitude, the peaks are reduced according to the ratio used.
    2. Threshold - the amplitude level above which compression begins.
    3. Ratio - the amount by which the input signal is reduced past the threshold.
       1. How much the signal is attenuated by once it exceeds the threshold. Visually it affects the bend.
    4. Attack time - how long the compressor takes to act after the threshold is exceeded
    5. Make-up gain - the amount you boost the whole mix by afterwards to compensate for compression (lost/cut amplitudes)
    6. Release - how long the compressor takes to stop acting once the signal is below the threshold
    7. Knee - makes the transition less abrupt
    8. Input gain - adjusts the level of input to the compressor. This is important for avoiding distortion.
    9. Stereo link - this links 2 mono compressors. IT's particularly useful if the same settings are required for L and R channels otherwise the stereo image could drift around.
    10. Peak/RMS - peak mode is for catching fast, transient peaks and is more accurate than the levelling mode of RMS, which is based on averaging.
12. Resultant signal is boosted
13. Squeezing the dynamic range by reducing signal level above a user-defined level by a certain amount.
14. Dynamic range - the difference between the highest and lowest amplitude in a piece

Anexos:

• EQ

1. The process of amplifying, filtering or attenuating (opposite of amplifying) audio signal frequencies.
2. Used to enhance perhaps the treble quality of a voice or increase the bass.
3. Stereos have simple EQ controls.

1. When you link 2 tracks so the compression peaks in one track and activates compression on another track
2. E.g: pumping sound in dance music
3. A copy of the input signal is fed to a side chain, which is monitored by the compressor.
4. It's possible to filter the tone so that the processors is more or less sensitive to different frequencies.