Automatic control of audio-signal levels, also known as dynamics processing, started out as a means to prevent levels exceeding available dynamic range - avoiding waveforms becoming clipped - as in a Limiter. It was also developed as a means of controlling the level from a singer's microphone or from an instrument - as in a Compressor.
Today, compressors are combined with limiters, or with Gates, to keep out unwanted noise, and Expanders can be used to bring up the level of quieter signals.
Hit an In button (bottom left of "Oxford education", right) to turn on any of the six available sections. Hit an Access button to display the appropriate controls. These buttons light up to indicate which sections are in use and which set of controls is currently being accessed. The full version incorporates six sections: Gate; Expander; Compressor; Limiter; Side-chain EQ; and Warmth. The two-band side-chain EQ facilitates de-essing and other effects. The neat thing is that this EQ can be inserted into the main signal path - even while still being used in the side-chain. The Warmth section adds loudness, punch and definition to the sound of the dynamics section. It works by increasing the density of higher-value samples within the audio - boosting signal levels without increasing peak levels.
Various versions are provided that exclude certain sections to lighten the load on the processor. For example, the standard version omits the side-chain EQ, so its Access and In buttons are greyed out in this version. The Compressor/Gate, Gate/ Expander and Compressor/Limiter versions also omit the side-chain EQ while including the Compressor and Gate, Gate and Expander, or Compressor and Limiter sections, respectively - and they all include the Warmth section. A special bass-compressor version is also available for 5.1 surround work, again with just Compressor, Limiter and Warmth sections included. In this version a 24dB/octave variable low-pass Sub Filter replaces the side chain EQ to allow automatic generation of a Sub-channel from normal wide-band channels.
Sony has designed a compressor that allows versatile control for both corrective and creative applications while at the same time producing the warmth with digital audio that is normally associated with analogue audio. The user-interface will be useable by recording professionals, but amateurs can afford it.