Behringer MDX2200 user manual Applications, Compression/levelling/limiting/clipping

COMPOSER PRO MDX2200

inaudible as soon as considerably louder sound signals in the same frequency band are added. Nevertheless, the further the level that the desired signal decreases, the more the noise floor becomes a disturbing factor. Expanders or noise-gates offer a solution for this problem: these devices attenuate signals when their ampli- tudes drop, thereby fading out the background noise. Relying on this method, gain controlling amplifiers, like expanders, can extend the dynamic range of a signal and are therefore the opposite of a compressor.

In practice, it is shown that an expansion over the entire dynamic range is not desired. With an expansion ratio of 5:1 and a processed dynamic range of 30 dB, an output dynamic range of 150 dB will be the result, exceeding all subsequent signal processors, as well as human hearing. Therefore, the amplitude control is restricted to signals whose levels are below a certain threshold. Signals above this threshold pass through the unit unchanged. Due to the continuous attenuation of the signals below this threshold, this kind of expansion is termed “downward” expansion.

The noise-gate is the simplest form of an expander: in contrast to the expander, which continuously attenuates a signal below the threshold, the noise-gate cuts off the signal abruptly. In most applications this method is not very useful, since the on/off transition is too drastic. The onset of a simple gate function appears very obvious and unnatural. To achieve inaudible processing of the program material, it is necessary to be able to control the signal’s envelope parameters. This is part of the many features of the COMPOSER PRO.

4. APPLICATIONS

In this section, several typical applications of the BEHRINGER COMPOSER PRO are discussed. The follow- ing basic settings can resolve most dynamic problems. They are the ideal starting point. Please take the time to study the application examples carefully, in order to be able to make full use of the COMPOSER PRO’s capabilities in the future.

Main Applications And Initial Settings

The main applications of the COMPOSER PRO can be divided into three categories:

1.The EXPANDER/GATE section is used to eliminate interference and to suppress background noise and leakage on individual tracks in multitrack recording.

2.The COMPRESSOR section is used to compress the program material and to create special effects and unusual sounds, which are used for recording and musical performance.

3.The subsequent PEAK LIMITER section is designed to protect loudspeakers, tape recorders, transmitters etc. from being overloaded.

4.1 Compression/levelling/limiting/clipping

Now that the functions of the individual sections have been clearly explained, we would like to acquaint you with more terms and relationships of the dynamics process.

Compression

A compressor converts a large dynamic level into a restricted range. The extent of the resulting dynamic level is dependent on the threshold, attack, release and ratio settings. As it is the desired effect of a compressor to increase a low level signal, generally the threshold is set low. The “inaudible” compression mode requires fast attack and release times and low ratios. The faster the chosen control times and the higher the compression ratio, the greater the effect on the short term dynamics. This fact is often used to achieve audible and creative sound effects.

Levelling

The levelling mode is used to keep output level constant, i.e. to compensate for long term gain changes, without affecting the short term dynamics. Normally, the threshold is set quite low in order to be able to increase low level signals. Levelling requires slow attack and release times, combined with a high ratio. Be- cause of the very slow response time, levelling has no effect on signal peaks or short term changes in average level.

Limiting

The limiting function requires a fast attack time and a high ratio and release time setting, which is dependent on the specific use and the desired sound effect. As it is usually the task of a limiter to limit only high signal peaks, the threshold is usually set at a high level. The dynamics are reduced dependent on the ratio setting and the degree by which the threshold point was exceeded. If the attack time is adjusted to control only the

4. APPLICATIONS 15