Compression is a useful tool for audio editing. It adjusts the volume levels of certain sections of your audio recording; often, compression is used to highlight quieter parts and limit louder parts. In Sony Acid Pro, you can access compression either natively or through external Virtual Studio Technology plugins. External VST plugins can expand your compression options in Acid Pro.
At its core, compression consists of two important parameters: threshold and gain. The threshold control specifies a decibel level beyond which the compression effect will take place. The gain control specifies a decibel boost to the overall compressed signal. Once these parameters have been set, the sections of the audio signal that exceed the threshold will be made quieter. The overall effect is that quieter parts of a song become louder, and louder parts become quieter; the entire dynamic range of the song is lessened, or compressed. Most compression utilities allow you to control other parameters, such as the time delay before the effect takes place and the decibel ratio by which the louder segments are compressed.
VST plugins are external files that can be used in almost any digital audio workstation. These plugins emulate instruments and effects that may otherwise be unavailable in a specific DAW. Most VST plugins have a visual interface that exists in a separate window from the DAW. On this interface, you can control the parameters of your plugin. From within the DAW, you can control the extent to which the plugin takes effect and the specific audio pathways in which it is employed.
Using Compression Within Sony Acid Pro
In order to use compression on your track, click the Track FX button on your selected track. This will allow you to apply a plugin to the track. The built-in compressor plugin in Acid Pro is also called Wave Hammer. If you wish to use an external plugin, select the Plug-in Manager from the View drop-down menu. Select "Configure VST" in the upper right-hand corner. Make sure the folder in which your compressor is located is included in the list. This is the list of folders that Acid Pro will scan for available plugin files. Once your compressor is activated on your track, experiment with the controls until you get the sound you desire.
One common application of compression is a process called side chaining. This involves using a different audio signal to activate the effect. For example, you could side chain a kick drum to the compression on a synthesizer. Whenever the kick drum reached a certain level, the synthesizer would become compressed. In Acid Pro, this can be accomplished by creating two different audio buses, which control the routing of tracks. In the project window, click the "Insert Bus" button twice. Into your first bus, send the input from the track you wish to activate the compression. Select the output of that bus to go to the track you want compressed. Into the second bus, send the input from the track you want compressed. Select the output of that bus to go to the mixer. Place your compressor in this bus. If you find this bus routing daunting, some compressor plugins have built-in controls for side chaining.
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