Smack provides side-chain processing capabilities. Compressors typically use the detected amplitude of their input signal to cause gain reduction. This split-off signal is called the side-chain. However, an external signal (referred to as the Key Input) can be used to trigger compression.A typical use for external side-chain processing is to control the dynamics of one audio signal using the dynamics of another signal. For example, you could use a lead vocal track to duck the level of a background vocal track so that the background vocals do not interfere with the lead vocals.
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RTAS plug-ins do not provide side-chain processing when used on TDM-based systems. If you want to use side-chain processing, use the TDM versions of plug-ins on TDM-based systems.
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The Side-Chain EQ filter lets you tailor the equalization of the side-chain signal so that the compression becomes frequency-sensitive. See Smack! Side-Chain EQ Filter for more information.To use an external Key Input to trigger compression:1 Insert Smack! on a track you want to compress using external side-chain processing.2 On the audio track or Auxiliary Input that you want to specify as the Key Input (the signal that will be used to trigger compression), click the Send button and select the bus path to the track that will use side-chain processing.
3 In the track that you are compressing, click the instance of Smack! in the Inserts pop-up menu.4 In the Smack! plug-in window, click the Key Input menu, and select the input or bus path that you have designated as the Key Input.5 Begin playback. Smack! uses the input or bus that you selected as a Key Input to trigger its effect.6 To fine-tune the amount of compression, adjust the send level from the Key Input track.
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When you are using a Key Input to trigger compression, the Input control has no effect on the amount of compression.7 To tailor the side-chain signal so that the detector is frequency-sensitive, use the Side-Chain EQ filter (see Smack! Side-Chain EQ Filter for more information).