The part of the circuitry that monitors the input level is known as the side-chain, and it controls that part of the circuitry that adjusts the gain of the main signal path. While some classic hardware compressors use an alternative system, where the threshold is fixed and the user instead sets the amount of compression by adjusting the input drive level, the outcome is much the same: if the signal rises above the threshold, the compressor or gate responds.

Chain Reactionīoth gates and compressors normally work by monitoring the amplitude or intensity of their own inputs, so that they can detect whether the level is above or below the threshold value chosen by the user. Essentially, they do the same job as their hardware counterparts and this short feature aims to explain exactly what a side-chain is and how external access and filtering may be used. While software plug-in emulations of compressors and gates may include options for external side-chain access, or for filtering the side-chain signal, it seems that many users are ignoring these features because they're not entirely sure what they are for. But what value does this technique have in the modern project studio? With the powerful automation available in modern DAWs, it is easy to overlook their side-chaining features.