This can be fed from an instrument directly, fed a copy via a Spider Splitter, or fed an auxiliary send from the main mixer for flexibility. Reason’s MClass compressor simply has a mono sidechain input alongside its inputs and outputs. How you go about setting up sidechaining will vary depending on what DAW you’re using, so let’s look quickly at the most popular DAWs and see how the process is handled in each. Audio example 01 on the DVD demonstrates this with the compression initially turned off and then with it on. The two main differences are that the processed signal at the compressor’s input is a pad sound, and that the compression release time is carefully set for a musically pleasing rise time of the pad volume after gain reduction, before the next bass drum pushes its volume back down again. Using very low attack and a low-to-medium release value will make the dip in volume so fast that it is almost unnoticeable.įeeding a copy of a bass drum to the key input of other sounds being compressed is responsible for the famous rhythmic pumping effect used on Call On Me by Eric Prydz. The parameters for this are the same as normal compression, with threshold and ratio dictating how severe the gain reduction is. This pulls down the bass line volume when the bass drum plays, which enables you to have consistent bass energy without the usual volume bump as two bass-orientated sounds play at the same time. Classic uses of this setup include compressing a bass line when a bass drum plays by feeding the compressor that processes the bass line with a copy of the bass drum as its key input. This enables you to feed any external audio signal you want to the key input, so that it’s a different signal controlling the amount of gain reduction from the signal present at the processing input. It’s external sidechaining that is responsible for the popular effect heard on so many records today. This section is called the sidechain, which is technically correct – but it’s an internal sidechain, not an external one. This lets you choose which rhythmic element makes the compression kick in, or pump, rather than reacting to all elements present in the signal.
For instance: by filtering the key signal with a low-pass, you can focus on just the bass drum of a busy drum mix, which in turn will eliminate gain reduction being triggered from other sounds in the signal (like the snare drum, for example).
This is designed to make the gain detection react to the dynamics of specific frequency areas of an audio signal. This section listens to the key signal, then applies gain reduction to the main signal passing from the input to the output.Ī common point of confusion is the inclusion of filters for this internal sidechain section on some plug-ins. The other copy is sent as the internal sidechain – or key input – which goes into the gain detection section. One copy passes through to the output with the desired gain reduction applied to it. When using a sidechained compressor, the signal you want to process at the input section is split into two.