This article gives information about various ways to use Sidechains in the Modular Mixer

Sidechaining is used to modulate the gain of a sound source, thanks to another sound source.

Generally, Sidechaining is explained to be done with dynamic effects such as compressors, to create a pumping effect. The classic example is to modulate a bass with a kick drum, in order to modify the way the bass attack sounds according to the various parameters of the compressor such as the ratio as well as attack and release parameters.

But this is a trick when you think that the resulting effect is simply a level modulation, where the level will follow the shape of a modulator which could be any sound source you think about. Taking this approach can give a wider range of effect than classic sidechaining, and c an be used to create gate sequences or soft compression.

1. Standard Scope Sidechains

In Scope, the standard way to use sidechains, is to load a compressor and use its "SC" function to select amongst various sound sources the one to use to modulate the levels of the sound.

It is just a matter of the compressor in question having or not this "sidechain" module. Most Scope 5 effects have it, and it can be found on compressors such as Vinco and others.

The picture below shows the sidechainer menu in Vinco: it accessible by right-clicking on the left or right SC source displays. Here, I have selected LFO B of the "3LFOs" to modulate Vinco copressors.

2. Modular Mixer's Sidechainers.

Using sidechainer is like using a device specific to do sidechaining. The advanatge is that the modulators are made to allow a great variety of level effects, and having a standalone device allows to concentrate on making the right functions to reach different results than standard sidechaining.

Sidechainers come in 3 versions with 24, 16 or 8 channels.

The interest of having many channels is to be able to select a modulation amongst a great variety of channels, if not all outputs of his audio-sequencer.
Having fewer channels allows to save dsp by using smaller devices. In that case, the user will route in his audio-sequencer, the correct outputs to feed to the sidechainer.

Also, having smaller devices allow to make cleaner projects by using smaller modules in between other small ones.

The following picture shows the sidechainers colored in dark-blue. They are generally input devices, connected before the channel or stems. Here, using a big SC24 allows to to sidechaining entirely in the same device, before feeding the mixing network.
Notice the second module, between Stem247 and MB7: the SC82 allows a clean connection before MB7. It could have also been used to a have a few sidechainers before channels, and others after the channels.
Notice also how I connected the 4 mono preamps from the "ADAT A" source (same source connected to both Left and Right inputs), because all sidechannels are stereo.

(this picture is not an actual Scope or Xite project, but is taken in SDK and colored to show where to connect SC devices).

using a microphone as a source modulation for sidechain is easily done by connecting it to the SC1 or 2

Here is an actual project in Scope 4.5, which uses the SC162 (16 channels) which is enough to have sidechain everywhere it is really useful:
- 12 stereo asio channels + 4 external stereo synths feed the SC162 and a 16 channel module.
- the additional 4 mono preamps are not connected to the Sidechainer, because they are mics and instruments not used as sidechainer at recording stage...

It translates as a 20 channel mixer (16 stereo + 4 mono) with 6 aux... and where 4 channels are still free to use or to switch off DSP.
It looks like the pic below, with a 1920*1200 screen resolution : 20 channels at the top (colors were imported from the stems), and a view on all modules of the mixing network.
20 channels is the maximum viewable confortably at such resolutions. Of course, one could put channel modules under each other and easily see large numbers of channels... or use two monitors.