We are here today to demystify the channel insert functionality of your audio mixing console. Think of an insert as a signal detour. The insert serves simultaneously as both an input and an output for either a single channel or for some other signal path, such as a submix or main output bus. On a digital console, it is typically accomplished internally in the virtual portion of the audio console. It is a point in the signal path at which the signal can be sent out of the channel or mix and then returned to its signal path at the same point it left, creating a signal loop. In other words, it allows you to “insert” an outboard (external) or virtual (internal or digital) device into the signal path. On most analog mixers, a single ¼” three-conductor jack provides connections for both an input and an output. Most digital mixers must be routed to a physical analog jack on the back of the audio console or to a digital external device like a computer or effects rack like the Waves SoundGrid.
Typical Uses for Inserts in Your Workflow
Apply Effects to a Channel or Mix
Since an insert is both an input and an output, you can route the signal from the channel out to a reverb, compressor, limiter, etc., and then back into the channel. You might send the signal to a noise gate to automatically “turn off” a mic when it's not in use. Reducing the number of mics that are on, or “open”, reduces the risk of feedback sound and improves your signal-to-noise ratio.
Use it as a Direct Output
Like a post-mic preamp (head amp), but pre low-cut or hi-cut filter, mute, EQ, fader, etc. Just because you're sending something out doesn't mean you have to bring it back. You can use each insert to send a “direct out” signal to a line-level input of a recording device, or to another mixer for a broadcast or recording feed. This can be done at the mixer end of your direct out cable, you'll want a standard 1/4" mono (or TS, tip/sleeve) phone plug. Push the phone plug part into the insert jack, just to the first click. This will route the direct out signal via the cable, without interrupting the signal flow in the mixer. On an analog mixer if you insert the plug all the way to the second click in the insert jack, you will still get a direct out signal, but the signal in the channel will be interrupted at that point — removed from the mix.
Send a signal through a “Y”
This is done using the insert as both a direct out and an effects loop. As an alternate approach, create your effects loop as described earlier, then insert a “Y” adapter after the processor to affect (compress, for example) both the direct out and the individual channel in the mix. A good application for this might be to compress a lapel mic or a pulpit mic, in both the house mix and a recording or broadcast. On a digital mixer you may be able to route the insert point out digitally to other points in the mixer or through the network (like Dante, AVB, S-link, or AES 50).
Whether you are using inserts as part of your normal setup every week, or just to solve an occasional routing problem, they add tremendously to the versatility of your audio mixing console.