What is an insert point?

My audio interface has what's called an 'insert point'. What is it? What can I do with it?

So asks an Audio Masterclass website visitor.

You can also find insert points in the channels of mixing consoles, and in the virtual channel strips of digital audio workstation softwares.

Here we will consider physical rather than virtual insert points.

An insert point allows you to break into the path of an audio signal and connect a signal processor of some kind into that path.

So in a mixing console, typically the signal flow would be from the microphone preamplifier to the equalizer, to the auxiliary send section, to the pan control, to the fader...

• Microphone preamplifier
• Equalizer
• Auxiliary send section
• Pan
• Fader

The insert point would normally be between the microphone preamplifier and the equalizer. So you could insert, say, a compressor to even out the dynamic range of the signal.

One important point to note is that the whole of the signal is processed. None of the direct signal is passed on; only the processed signal gets through.

Insert points are commonly presented as a single jack socket (per channel).

This will be a so-called TRS (tip-ring-sleeve) jack with three contacts. One contact will send the signal from the microphone preamplifier to the inserted device. Another contact will return the processed signal from the inserted device back to the channel. The other contact is ground.

There is no defined standard to specify whether the tip contact should be the send and the ring contact the return, or vice versa. You'll have to look at the manual.

To use an insert point such as this, you will need a special insert cable. This typically will have a 3-terminal jack connector at one end, which is exactly the same connector as a full-size stereo headphone jack. From this, two cables will emerge which end in 2-terminal jacks, which are exactly the same as guitar jacks.

The 3-terminal jack goes into the insert point, the other two to the input and output of the connected equipment. Take care to get them the right way round.

One important point to note is that this cable will look very similar to a Y-splitter cable. However, the Y-splitter will normally have three jacks all of the same type - 2-terminal or 3-terminal.

You don't have to switch in the insert point. It will be activated automatically when you insert a jack into the insert socket.