by Greg Silsby
One of the questions often heard from newer users of consoles concerns the uses for the mixers Insert jack. This is one of those features that often goes unnoticed until the exploring technician begins to become curious about the few knobs, jacks and doo-hinkies that havent yet been employed.
The Insert adds flexibility. You may, in effect, customize any input channel that has an Insert. While each of your mixing consoles channels probably offers a variety of control features, the nature of the signal coming into the channel may call for some sort of outboard processor to enhance it, tame it, or otherwise beat it into submission. The Insert provides a point within the channel at which you may "break" the signal path and "insert" a signal processor. Some examples include compressors, parametric equalizers and gates. These are all considered "serial" signal processors, as they are wired in series with the channel signal path. That is, the channels entire signal is re-routed through them and returned to the channel. This differs from "parallel" processors, such as reverberation devices (reverbs), which receive a split of the channels signal (or that of several channels) from an Aux Send, and return it to the consoles Master section where it is added back into the overall mix.
Typically found very near each of your mixers microphone and line inputs, an Insert is actually both an input and an output, usually a single 3-conductor, or "TRS" (Tip-Ring-Sleeve), jack. When a TRS plug is inserted, it interrupts the signal path just after the point at which the microphone signal has been brought to line level by the channels pre-amp. Normally, the Tip of the jack is the channel output (+), the Ring is the input (+) and the Sleeve is the common ground for the two. A "Y" adapter, made up of one TRS plug wired to two TS plugs, brings the signal out to the signal processor and returns the processed signal to the channel.
A compressor in this "processing loop" may be just what you need to limit the dynamic range of the pastors voice for recording onto cassette tape. Or maybe youd like to add a more flexible EQ (equalizer) to the channel to reduce the risk of feedback from a lapel microphone. The Insert just may turn out to be one of those features you become very glad you finally discovered.
Greg Silsby is the Commercial Sound & Broadcast Guy, Mackie Designs, Inc. His e-mail address is: Gregs@mackie.com.