There are basically two ways that processors and effects are usually connected to a mixer. This is because there are basically two types of processor - 1/ signal controlling processors, 2/ signal enhancing processors.
The first group, signal controllers, are basically correction tools. Some of the things in this group are 1/ Compressors, 2/ Noise gates, 3/Equalizers, 4/De-essers.
The second group, signal enhancers, contains things like 1/ Reverb, 2/ Delay or Echo, 3/ Chorus, 4/ Flange etc.
Because the first group is used to correct problems with the sound they are usually connected to the problematic channels insert point, this is because the insert INTERRUPTS the signal, only letting you hear the output or corrected sound, you dont want to hear the original signal if it has problems.
The second group are used to add colour and shape to the sound of a mix and can be used on more than one instument at the same time, you dont need to interrupt the original signal, only to add a little extra to it. These are usually connected to the mixers (Post Fader) Auxillary sends, with the channels 'aux' used to set how much of each effect is added to each channel.
There are two types of stereo effects units, the first will probably only be referred to as 'stereo' in the manual, whereas the second should be identified as 'True Stereo' or 'Dual mono'.
The first type, even if it has two input jacks, actually uses a mono input signal, it then splits and processes the split signal slightly differently for each channel, producing an artificial stereo output. Many of the older effects units are of this type.
The second type actually has two completely independent channels which are processed seperately, whatever is input to the left channel comes out the left output only. Sometimes the two channels can be used for completely different things.
With the first type you only need to use one input, so you can connect it to one (post fader) auxillary send, if you want the simulated stereo output you connect both outputs either to the corresponding stereo auxillary return, or if you want to be able to EQ the signal, to a stereo channel line in (or two mono channels).
For true stereo /Dual mono units you will need to connect one channel to one aux send and the second to a seperate one (aux 1 & 2 or 5 & 6 etc). You can return the outputs to the board in the same way.
An unbalanced cable is a two connector cable, one 'hot' one 'ground', like a guitar cable. Balanced refers to the way the connectors are hooked up rather than the type of cable, eg. 1/4 and RCA are both unbalanced cables.
A balanced cable uses three connectors, and is designed to reduce noise that might be picked up in long cable runs or bad enviroments. Basically the 'hot' signal is duplicated, then sent down the third connector with the signal waveform inverted, where there is a peak on the hot there is an exactly opposite valley on the other line. Now here's the magic part, any noise that is picked up by the cable will be the same on both the 'hot' or 'high' and the inverse or 'low' cables, so when the signal arrives at its destination the piece of equipment receiving the signal flips the 'low' so that it is the same as the 'hot', this means that the noise is now out of phase, the two signals are then added together and the noise cancels itself out! Brilliant!
