STEREO DELAYShort delays of only a few milliseconds will alter the apparent position of an instrument. Using a stereo delay of no more than 5 milliseconds, try adjusting the level of the undelayed side in order to relocate the perceived position of the signal without causing any separation between the original signal and the effect. This will allow you to create a space for the instrument without the need for hard panning, by utilizing what the ear perceives as a sort of virtual third dimension along the horizontal stereo plane. Another way of achieving this effect is to convert an instrument track to mono, bounce it in place and then duplicate it. Then nudge the duplicate track forward or back by a few milliseconds, until you have found a spot in the soundstage that suits your needs.
POLARITYAnother technique used to make an existing stereo signal appear wider is to take a little of the left channel, reverse the polarity and mix it into the right channel, and then do the same for the right channel. Start by duplicating your stereo track, then pan one track hard left and the other hard right. Next, flip the polarity of one of the tracks by 180 degrees. Then adjust the fader levels on both tracks until you achieve the desired widening effect. Keep in mind if you push the volume balance between the two tracks too far you will end up with an undesirable hole in the middle. Also be sure to check everything in mono afterwards to make sure it translates.
REVERBAdding a delayed reverb to a sound signal can provide more natural sounding ambience. Simply pan the original track a minimum of 45 degrees to one side, add a short delay of around 5-8ms and pan that to the opposite side, then add a barely audible amount of reverb to the delayed signal. By doing this, your signal will become more natural-sounding by adding a what the ear perceives as a slight reflection. You could also add some stereo reverb instead, and the result will be slightly brighter. Experimenting with reverb on panned elements can add an interesting depth and ambience, especially to sounds with slower attack and release such as strings and pads.
MID/SIDE PROCESSINGMid/Side processing is an advanced technique that allows for subtle and creative changes to the stereo image of your audio tracks. It works by decoding a stereo signal into two components, a “mid” channel that contains just the information that appears in both the left and right channels, and a “side” channel that contains all the difference between the left and right channels. Once encoded into M/S, these two signals can be processed separately, before being converted back into conventional Left/Right stereo signal. The easiest way to adjust width using Mid/Side processing is to either give the Side channel a boost, or lower the Mid channel. If you boost the mid channel relative the side, you will narrow the stereo width.
Using Mid/Side processing you can adjust the width somewhat selectively using a Mid/Side capable EQ. Most modern EQ software plugins have a feature that will allow for Mid/Side processing. Keep in mind that whenever you use Mid/Side EQ, you are adjusting the ratio of the sum and difference information in your mix, in the area you are processing. Thus boosting the upper midrange in the Mid Channel might improve the clarity of vocals, however this will reduce the stereo width in that range as well.
While EQ is probably the most common device used for Mid/Side processing, there are other ways to separate and process the different parts of a stereo signal. Compression, transient shaping and imaging tools can also allow for the dynamic balance of the mono and stereo signals to be adjusted, allowing for varying degrees of depth and width in the stereo image.