Mid-Side Technique

I experimented with the Mid-side technique in lectures today.
This technique can be used for many different applications from Drum overheads to acoustic guitars.


The technique involves using two mics, each with separate polar patterns. One set to Cardioid and the other to figure of 8.


We set up two SE Titans on mic stands as overheads for a drum kit.
The mics were set up in the way that the microphones were about 2-3m away from the kick drum and were pointing vertically one on top of each other.


The top mic was placed facing downwards directly over the bottom mic but not touching. The top microphone was set to the cardioid polar pattern and was facing the source.
The bottom microphone was set to the figure of 8 polar pattern and the pickup areas were perpendicular to the cardioid pickup area. An example of this is shown in the link: Click Here.


This creates a stereo feel to the mix but this can only truly obtained once it has been processed.
This is because, in order to obtain 'stereo' imaging, you need to be able to have a left an a right channel.
There are several ways to process the signal in order for this to happen - these include - digital processes and re-routing the signal back through the desk in a similar fashion to the digital option.
More than one digital option is available to use: track duplication (which is the process that we used and that i will explain) or the use of a plugin which does this for you. It is completely to your preference and there is no set way - everyone has their own way of working.


In order to obtain the stereo image, you have to duplicate the track in the Digital Audio Workstation (DAW) (such as Logic or Pro tools). The microphone track that had the figure of 8 polar pattern is duplicated so you had two identical channels. After two of them are present, you need to open up a plugin in either one of the channels (doesn't matter which) that allows phase inversion to occur. In Logic, this option is available in the 'Gain' plugin. Once the phase has been inverted, you notice a difference in sound - this is due to phase cancellation. In order to resolve this, you need to pan the tracks hard left and hard right. This eliminates phase issues and mix is back to the sound that you are aiming to get.
Once the two tracks have been panned, the process is almost over. 
There is one final stage and that is bringing back the cardioid signal and blending it with the other tracks. This is all down to preference and taste - depending on how much room sound you want in relation to the source sound.


The drums sounded really full and defiantly benefitted from the technique.
It can take a while to get used to but it brings out a wider perception of the instrument at hand.


We used this process and compared it to the original two microphones before hand and there is a big difference! I would highly recommend experimenting with this technique!