Using a MS microphone configuration is often a brilliant solution for creating a clear mono component and controllable stereo image. The result is, when done correctly, a mono compatible sound. This is something which is much harder to achieve with other conventional setups like ORTF or XY setups.
Making M/S is typically done with a figure 8 mic and a cardioid mic, like for example a Schoeps CCM8 and Schoeps CMIT5U. This is a good combination because they come from the same brand. That is a big help in offering consistency in your sound. The capsules match closely and when used together they blend easily in your mix.
The MS ‘trick’ is to take in the figure 8 mic on 2 channels on your mixer, put 1 channel out of phase, pan hard left and right and mix them with the monocomponent of the CMIT5U in this case. If you gang the two figure 8 channels, they’ll stay in perfect balance and give you precise control over you stereo width.
No figure 8 mic needed?
So the previous combination is very nice but also hurts your wallet pretty hard. You could, as a quick and dirty solution, use 2 cardioid microphones and place them opposite to each other. Be careful to choose true cardioids and not hypercardioids because of the bigger sensitive area at the back of the mic. Make sure the two mics are of the same brand and type, so they will match as closely as possible. We’ll call the left mic S1 and the right one S2. This set will be your ‘new’ figure 8 S-combo.
In your DAW pan S1 hard left and S2 hard right and gang the 2 mics. Now, this is your new S component. Then setup up your M-mic and mix it with your S-mic.
The result is not a real MS setup, but a good effort to achieve the same effect. But a few things are happening here. First we have level issues, we are simply adding up more mic and thus increasing our level at least 6-12 db. And second, we’re experience a lot of phase issues here. That’s mainly because we do not have a S component which works like a real figure 8. Figure 8 does have a front (+) side and a back (-) side. The S component in this method has 2 front (+) sides opposite each other. There is no back side because we are using the 2 mics as a very wide ORTF (if we could give it that name).
Creating a pseudo figure 8 the ultimate way
Here’s a solution which comes closer to a figure 8 mic. Preferably use 2 cardiod mics which are of the same make and type. Connect your M-mic to channel input 1, this will be your Mono/mitten mic. Connect the 2 opposite LEFT and RIGHT mics to input 2 and 3. These will form the new figure 8 mic.
You can make a figure 8 mic out of 2 cardiods by letting them face each other at exactly 180 degrees. This has to be done fairly precise because this will immediate have an effect on the result. Take a stereobar to construct the two mics on. Connect the mics to you DAW and keep the panning centred.
Take your iPod out, play some music on a loudspeaker and stick it in front of the two mics. Now it’s time to listen on your headphones to the mics on your DAW. Your goal is to create total phase cancellation. Let LEFT be in a steady position. Shift the RIGHT mic in such a position that it totally cancels out the signal. There will be some high frequency spill left, due to physical reasons of the mics. Once you have found the out-of-phase spot, make sure RIGHT is steady as well. They’re now in complete out-of-phase position, the hardest part is over.
Let’s say the LEFT mic is mimicing the figure 8s front side. RIGHT would then be the back side. But RIGHT is now looking in the negative, with regards to the other mic. But because of the cancellation it is totally sucking up the sound of LEFT. A true figure 8 mic has a true front (+) and back (-). To make RIGHT(+) behave as a figure 8s backside (-), you’ll have to flip the phase of this mic only. This way the RIGHT mic will behave in-phase with LEFT and the iPod will be audible again. This is how to achieve that; put a trim-plugin (or any plugin with a phase button) in the S2 channel and flip the phase. Route these two mics into a bus and call it “S1”. Done, you have created the first figure 8 signal.
To create the second S duplicate the S1-bus and call it “S2”. As you know, MS needs 2 figure 8 signals with one of them out-of-phase. Again, take a plugin and flip the phase of “s2”. You still don’t hear sound because these 2 signals are cancelling out each other (as it should with this setup). We still need to pan the 2 busses hard left and right and gang the 2. And there you are; now you’ve got 2 S signals needed for the M/S setup.
Now you’ve got two S signals, you can mix them with the M signal. And there you are, in total control of your Mono component and with a brilliant stereo image but without the need of a true figure 8.
Have a listen to the example on SoundCloud. The first part is only the M mic. At 18 seconds you’ll hear the S1 and S2 coming in at 50%. Later on (at 31 seconds) they are at 100%. The end is purely mono to show the big difference. Enjoy!