A good friend of mine and amazing drummer, Lloyd Martin, was at the studio a little while ago to tune up and service the drum kit; as we do on a regular basis. I enjoy these times, as we get to pull out the microphones and experiment with different techniques and sound ideas.
I thought it would be a great opportunity to show you stereo miking technique. You can check out the the mix in the DAW in the video at the end of this blog
In this session, I close miked the kit, but; I double miked the kick using dual diaphragm microphone so have both condenser and dynamic on the kick, then double miked the snare; and close miked, hats, rack tom 1, rack tom 2 and floor tom; and used the spaced pair technique for Overheads left and right.
I used the Lewitt Drum Microphone Kit, for kick, toms and a matched pair of LCT 340s for overheads; with the overheads in a spaced pair configuration and omni capsule. I used my gem of a find el cheepo Leem microphone for the hats (seriously this microphone cost about R500.00, I’ve had it for 15 years; and I have used some of the most expensive branded microphones in sessions; but this little Leem, it just gives me the sound I’m looking for every time!), and Shure SM7 for the snare top and bottom.
As you will see in the video session and from the pictures, there are already 10 microphones on the kit. Nice!
Now, there are various stereo miking techniques available to us as audio engineers. XY and spaced pair probably jump to your mind straight away, especially the XY technique, as it closely replicates human hearing.
There is another, lesser used technique, known as mid side or MS. It is a little more complex, but offers some advantages over the standard stereo miking techniques.
A little bit of History
Mid/Side was devised by an EMI engineer and early pioneer of stereophonic and surround sound, Alan Blumlein in 1933/1934
So it’s also called the Blumlein technique. He was a smart guy. Blumlein patented the technique in 1933 and used it on some of the earliest stereophonic recordings, but extensively in broadcast, due to the fact that M/S tracks are always mono compatible.
But M/S isn’t just for broadcast; it offers such a cool sound and flexibility for studio recording, and because the technique is so flexible and convenient; it’s good for live sound applications too. The Mid-Side miking technique is one of the most effective ways to add some stereo width to even the most basic recordings. There are many more ways by which this could be implemented, and most of them can produce some pretty amazing results.
The M/S technique gives you more control over the depth/width of the stereo spread than other microphone recording techniques, and allows you to make adjustments at any time after the recording is finished.
What You Need
While XY recording requires a matched pair of microphones to create a consistent image, M/S recording often uses two completely different mics, or uses similar microphones set to different pickup patterns.
In this session I used a Shure SM57 as the centre microphone (cardioid pickup) and the Lewitt LCT 640 (switched into figure 8 or Bi-polar pattern). Both mic capsules should be placed as closely as possible, typically one above
the other. The placement of these microphones is what was the fun part. Right in between the toms just underneath. Have a look at the pictures.
How does it work?
The M/S recording technique is actually not all that complicated. The concept is that the Mid microphone acts as a centre channel, while the Side microphone's (aimed at 90 degrees from the source), picks up ambient and reverberant sound coming from the sides of the sound stage. The important thing to realize here is that the two sides are 180 degrees out of phase . A positive charge to one side of the mic's diaphragm creates an equal negative charge to the other side. channel creates the ambience and directionality by adding or subtracting information from either side. usually the front of the mic, which represents the plus (+) side, is pointed to the left of the sound stage, and the rear or minus (-) side points to the right.
How do you record the MS technique?
You will record the signal from each microphone onto its own track. Then, to hear a proper stereo image when listening to the recording, you need to matrix and decode the tracks. Ok, so, you have recorded only two channels of audio (the Mid and Side).
This simply involves splitting the side signal into two channels.
1. duplicate the Side signal onto another channel in your DAW. You will now have two separate channels for the side microphone with the same content. Remember though, that the info will be 180 degrees out of phase
2. reverse/invert/flip the phase on one of the Side channels
3. then pan one of the Side channels hard left and the other hard right
4. this will let you hear the sound as captured by the side mic set to a figure-8 pattern.
So, you've got three channels of recorded audio — the Mid centre channel and two Side channels, one of which has been phase inverted. By setting the levels of these three signals, you can create the stereo image that you want.
You will notice that the sound from the mid channel is in mono. In order to get the stereo image, you will have to blend in the two side channels.
What’s really cool about this is that simply increasing or reducing the blend of the side channels in the mix will give you more or less stereo width. The effect is impressive! If you listen to just the Mid channel, you get a mono signal.
When you start to turn up the two side channels, aah the wonderful happens; you'll hear a nice stereo spread. The really awesome part is that you have control over the width/depth of the stereo field by adjusting the amount of the side channel you push into the mix.
This is the flexibility of the MS technique. You can create a wider/deeper or narrower stereo field/image after the material has been recorded; which is impossible to do using the XY technique. The other benefit of the MS technique is true mono compatibility. The two sides cancel each other out when you mix to mono; leaving only the centre, giving you a perfect monoaural signal. The side channels contain the room ambience; so when you collapse the mix to mono; that ambience is eliminated and you are left with a more direct, focused mix, with an increase in clarity.
You can also experiment with using an omni mic pattern on the Mid channel. This will really increase spaciousness and you’ll also get more low frequency response. Using different microphones will also help you add ‘colour’ to the sound.
In the video, you will have a chance to hear the microphone techniques in action. There is an SSL Mix Buss compressor n the Master Buss, just to manage any unnecessary nasty surprise peaks. There is an EQ to attenuate excess low end on the rack tom, but other than that the kit is just raw, no effects added. Enjoy!
That’s it from me. Catch you next time!