For this tip, we will examine a recording of Mid-Side acoustic guitar. Below is a list of the tracks and the equalization measures and other processing that was applied to each track. For this application, a single cardioid microphone is used to capture the guitar, placed directly at the point where the neck meets the sound hole. A second microphone set to a bi-directional pattern is placed perpendicular to the guitar. The mid-side “trick” is to place the first mic in your mix, then use a plugin, console, or DAW tracks to duplicate the second mic, pan both hard left and right, then flip the polarity of either the left or right panned track. In this example, we used a Shure SM81 as the mid microphone and a Shure KSM44 as the Bi-directional side microphone. The room mic was an AKG C414 ULS set to an Omni-directional pattern. For the DI track the signal went through a Whirlwind Director DI box.

Mid Microphone Track

Plugin: Brainworx bx_hybrid V2 mix

This plugin is great for identifying tonal problem areas in track. In this instance, a high pass filter was engaged at 100Hz with a 12dB/octave slope. Additionally, 10.5 dB of 170Hz was cut to eliminate a boxy resonant frequency in the guitar that was very prominent. To add a bit of pick attack, 6kHz was boosted with a medium Q then 3dB of output gain was added to compensate for the level lost by the EQ cuts.

Side Microphone Tracks

Plugin: Brainworx bx_cleansweep Pro

All that was needed for these tracks was a simple high pass filter and Cleansweep was perfect for the job. Both filters were set to 150Hz, and the polarity of the right was side was inverted to apply correctly the stereo image of the bi-directional side microphone. This applies the “side” effect mentioned above. 

DI and Room Mic Tracks

Plugin: Brainworx bx_cleansweep Pro

To add to the overall tone of the acoustic, the guitar’s pickup was captured with a direct box and an omnidirectional room was recorded. Both tracks were given high pass filters. The DI track was set to 100Hz, and the Room Mic track was set to 250 Hz.

Stereo Compressor

Plugin: Vertigo VSC-2

All of the acoustic guitar tracks were bussed to a stereo group that had the stereo Vertigo compressor applied to it. The threshold was set to -13.2, so it just lightly worked on some of the harder accented strums. The ratio was 4:1 for a small amount of gain reduction. Attack time was 30ms to allow the pick strikes to pass before compression began. I found the Auto release time to be perfect for this instance. 

As you can hear in the “after” recording example, when the side mic is added, the effect spreads the guitar wider across the stereo field. Although extreme in the “after” example, you can pull back the side effect by reducing its gain in the signal.

TRY THIS: Download the processed Mid Mic.wav, Side Mic L.wav and Side Mic R.wav files and import them into your DAW. Group the Side Mic L and R files, pan them hard left and right and bring the faders all the way down. Next, bring the Mid Mic.wav fader to unit gain (0 dB), pan it center, then slowly bring up the grouped Mid Mic faders to hear the Mid Side stereo effect in the mix. By varying the amount of Side mic, you can alter the depth of the stereo effect.


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