Recording - February 2010 - 17

of the mic. This is an elemental example of signal-to-noise ratio: the ratio will be improved if the singer is the loudest sound the mic “hears”. Years of experimentation with baffling has convinced me that unless a baffling system is air tight, it’s no silver bullet sound eraser, but really only serves to act as a combination of damping and filtering. In the case of a vocalist on the floor, I’ll usually use baffling, but not very much—just enough to adjust microphone polar pattern coloration issues. Polar patterns to the rescue Discussing the reasons for and behavioral characteristics of microphone polar patterns is an article in itself. For the purpose of this article, I’ll assume the reader knows at least a little bit about this subject. I don’t think I’m going out on a limb to say that most engineers prefer a cardioid pattern for recording vocals. Since the cardioid pattern exhibits a moderate amount of “rear rejection” (the microphone is less sensitive to sounds emanating behind it than it is to sounds emanating in front of it), the sounds in front of it tend to sound a little more powerful and focal than if the mic was set to omni. Also, cardioid mics tend to exhibit the “proximity effect”, whereby the bass response of the mic increases as the sound source’s distance from the mic decreases. A singer can “work the mic” to get more bass from up close. The problem with the cardioid pattern is that sounds in the area it “rejects” exhibit a property known as coloration. Coloration indicates that the frequency response in the mic’s area of rejection is different than in front of the mic. The coloration is usually not a particularly flattering sound, so if I have a singer on the floor, my main thoughts about taking advantage of the mic’s rear rejection are to first aim the microphone in such a way that the loudest sound sources behind the mic are aimed at its least sensitive response area. To know where this least sensitive area is requires careful listening, and it’s never a bad idea to consult the paperwork or manufacturer’s web page to inspect the polar pattern response of a particular mic. A good polar pattern response diagram will not only graphically show the geometry of the mic’s sensitivity, but will also show pattern-related frequency response. Once I’ve aimed the mic to take maximum advantage of its polar pattern response, then I’ll usually put up a baffle that blocks direct sound from entering the rear of the mic. In a good-sounding studio with pleasing hang time, doing this will not seriously reduce leakage into the vocal mic, but at least it will force more sound into the front of the mic, where coloration won’t RECORDING FEBRUARY 2010 play as much of a factor in shaping the frequency response of the sounds the engineer is trying to reject. Singers who play How many times have you tried to track a singer who’s simultaneously playing an instrument, and wished you had better isolation on both the vocal and the instrument? Just as in the vocal-on-the-floor marriage described above, the performer’s instrumental and vocal performances will be married together, and it is the producer’s responsibility to point that out. The one exception to this rule is when a DI signal can be taken on the instrument. In this case, even if the vocal performance is no good, the DI signal can live. I find this to be an extremely useful tactic, even with an acoustic (electric-acoustic) guitar performance. In addition to the ubiquitous internal piezoelectric pickup found in many contemporary acoustic guitars, I also like to use a soundhole pickup, recording a DI signal of that, either as insurance for later, or to be used immediately to enhance the miked sound. On many occasions this technique has meant the difference

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Recording - February 2010

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