By Ken Lanyon (Slider)

For this article, I thought I would address something that is crucial to getting great sounds on tape but often overlooked. Many of you may have heard of phasing, but haven't fully understood what it means or how to use it to your advantage (and no... it has nothing to do with Star Trek).

Phasing has to do with the positioning of multiple mics on a single source, and the sonic result of the two blended sounds. These two sounds may be recorded onto separate tracks or summed to one for saving track space, but the bottom line is that you need to account for potential phase problems every time you do this. While you can double-mic anything, like guitar amps or a piano, drums are a commonly multi-miked instrument. This being said, I am going to be using a drum set for my main examples. So, put on your thinking caps, and lets learn a few things.

You may be surprised that miking a drum set requires planning. You cant just throw mics up and expect to get the best sounds you have ever heard. Great drum tracks come from a combination of proper mic choices, good mic placement, decent preamps, and, of course, good playing. You will find that different mics sound better in different positions, and this is especially important when two mics are involved, such as a snare miked on the top and bottom heads. Obviously, physics is an inherent part of music, so let me first explain what phasing actually is. If you haven't already read my article on soundwaves, I recommend you do that before going on in this one, especially if you don't know much about how sound works.

Every instrument creates soundwaves for each frequency covered in its range, and each frequency has a specific wavelength. These waveforms look like a rising and falling wave, each having a peak and a dip in one complete cycle. A peak occurs at 90 degrees and the dips at 270 degrees, with a complete cycle lasting 360 degrees total. Now, when you are using multiple microphones to record the same source, these frequencies are usually going to arrive at the two microphones at different times, each being in a different part of the cycle. The whole waveform is still accurately represented, but the microphone further away from the source is recording a delayed waveform. With our example of miking a snare drum, the top mic picks up the direct waveform from the surface of the drumhead, but the bottom mic receives a delayed signal as a result of the soundwaves having to go through two drumheads and forcing them to react to it. So you can see where the second mic may pick up the signal in a completely different point of the cycle than the first mic.

Figure 1 - Sine Wave

Compliments of © Alexander Magazine

Let me expand on this concept again. Obviously, a musical source is going to create a spectrum of frequencies when played, and because each frequency from a source has a specific wavelength, their waveforms will be at a certain positions when they reach both microphones and are converted to electrical energy. Microphone 1, which is closest to the source, will record a certain frequency having only completed half of it's waveform, whereas microphone 2 (a few more inches away from the source) will pick it up as having completed 1 full cycle of its waveform. Thus, when the two certain frequencies are played back at the same time, that frequency is going to be canceled out completely. This is because one is in its dip and the other is in its peak, both at the exact same moment. Each individual cancellation would then be considered 180 degrees out of phase.

Figure 2 - Phase Cancellation

Compliments of © Alexander Magazine

Next Page >>