Recording Tips and Tricks: Microphones & Microphone Placement
By Kelly Garner
Microphones: Choose Wisely
Choosing the correct microphone for each instrument is one of the most important steps in the recording process. Each instrument, whether it be a voice, a guitar or a keyboard, contains different amounts of various frequencies across the frequency spectrum, making the tone characteristic of these instruments sound completely different from one another.
A bass guitar has more low-end frequencies than a piccolo. A soprano voice has more high-end frequencies than a baritone-bass. In the same way, microphones exhibit different frequency characteristics themselves. Most microphone manufacturers supply a frequency response graph with the purchase of each microphone. This graph, which can also usually be accessed online, shows the frequency response tendencies of each microphone. For instance, when looking for the perfect microphone for an upright bass, you would not want to use a microphone that has a big bump in the low-end of the frequency response graph. Also, if you are working with a soprano that has a brighter than usual voice, you would not want to use a microphone that has a bump in the mid- to upper half of the frequency response graph.
For upright bass, I would use a Neumann U-67, a microphone that is also frequently used on tenor voices. This microphone is known to work well when recording male voices because it has a fairly flat frequency response, but adds a little pop or high end to the voice while still capturing the low vocal frequencies. In the same way, when recording an upright bass, this mic would add a little snap to the sound. The added “snap” will not be a “tiney” sound, but just a nice boost on top that will capture the upper frequencies of the upright bass a little more pristinely.
Like acoustic bass, male vocals are usually captured best by a large diaphragm condenser microphone because the larger surface area of the large diaphragm condenser is more conducive to capturing the long waveforms of the lower frequencies. Conversely, if the goal is to find the perfect microphone to capture the high-end frequencies of cymbals, one would probably want to try a small diaphragm condenser microphone like the Nuemann KM-184 for overhead microphones. Because of the small surface area on the small diaphragms, these microphones pick up the high frequencies, but leave out the lower frequencies that contain the larger waveforms. The high glossy sound of the cymbals is mostly what one would want to capture with overhead microphones. For instance, one would not want to pick up any more of the kick drum than needed or the engineer will not be able to equalize the cymbal track appropriately.
All vocals in general are best captured with a large diaphragm condenser because it picks up the lower frequencies contained in the human voice while also capturing the upper frequencies. The upper frequencies in the voice are also very important because of the need to hear the breath or air around the voice. This characteristic is what makes the voice feel natural and “real.” For example, if an engineer overuses a “de-esser” when mixing and completely takes away the “hiss” on the singer’s “S’s,” the singer will sound like they have a “lisp.” So, obviously, capturing the high frequencies of a vocal is of utmost importance to maintaining the integrity and authenticity of the singing voice.
Microphone Placement: Getting it right!
The way in which a microphone is place in front of or pointing at an instrument is also imperative to a pristinely recorded sound. For instance, the Sennheiser 421 mics that are frequently used for Toms are normally pointed at the striking point of the Tom to pick up the best sound. Some people like to focus them a little more towards the rim to pick up more “tone” than “strike,” but nonetheless, a difference of no more than an inch or two in placement.
When recording vocals, large diaphragm condenser microphones are usually hung upside down “up and over” a music stand on a large studio boom stand. The diaphragm of the microphone should be somewhere around the same height as the singer’s nose and upper lip when the singer is standing and singing in front of the microphone. Windscreens or “pop” screens should always be placed between the microphone and the singer when recording the voice. Sometimes it is even better to use two windscreens positioned in a “V” formation, with the closest windscreen never positioned parallel to the diaphragm of the microphone. When the breath hits the windscreen, because it is not parallel it will be deflected in a slightly different direction, thus not hitting the diaphragm of the microphone and causing a “pop.”
A dynamic Shure SM-57 microphone, (often used to record a guitar amp/cabinet), should always be placed a little outside of the center of the speaker cabinet. You do not want to put the mic directly over the center cone, but to the outside where there is more tone coming through the cabinet.
Getting the placement of microphones correctly positioned on instruments is imperative to capturing an accurate version of each instrument. Although some of these adjustments may amount to a matter of inches, it will translate to a difference of miles in terms of improving the quality of the recording.
Dr. Kelly K. Garner is an Assistant Professor of Music, Belmont University, recording artist, and JEN scholarship winner.