Choosing The RIght Microphone For Every Scenario
One of the things that made the biggest differences in the quality of recordings I do is knowing how to choose an appropriate a microphone for every scenario I encounter. Being able to play to each types strengths, and use polar patterns to your advantage will go a long way to ensure you capture every source tas cleanly as possible. Better understanding each one will help inform the decisions you make as a recordist no matter what situation you encounter.
Most people who work with audio are probably familiar with these four types of mics; Dynamic, Condenser, Ribbon, & Lavalier Mics. Each type of microphone has different characteristics due to the nature of its design
Dynamic Mics work using a moving coil (much like a speaker) to convert vibrations into an electrical signal. Known for being rugged and handling high volume sources well, dynamic mics are completely passive in nature. When compared to condenser mics, they have a much slower transient response since it requires a lot more energy to move the coil. This can be flattering on many sources, but on others can sound like a lack of detail.
Condenser Mics (Sometime called Capacitor Microphones, since their diaphragm is a capacitor that varies in capacitance based on the interaction with sound vibrations) yield an extremely detailed sound. Having excellent transient response, they reproduce the the most ‘lifelike’ sounds of any type of microphones. Most condenser mics fall under one of two styles based on their diaphragm size.
Large Diaphragm Mics
Having a larger diaphragm increases the sensitivity and inversely lowers the noise floor. Originally Large Diaphragms were necessary to overcome the noise floor of the tube circuitry of the time. As technology improved, the noise floor became less relevant. As a result of the larger diaphragm, they tend to be a little more colored (Especially when off axis) then their small diaphragm counterparts. This coloration a lot of times is very flattering to the source, giving it a larger than life sound.
Small Diaphragm Microphones
The main advantages to small diaphragm is an increased transient response (Especially for High Frequencies), as well as less coloration to off axis bleed. Small Diaphragms are generally chosen for their transparent, true to life sound. Their form factor also is helpful for tight placements or on the end of a boom pole. Small Diaphragm polar patterns generally remain more consistent over the frequency spectrum, yield excellent results when used in stereo arrays.
Among the first microphones ever developed, ribbon mics work similarly to dynamics but instead of a moving coil, a thin aluminum ribbon is suspended between coils. Ribbon mics are best known for having a subtle high frequency rolloff that lends them to sounding ‘warm’ when compared to other microphone types. This can be helpful for preventing especially bright sources from sounding harsh. One of the major disadvantages to ribbon mics is they are fairly fragile. The majority of Ribbon Mics are Bi-Directional in nature due to their design, but there are exceptions to this.
Lavalier Mics while most similar to condenser mics, I consider them their own category. They require a much different bias voltage, and perform a bit different due to their miniaturized design. Generally used for recording dialog with them hidden on talent, they occasionally make their way into music recording as well. For example Steve Albini is known for using one as kick drum batter microphone to capture the attack.
Polar Pickup Patterns
Understanding microphone pickup patterns can help mitigate problems at the source. For example to help reject unwanted sounds, make tonal adjustments, or tailor stereo width. Pick up patterns are fairly straight forward.
Cardioid is probably the most common pickup pattern you will encounter. Sometimes called Unidirectional, it picks up from the front, and rejects from the rear. For studio recording, more often than not, you’ll want to use this pickup pattern.
OmniDirectional mics pickup from all directions. Having a wide pickup pattern can be useful to prevent a moving source from going off axis, or recording sounds coming from multiple directions. As an effect of the omni pickup pattern they don’t exhibit proximity effect. This phenomena can be extremely helpful when close micing sources but you don’t want the added low bump from its proximity. Most lavaliers you’ll encounter are omnis, and this helps prevent head turns from effecting tonality, as well as reduced handling noise.
Bi-Directional Mics (Also called Figure 8) pick up from the front and the back, while rejecting from the sides. Inversely to omni mics, bi-directional mics experience the most proximity effect. This can be helpful if you are looking to add some body to the source. When dealing with unwanted bleed, the side rejection having the deepest null of any pickup pattern is especially helpful.
HyperCardioid, Super Cardioid, & Wide Cardioid
Hypercardioid & Supercardioid are the patterns between cardioid & bi-directional, yielding a narrower pickup then then cardioid, with only a little bit of rear pickup. Wide cardioid sits between cardioid & omnidirectional.
Shotgun or Lobular
Usually based on a supercardioid or hypercardioid capsule, shotgun mics use an interference tube to make their pickup pattern even more narrow & focused. Shotguns work well for recording dialog outdoors as they handle rejecting sounds from their surroundings better than other pickup patterns.
Multi pattern mics use two capsules and the phase relationship between them to create multiple patterns out of a single dual diaphragm capsule. In bidirectional mode the rear capsule is phase reversed from the front capsule, as you shift 90° around to the sides the microphone each they create nulls but being 180° out of phase at the edges. For omni the capsules use the same phase polarity.
Common Use Scenarios
Depending on what & where you are recording will determine what mic you choose, but here are a few common scenarios for film sound as well as studio recording. There are no hard and fast rules, and as long as there is sound reasoning behind your choice, it will likely work out.
With sound for film, you are constantly recording in different environments. Capturing clean dialog is the utmost concern of a production sound mixers, so tailoring the mics to each situation is essential.
Outdoor Film Dialog
If you are lucky enough to have a very quiet outdoor location, recording dialog outside can be a real dream. There are no acoustics to get in the way, so most of the problems you are fighting are noise related. Outdoor sounds are hard to control so having an incredibly narrow pickup pattern helps isolate the sounds you are trying to capture from the ones you aren’t. This is where shotgun microphones shine. A few examples that stand out in my mind are the DPA 4017 & Schoeps CMIT5U.
Indoor Film Dialog
A well placed boom will always have a better quality of sound then a lavalier. For capturing dialog indoors I like a supercardioid or hypercardioid mics, which with a more narrow pickup pattern, it can help downplay acoustic problems and unwanted sounds. For scenes that require a lot of panning on the boom, a cardioid mic can make it easier to avoid missing lines. I avoid shotguns indoors since the interference tube & rear pickup can bring out more early reflections and comb filtering.
Wide shots are where wireless lavalier microphones really come into play. While more susceptible to clothing ristle, the can be a life saver where the shot’s framing prevents it from being boomed. That being said a little boom from a distance mixed in can help with perspective. The best sounding lav mics I’ve heard that cut reasonably well with a boom are the DPA 4060 & Sanken COS11.
High Noise Environments & ENG Interviews
For Electronic News Gathering or high noise scenarios dynamic mics are going to perform best when isolating background noise. Omnidirectional dynamics work great for reporters and event interviews, because no matter how they hold the mic they will be on axis with a consistent tonality. While omni dynamics do a fair job with noisy environments, for higher noise handling, a switch to a cardioid dynamic can help with bleed. My two go too mics are the Electro-Voice RE50 & Sennheiser e835.
Studio recording, especially for music production, leaves a lot of freedom for creative interpretation, and a lot of it will be contextual to every other instrument in the mix. Fortunately Bad Racket has a good variety in our mic collection.
Overheads are an overall picture picture of the drumkit and the primary sound of the cymbals. I like using a pair of cardioid large diaphragm in a spaced pair stereo configuration. For a more transparent and detailed sound I sometimes instead opt for a pair of small diaphragm condensers. My favorite overheads are AKG C414 EBs.
Drum Close Mics
I rely heavily on dynamic mics heavily for close mics on drums. Snare tends to have problems with high hat bleed, so a hypercardioid, like a Beyerdynamic M201, can help with that. For kick drum, a cardioid or bi-directional with good proximity effect works well. Shure Beta 52a, Electrovoice RE20, Shure Beta91A, AKG D12, and AKG D112, are all great options. Toms I find a standard cardioid dynamic works very well, my go to is a Sennheiser MD421.
Room mics for Drums & other instruments can go a long way towards creating a sonic aesthetic that enhances the music. It’s an essential part of a drum kit sound. This is something that isn’t very constant for me, I frequently hop between mono, XY, Mid-Side, Spaced Pair with Cardioid or Omni Mics, Blumlein Pair, and many more. Be creative and find something that serves the sound you are after.
To my ears, acoustic instruments sound the most natural with omnidirectional large diaphragm condensers. My favorite is AKG C414 EBs in Omni. Small diaphragm & shotguns can work well as spot mics for orchestral ensembles. I’ve had good luck with both my DPA 4017 & a modded pair of Oktava MK012s.
Bass amps I look for a cardioid dynamic that reproduces low frequencies well. Since I’m getting right up on the cranked speaker to maximize proximity effect, it needs to handle loud sources well. This application would likely destroy a ribbon mic. My two favorite mics for bass are Electro Voice RE20 & Sennheiser MD421s, depending on the sound I’m after.
Electric guitar again is one that varies significantly from session to session. I tend to like the tight detailed sound of condenser mics on guitar, but dynamics work equally well. I’ve been equally successful with 2 mics blended as a single mic on its own. It all depends on the sound you are after. Some of my favorite guitar mics are AKG C414EB, Neumann U87, & Shure SM57.
Vocals & Voiceover
Everyone’s voice sounds a bit different, and microphones aren’t a one size fits all when it comes to recording vocals. The same mic could sound full, rich, and warm on one person, and on the next be harsh, thing, & abrasive. Suiting the mic to the person’s voice makes a big difference. Some of my go to mics to try are the Neumann U87, Electro Voice RE20, or AKG C414 EB, but you never know what will work best until you try a few options.
It’s very common to record guitar and vocals together for singer songwriters. To minimize the bleed from guitar & vocals into each others mics, bidirectional mics with nulls pointed to the other source can have a dramatic effect towards phase coherence & clarity of each source.