Microphones play a crucial role in audio recording, and as a music producer, it is important to have a discerning understanding of their types, applications, and optimal usage scenarios. Microphones exhibit distinct characteristics, with some tailored for specific recording purposes, while others impart unique warmth and character to sound.
This chapter aims to explain the fundamental principles underlying microphone functionality and offers a comprehensive overview of the various microphone types available.
The fundamental function of microphones lies in capturing sound vibrations and converting them into electrical signals. This process hinges on a crucial component known as the diaphragm, which varies in size and is commonly constructed from materials such as plastic or metal. Conceptually, a microphone can be regarded as a reverse speaker, sharing akin principles involving magnets, diaphragms, and electrical signals.
Analogous to microphone mechanics, the human ear operates by channeling sound waves through its unique shape, directing them to the ear canal and ultimately striking the eardrum. Subsequent vibrations travel into the inner ear, where the cochlea—a fluid-filled chamber housing numerous nerve endings—transforms them into electrical signals transmitted to the brain.
The predominant method of connecting microphones involves the utilization of XLR cables. These three-pronged cables are distinguished by their high-quality construction, incorporating effective interference isolation mechanisms. This design serves to mitigate external noise, thereby safeguarding the integrity of the recorded signal. The superior performance of XLR cables comes at a cost, contributing to their relatively higher price point.
It is noteworthy that certain microphones offer alternative connectivity options, such as USB connections or TRS 1/4-inch jack inputs. However, it is advisable to refrain from employing these alternatives in a studio setting due to their inherent limitations in delivering audio quality comparable to that achieved with XLR cables.
Microphones can be broadly categorized into three major types, each distinguished by its unique operational principles, inherent characteristics, and their use cases. It's important to understand these microphone types as microphone choice can save hours of EQ-ing after recording. It's always better to get something sounding good as you record it instead of trying to fix it with effects. It's also important to know what type of microphone you're dealing with because if you misuse them, some microphones are easily breakable, and you don't want to break something that costs 100's of dollars when you start purchasing studio quality mics.
Record like you can't mix, mix like you can't master.
Dynamic microphones represent the most prevalent microphone type due to their widespread use and versatility. Renowned for their durability, they offer a straightforward plug-and-play experience, capable of withstanding high-volume transient sounds, such as those produced by drums, without damaging the diaphragm. The operational principle of dynamic microphones involves the physical movement of a diaphragm connected to a metal coil, generating an electrical current through interaction with a magnet. This minute electrical current is then transmitted through a cable to the audio interface, requiring amplification, typically facilitated by a preamp in studio settings. It's worth noting that each preamp can impart its own character to the signal depending on brand and model.
Dynamic microphones find extensive use in live performances owing to their durability and user-friendly nature. However, they also hold a valuable place in studio environments, particularly when confronted with high-volume and sound pressure wave scenarios, making them well-suited for tasks like miking drum kits. Notably, dynamic microphones operate without the need for Phantom Power, and even if accidentally subjected to it, they will function without adverse effects.
A distinctive characteristic of dynamic microphones is their susceptibility to the proximity effect (Something that we will explore in later chapters). Exploiting this effect can be employed as a recording technique, especially when seeking to enhance low-end frequencies for added warmth by positioning the microphone closer to the sound source.
Condenser microphones present a notable departure from the characteristics of dynamic microphones in several key aspects. A fundamental distinction lies in the requirement for "Phantom Power," an electrical supply typically provided by a mixer or Digital Audio Converter (DAC) to enable audible sound production. This sets them apart from dynamic and ribbon microphones, which operate immediately upon connection without the need for phantom power.
Primarily favored in studio environments, condenser microphones excel in capturing intricate sound details, offering a brighter and clearer sonic character. This capability stems from their utilization of thinner diaphragms, rendering them more sensitive to sound pressure waves. However, this heightened sensitivity also renders condenser microphones more fragile compared to their dynamic counterparts.
Owing to their delicate nature, condenser microphones are generally unsuitable for close proximity to loud instruments such as drum kits. Nevertheless, they find application as overhead or room microphones in drum kit setups. Caution is exercised to avoid close-miking extremely loud sources, like a kick drum, which poses a risk of damaging the thinner diaphragm inherent to condenser microphones.
ChatGPT can explain this much better than I can as I am not an electrical engineer.
On audio consoles or Digital Audio Converters (DACs), phantom power is commonly labeled as +48v. Engaging the +48v button on the respective channel activates the 48 volts needed to power connected condenser microphones.
To protect your microphone, you should turn off phantom power before connecting or disconnecting it!
Ribbon microphones, while less common in typical recording setups, offer unparalleled detail in audio capture. Their distinctive trait lies in being the most delicate among microphone types, attributed to the exceptionally thin diaphragm—a lightweight piece of metal suspended between magnets. Similar to dynamic microphones, ribbon mics do not require phantom power, and mistakenly applying it can lead to damage.
One notable departure from conventional microphone design is the use of a rectangular diaphragm in ribbon mics, as opposed to the more standard circular diaphragm. While the diaphragm's shape minimally influences its sonic character, it serves as a recognizable feature when identifying and working with ribbon microphones.
Ribbon microphones possess unique characteristics distinct from dynamics and condensers. Historically prominent in early studio recording, some enthusiasts argue that ribbon mics offer a more accurate representation of how humans perceive sound. This attribute contributes to capturing a natural, realistic sound that remains faithful to the original source, in contrast to the coloration introduced by dynamics or condensers.
An inherent quality of ribbon mics is their naturally bidirectional pickup pattern. The thin diaphragm vibrates when sound is received on either side, creating a unique sensitivity to the sound source. The thin sides of the diaphragm, however, remain unaffected by sounds approaching from the sides, contributing to the distinct bidirectional nature of ribbon microphones.
For more information on ribbon mics, Sweetwater has a good article on Ribbon Mics & How they work.
Although not a prevalent choice in studio settings, Piezo microphones find niche utility in specific sound design scenarios. Their common deployment in electric acoustic guitars attests to their capability to capture the vibrations of the instrument's body as an audio signal. However, the characteristic tinny sound associated with Piezo microphones limits their widespread adoption in conventional studio recording.
Beyond conventional recording applications, Piezo microphones offer creative possibilities. For instance, the output of a Piezo mic can be employed to trigger musical notes or other effects. Given their versatile nature, these microphones can be affixed to various objects, effectively transforming any inanimate item into a trigger for manipulating parameters within a DAW.
Pickup patterns determine the directional sensitivity of a microphone, indicating the specific direction from which it "listens" to incoming sound. This characteristic is crucial in ensuring that the microphone captures audio only from the intended source while minimizing background noise from other directions.
Some microphones offer the added flexibility of adjustable pickup patterns, allowing users to tailor the microphone's directional sensitivity to their specific recording needs. This feature enhances versatility in various recording scenarios.
It's important to be mindful of the correct orientation for holding a microphone, as this can vary between models and brands. While some microphones require speaking into the top of the grill, others may necessitate positioning the side of the mic to your sound source. The specific guidelines for mic orientation depend on the mic type, with a general rule of thumb suggesting that dynamic microphones are typically spoken into from the top, while condenser mics are used side-on. Always refer to the manual of your microphone for precise instructions to ensure proper usage.
Omnidirectional microphones exhibit a unique pickup pattern by capturing sound from all directions without rejecting any source. While this may not be the preferred choice for many studio applications, it serves a distinct purpose. In live performance recordings, a stereo pair of omnidirectional microphones can faithfully capture the entire ambiance and room sound, providing an accurate representation of the performance.
In studio settings, omnidirectional microphones find prominence as room mics, especially when aiming to capture the ambient characteristics of a space. This is particularly valuable in recording drum kits, where the goal is to achieve a broader, more expansive sound by incorporating the room's natural acoustics.
Notably, omnidirectional microphones lack the proximity effect observed in other pickup patterns. Regardless of the distance from the microphone, there is no noticable boost to lower frequencies. This absence of proximity effect stems from the uniform pickup of sound from all directions, contributing to the versatility of omnidirectional microphones in various recording scenarios.
Cardioid microphones, distinguished by their heart-shaped pickup pattern, are widely favored due to their directional focus, enabling users to concentrate on sound from a specific direction. When using a microphone set to a cardioid pattern, the impact of this directional sensitivity becomes apparent. As you rotate the microphone while singing into it, you will observe a noticeable alteration in the captured sound as you move beyond the defined range of the cardioid direction.
Notably, when you turn 180 degrees away from the "front" of the microphone, the sound diminishes significantly. This phenomenon occurs because cardioid microphones selectively capture sound primarily from the front while minimizing sensitivity to sounds originating from the rear. This directional attribute is advantageous in isolating the desired sound source and minimizing background noise or interference from other directions.
Hypercardioid microphones, as the name implies, represent an intensified version of the cardioid pattern, exhibiting an even more pronounced focus on a specific direction. Often embodied in the form of "Shotgun" or "Pencil" microphones, these slender and elongated devices excel at capturing sound from considerable distances while minimizing the impact of background noise on the recorded signal.
Commonly utilized in settings like sporting events, hypercardioid microphones, especially in the form of shotgun mics, are employed to isolate specific sound sources, such as players, from the ambient noise of cheering crowds. The elongated design of these shotgun microphones serves the purpose of maximizing rejection of sound from directions other than the intended target, contributing to the precision in directional capture.
The use of hypercardioid microphones proves invaluable in scenarios where precise, long-range sound capture is paramount, offering a focused and isolated recording amidst challenging acoustic environments.
Bidirectional microphones, characterized by a figure-8 pickup pattern, essentially consist of two mirrored cardioid patterns—one for the front and one for the back. This configuration results in sound capture from the front and back while rejecting sound from the sides. Despite its unconventional appearance, the bidirectional pattern serves various purposes, offering a practical solution for recording in two directions without the need for a second cardioid microphone.
One notable application of the bidirectional pattern is in the mid/side recording technique, a concept explained in later chapters. This technique leverages the bidirectional pattern to capture ambient information (side), along with a central microphone (mid) to capture direct source information, allowing for a nuanced and adjustable stereo image during mixing.
Bidirectional microphones also prove beneficial when recording two sources simultaneously. For instance, two singers can share one microphone, with each singer positioned on opposite sides. Additionally, bidirectional mics find utility when the objective is to capture both the primary sound source and the ambient room reflections, striking a balance between directionality and room character without the tonal neutrality associated with omnidirectional microphones.