Different Types Of Microphones - Sound is a wonderful thing. All the other sounds we hear are caused by the unequal emphasis/minute in the air around us. What's amazing about it is that air transmits pressure changes so well - and so precisely
You already know about the first microphone, the metal diaphragm attached to the needle, and this needle scraped against a piece of metal. The unequal compression of air that occurs when a person speaks to the diaphragm moves the diaphragm, which diverts the needle, which is then recorded on the foil. As the needle then moves back up again to the top of the foil, rubbing against the foil will then vibrate and recreate the sound. The evidence that a purely engineered mechanism works show how much vibrational energy the air has.
Different Types Of Microphones
Microphone Work Step
The microphone is one of the transducers (devices that change energy from one form to another) which converts acoustic energy (sound waves) into electrical energy (audio signal).
There are various types/types of microphones where each type uses another system in energy alteration, but all types of microphones have one thing in common, namely the diaphragm. The diaphragm is a thin material (such as paper, plastic, or aluminum) that vibrates when struck by sound waves. In the same usual grip mic in the following figure, the diaphragm is inside the microphone head.
When the diaphragm vibrates, other elements in the microphone vibrate as well. This vibration is converted into an electric current which then becomes an audio signal.
In the audio mechanism, the loudspeaker includes a transducer whose role is to convert electrical energy into acoustic energy.
Various types of microphones are often used, but in general, microphones are based on the following two:
The type of alteration technology they use
Microphone grouping refers to the technical system used to convert sound into electric current. Common technologies are active microphones (active), condenser microphones (condenser), ribbon (ribbon), and crystals (crystal). Each has advantages and disadvantages is generally more suitable for certain types of programs.
Where the program or microphone benefits it
Some types of mics are designed to be used efficiently and can be used efficiently for various purposes, some are made exclusively and only fit to be used according to their detailed purpose. To compare mics based on benefits, it can be seen from their characters such as direction, frequency response, and impedance
Microphone Level and Line Level
The electric current created by the microphone is very small and is usually called a level mic. Mic levels are measured in millivolts. For this to work, this smallest signal must be line-level (around 0.5 - 2 V). In the form of a stronger signal, line-level as a standard for signal capabilities is used for audio processing equipment and general devices such as CD players, tapes, VCRs, and so on.
The process of amplification or amplification of the signal from mic level to line level usually occurs in the following ways:
- Some microphones are equipped with a small built-in amplifier that can amplify the signal to a high mic level or line level.
- Mic through a small amplifier commonly called a line amp.
- Use a sound mixer that has small amplifiers per channel. The attenuator will accommodate microphones of various levels to match up to a uniform line level.
- The audio signal is sent through a special power amplifier whose role is to amplify the signal so that it can be heard through the loudspeaker.
Active microphones are flexible (versatile) and great for a variety of purposes. Usually have a simple design with parts that can be removed. This type of microphone is relatively strong and more durable. Really suitable for sound with very high volume levels such as certain musical instruments or amplifiers. Active microphones do not have an internal amplifier and generally do not require batteries or external power.
Active Microphone Work Step
Same in science lessons, when a magnet is brought near a coil of wire, an electric current will be created in the wire. Using this electromagnetic concept, an active microphone uses a coil of wire and a magnet to produce an audio signal.
The diaphragm is attached to the coil. When this diaphragm vibrates because it responds to incoming sound waves, the coil will move away from the magnet. This event creates a current in the coil which is passed from the microphone to the cable. In general, the configuration is the same as in the following figure.
As previously mentioned, the loudspeaker has a role that intersects with the microphone, which is to replace the electrical energy of sound waves. This loudspeaker performance can accurately visualize the performance of an active microphone which is essentially a contradiction of the loudspeaker. When you see a cross-section of the speaker, it will be clearly visible with the image above. Even in some intercom mechanisms, the speaker is used as a microphone.
The condenser has an arithmetic meaning, which is an electronic element that stores energy in the form of an electrostatic field. Precisely the term condenser itself has rarely been used but has been coined as a name for this type of microphone, which uses a motor to convert acoustic energy into electric current.
Condenser microphones require power from a battery or other external source. The audio signal created is stronger than the active microphone. Because it tends to be more sensitive and responsive on active microphones, condenser microphones are therefore more suitable for capturing small details in sound. On the other hand, this microphone is not good at working at high volumes because the sensitivity level is prone to distortion.
Condenser Microphone Working Step
A group is divided into 2 plates with an electric voltage between them. On a condenser mic, one of the plates is made of the lightest material and works as a diaphragm. When struck by sound waves, this diaphragm plate will vibrate resulting in a shift in the distance between the 2 plates, resulting in a capacitance shift. Even brighter, when the 2 plates are close together, the capacitance will increase and there will be additional current. When the 2 plates move away from each other, the capacitance will shrink and occur when current occurs.
For it to work, it needs an electric voltage. Electricity can come from the battery in the mic or from another external source.
Electric Condenser Microphone
The electret condenser microphone uses a special motor that has a fixed voltage installed in the production process. It's like a permanent magnet so it doesn't need external power to work. However, good electret condenser mics are generally equipped with a pre-amplifier that requires power to operate.
Each microphone has a character or characters called directionality (measured characters). This property visualizes the microphone's sensitivity to sound from different directions. Some microphones can capture sound from all directions with the same quality, some can only capture sound from one direction or a combination of certain directions.
Directional properties on microphones are grouped into three special groups:
the power to capture the sound of the same quality from all directions
The power to capture sound is more dominant than either direction. This group includes cardioid and hyper-cardioid microphones.
Able to pick up sound from 2 intersecting directions.
Certain microphones are usually equipped with a graphical representation in the manual or promo material to visualize the directional character of the microphone so that it is easy to reach. This graphical representation is usually called a polar pattern. Here are examples of common polar schemes that visualize the directionality of a microphone.
Capture sound equally from all directions
Benefits: For producing an ambient, for situations where sound is arriving from multiple directions, for situations where the mic must be stationary in one state multiple sound sources are moving.
In certain situations, an omnidirectional mic can be really useful, but picking up sound from all directions is generally rare. Capture sound from all directions too broad and not concentrated. If you want to record the sound of a certain subject or place, chances are you will have a hard time with yourself around.
Cardioid which means "heart-shaped" is one of the schemes for capturing sound on a microphone. The most common sound is found from the front and a little space on the sides.
Benefits: Prioritizes sound from the direction where the mic is aimed but there is still room for mic movement and there is ambient.
- The cardioid-type mic is really versatile and great for general use. Generally, holding mics have cardioid properties
- There are several different cardioid schemes (including hyper-cardioid described below)
Here's an overuse versus cardioid scheme. Completely scalable and eliminate the majority of noise from the side and rear. Because of its thin and long hyper-cardioid design, this type of microphone is often called a shotgun microphone.
Benefits: to cover the sound of only one subject or one direction when there are several around, to capture the sound of subjects at a distance.
By eliminating the ambient, the sound from one direction of the cage becomes less common. Inserting recorded audio from another mic will help (eg stable background sound at low volume)
Need to be vigilant to maintain sound stability. If the mic is not always metered to the subject you will lose audio.
The shape of the shotgun can increase the sensitivity to the rear.
Using the number eight scheme and able to capture sound evenly from 2 intersecting directions.
Benefits: Circumstances requiring such a polar scheme are rare. One of the opportunities is when you will be interviewing 2 people who are meeting each other where the microphone is in both.
Multiple microphones give it multiple directional options where you can decide to use the Omni, cardioid, or shotgun scheme.
Generally, you can get this kind of feature on the video camera microphone, so you can adjust the direction with the corner direction and zoom direction.
Although this feature looks really useful, generally microphones with a variable zoom feature don't work well and often make noise when zooming. Using a few different mics will generally give you better results.
In using a microphone, one of the ideas that are often misunderstood or ignored is the value of the microphone impedance. Because maybe the impedance is not seen as one of the necessary factors because the microphone can still be operated properly using the best impedance value or maybe not. However, to make sure you get the best and most reliable audio quality, you should know how to use this impedance factor correctly.
In short, it can be stated that low impedance is better than high impedance.
What is Impedance?
Impedance is an electronic term that calculates the amount of opposition a device has to an AC current (eg an audio signal). Technically speaking, impedance is a combination of capacitance, inductance, and resistance in the signal. The letter Z is often used as a symbol that represents the word impedance, for example, Hi-Z or Low-Z.
Impedance is measured in ohms, which are represented by the symbol (omega). So if a microphone has 600 details it means it has an impedance of 600 ohms.
What Does Microphone Impedance Mean?
All microphones have one detail that refers to their impedance. You'll often find that microphones with hard-wired cables and a 1/4" socket are high impedance, while mics with separate audio cables and XLR connectors have low impedance.
There are three general categorizations for microphone impedance:
- Low Impedance (less than 600Ω)
- Medium Impedance (600Ω - 10,000Ω)
- High Impedance (greater than 10,000Ω)
Some microphones have the power to select a different impedance value.
Select Impedance Value
High impedance microphones are generally pretty cheap. One of the special drawbacks of this type of microphone is that it performs poorly when using a relatively long cable. With a cable as far as 5 - 10 mtr. alone high impedance microphones have resulted in poor sound quality (especially high frequencies). This microphone is not a good option for serious tasks.
Although not completely reliable, the impedance value is one of the considerations to look at the overall quality of the microphone.
Low impedance microphones are better and more disconnected than high impedance microphones.
The following is an example of a Microphone Type
Fiber Optic Microphone
Fiber-optic systems, which use super-thin strands of glass to transmit information instead of metal wires, have revolutionized the telecommunications sector in recent years, including microphone technology. So what's the problem? Unlike conservative mics, which are often large and transmit electrical signals, fiber optic microphones can be quite small, and they can be used in electrically sensitive environments. They can be made without metal, which makes them particularly useful in magnetic resonance imaging (MRI) programs and other situations where radio frequency issues are a problem.
An active microphone takes advantage of the electromagnetic impact. When a magnet moves through a wire (or coil of wire), it induces a current to flow in the wire. In an active microphone, to move either a magnet or when sound waves photograph the diaphragm, and the movement creates a small current.
In a band microphone, a thin band - generally aluminum, duraluminum, or nanofilm - is visible in a magnetic field. Sound waves move the bands, which change the current through the bands. Ribbon microphones are bidirectional microphones, which means they pick up sound from both sides of the mic.
The RCA PB-31 was the first band microphone. Created in 1931, it changed the audio and broadcast industry as it set new standards for sound assurance. Several microphone microphones make compatible modes, including the BBC-Marconi Type A and ST and C Coles 4038.
As you can see, almost every technology imaginable has been used to convert sound waves into electrical signals. The one thing they have the most resemblance to is the diaphragm, which collects sound waves and makes movement in whatever technology is used to create the signal.