Used Wired Microphone Buying Guide

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Used Wired Microphone Buying Guide

A microphone is a device that converts an acoustic sound signal into an electrical signal. This electrical signal can then be recorded or amplified for broadcasting, communication and recording purposes. Microphones may use a number of different technologies to facilitate the acoustic-to-electric conversion process, including electromagnetic induction, piezoelectric generation, etc.

About Wired Microphones

The invention of the microphone was a seminal event in the history of recorded sound. It allowed the user to manipulate and work with sound in ways that had not been possible before. The fundamentals of a microphone have remained largely unchanged over the last century. It consists of a transducer or sensor that detects acoustic audio signals and converts them into electrical impulses through a variety of methods such as piezoelectric generation, capacitance change, etc. (covered below). The electrical signal thus generated can be manipulated into any number of ways. Many microphones sold today can also convert an analogue acoustic signal into a digital signal. Some microphones also include a radio transmitter to allow for wireless transmission of the generated electrical signal.

Buying a Used Wired Microphone

Wired microphones vary greatly in price, quality, underlying technology, and capabilities. Different microphones are suitable for performing different tasks. Buying a used microphone is a matter of matching the purpose to the appropriate device. Recording microphones are generally different from broadcasting and communication microphones. These broad categories can be further divided into sub-divisions based on specific, narrow purpose. For instance, there are different types of recording microphones for capturing voice, guitar, drums or bass.
Wired microphones are durable devices with very few mechanical moving parts. This gives them a long functional life depending on the quality of construction materials. Used wired microphones will usually perform as well as their brand new counterparts as long as they are well maintained. Since quality new microphones can cost several thousand pounds, buying used microphones comes highly recommended.

Used Wired Microphone Power

A microphone can be active or passive, depending on whether it uses external power or not. Microphones that employ external power are defined as active, while those that work entirely on the current produced through sound waves are called passive. These can be seen below:

Active

An active microphone requires constant electric supply from an external source to work. This may be provided through batteries, or more frequently, through phantom power from a mixer. Active microphones produce a louder, more accurate sound. Example: Condenser and electret microphone.

Passive

A microphone that can work without any additional power is defined as a passive microphone. These can produce the electric current through the sound waves alone. The result is fairly accurate sound with low latency. Example: Dynamic and ribbon microphone.

Used Wired Microphone Transducer Types

The transducer is the part of the microphone responsible for converting an acoustic signal into an electrical impulse. Microphones are typically categorised according to the type of transducer used. Transducers can vary greatly in performance and price, and can be broadly categorised as follows:

Dynamic

A dynamic microphone consists of a thin plastic diaphragm attached to a coil of wire suspended between two magnets. Sound waves striking the diaphragm set it into motion, causing the coil of wire to start moving between the magnets, producing an electric signal through electromagnetic induction. This electric current can be later used for broadcast and recording purposes. Dynamic microphones are affordable, robust, and are suited for live performances.

Condenser

A condenser microphone consists of an externally powered capacitor connected to a diaphragm. Sound waves striking the diaphragm cause the capacitor to change capacitance, producing an electric current. The modulation of the diaphragm in this manner produces a high-fidelity, accurate signal. Condenser microphones are used for recording purposes where quality is of key importance.

Electret

An electret microphone is made up of diaphragm connected to permanently charged electret material. When sound waves strike the diaphragm, the charge on the electret material changes, producing an electric signal. Electret microphones are robust, affordable and easy to manufacture. They are the most common microphones in use in the world and are found in cell phones, laptops, and even recording studios.

Carbon

The first microphones ever invented were carbon microphones. These utilise a capsule of carbon suspended between two metal plates. When sound waves hit one of the plates (diaphragm), it causes a change in the electrical resistance of the carbon granules, creating an electric charge. This is the source of the audio signal. Carbon microphones produce a low fidelity, muffled sound and are used only for special effects purposes.

Ribbon

Ribbon microphones work on the same principle as dynamic microphones: electromagnetic induction. Instead of a coil, a thin ribbon of aluminum connected to the microphone output is suspended between two magnets. Sound striking this ribbon causes it to move, creating an electric current. They have a large dynamic range and are typically used to record percussion instruments such as drums.

Piezoelectric

Certain substances such as potassium sodium tartarate produce an electric current when subjected to pressure. This phenomenon is called 'piezoelectricity' and is used in piezoelectric microphones. When the piezoelectric substance in the microphone is placed under pressure, an electric current is produced. These are typically used in touch-sensitive settings such as recording drums or acoustic guitar.

MEMS or Silicon

In these microphones, a diaphragm is etched directly onto a silicon chip. The diaphragm is pressure sensitive and moves when struck with sound waves, producing an electric current in the chip. The chip usually also has an analogue-to-digital converter embedded which makes recording and broadcast of sound possible. Silicon microphones find use in digital recording studios and broadcast systems.

USB

A USB microphone has a capacitor connected to a diaphragm. Sound waves striking the capacitor create an electric current by changing the capacitor's capacitance. USB microphones also have a pre-amplifier and analogue-to-digital converter built in, enabling direct digital recording and broadcast. These are used in podcasting and recording on digital recorders.

Used Wired Microphone Diaphragm Sizes

The diaphragm is the modulating instrument in any microphone that vibrates in sync with the sound waves. The size of the diaphragm affects the quality and loudness of recorded/broadcasted sound. Different diaphragm sizes may be used for different purposes to create the desired sound. Broadly speaking, diaphragms may be divided into two categories based on their size:

Large

3/4 inches

Mics with large diaphragms produce a big sound as they have more surface area to capture sound. As a downside, large diaphragms are not as accurate. These are typically used to capture vocals in recording studios.

Small

Smaller than 5/8 inches

Smaller diaphragms suffer from a lack of character and volume, but make up for it with highly accurate sound reproduction. They are usually used to capture high frequency sounds such as violin and guitar.

Used Wired Microphone Polar Patterns

The polar or pickup pattern of a microphone refers to its sensitivity to sounds coming from different directions. The pickup pattern is an important consideration in selecting microphones as it can affect accuracy and fidelity. Wired microphones with unidirectional polarity (i.e. those that pickup sound from a single direction) may be useful for recording high-fidelity, accurate sound in studio settings, while omnidirectional mics may be more suitable for general purpose recording and broadcast. The polar patterns of wired microphones can be of the following types:

Omnidirectional

Theoretically, the polar pattern of an omnidirectional microphone is perfectly spherical and picks up sound equally from all directions. In practice, no polar pattern is perfectly spherical, which causes a flattening of sound coming from the rear. Consequently, all omnidirectional microphones are made with as small diaphragms as possible. These can be identified by their round end and are used to record multiple instruments/voices. They are also cheap to manufacture and easy to use.

Unidirectional or Cardioid

As per the name, unidirectional microphones pick up sound from a single direction. In practice, these microphones pick up sound coming directly from the front, which makes them very useful for high-fidelity recording where a particular instrument/frequency has to be emphasised.

Hyper/Super Cardioid

Microphones that are even more directionally sensitive than cardioid mics are called super or hyper cardioid. They can pick up only a selective range of frequency coming directly from the front. Hyper cardioid microphones are used in recording studios where a specific instrument has to be isolated.

Bi-Directional

Bi-directional microphones are equally sensitive to sound coming from both the rear and front. Sound coming from the sides, on the other hand, is muted out. These are used in situations where sound needs to be recorded from two opposite sources, such as an interview.

Shotgun

Shotgun microphones are the most directional of all microphones. All sounds coming from the rear and sides are muted out and a narrow band of frequencies coming from the front are isolated. Shotgun microphones are very useful when ambience noise needs to be muted, such as in stadiums and film sets.

Used Wired Microphone Form Factors

Microphones are used in a variety of settings, from recording professional audio in a studio to broadcasting sound over radio. Wired microphones are usually designed in a variety of form factors to fit certain application requirements. These form factors can be broadly categorised as:

Lavalier

Lavalier microphones are extremely small and meant for hands-free operation. They can be easily clipped onto clothes and are usually used in TV interviews or live shows.

Contact

Contact microphones are usually piezoelectric in nature and pick up subtle vibrations on a surface. These are used to record drums or acoustic guitar in recording settings.

Parabolic

Parabolic microphones collect sound waves on a parabolic reflector and focus them onto a microphone. These are usually used in espionage and eavesdropping.

Noise-Cancelling

Noise cancelling microphones mute ambient noise by picking up sound from only a particular direction. Most noise-cancelling microphones have shotgun or hyper cardioid polar patterns.

Gooseneck

A gooseneck microphone is a standard microphone attached to a flexible cord called a 'gooseneck'. These are usually used for recording or communication purposes on computers.

Buying Used Wired Microphones on eBay

Wired microphones tend to be highly durable and can work well for years with proper maintenance. Buying used microphones is highly recommended as it can save a significant amount of money with almost no perceptible difference in quality. eBay has a large selection of affordable priced used wired microphones. To buy used wired microphones on eBay, go to the eBay homepage and search for 'used microphones' in the Pro-Audio Equipment category. The search results must first be narrowed by condition and connectivity – used and wired – from the left selection pane. From the resultant searches, it is possible to pick microphones by type (dynamic microphones, condenser microphones, ribbon microphones, etc.), by brand, and by pickup pattern (Cardioid, omnidirectional, shotgun). Searches can also be filtered according to form factor: handheld, lavalier, headset, etc.

Conclusion

Wired microphones vary according to underlying technology, form factor, and pickup pattern. The performance of microphones differs according to above parameters. Certain types of wired microphones are better suited for recording, while others perform better in broadcasting. Selecting a used wired microphone is a matter of picking the right mic for the right purpose. As microphones tend to be expensive, buying used wired microphones from eBay is highly recommended.

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