Microphone Buyer's Guide

Microphone Buyer's Guide

When choosing the right microphone, the first thing to consider is how you will be using the mic. Will you be using it for live performance events or recording sessions? Do you plan to use it for vocals or will you be amplifying an instrument? Buying the wrong mic can have a noticeable impact (and not in a good way) on your sound quality.

Microphones are acoustic-to-electric transducers that convert sounds into electric signals. They have a variety of uses, including phone systems, recorded audio, radios, hearing aids, radio and TV broadcasting and more.

Looking for tips on how best to clean your microphone(s)? Make sure to check out this helpful article from Shure.

• Types of Microphones
• Microphone Connections
• Important Microphone Specs to Consider
• Important Wireless Microphone Specs to Consider

Types of Microphones

• Condenser
• Dynamic
• Ribbon
• Carbon
• Crystal

Condenser microphones

The most common type of microphone you'll find in the studio, condenser mics have a pretty good frequency range. One of the oldest mic designs available, they also have the ability to closely reproduce the speed of an instrument or vocals, referred to as the transient response. For this reason, they're great when recording accuracy and clarity is imperative.

Because of their fragility and sensitivity to loud sounds, condenser microphones are typically used only in the studio, though you might find them in a live set up as drum overheads. Condenser microphones require an external power supply, about 48 volts, whether it's through a mixer or pre amp. Condenser mics are generally more expensive than other microphones; so while shopping for them, don't fall into the trap of buying one that costs on the low end of the spectrum, as they likely won't produce high quality sound.

Dynamic microphones

Dynamic mics are more rugged than condenser microphones. They're able to handle higher sound pressures and the effects of the elements, making them perfect for live performances and outdoor concert settings. They can be used in a studio, but they're better suited for heavy metal and rock vocals than acoustic music, which requires more subtlety and clarity. Dynamic microphones don't need an external power source.

Ribbon microphones

Ribbon microphones utilize a thin, metallic ribbon to produce sounds. The ribbon reverberates from sound pressure to create a pickup. Considered by many to be one of the most natural sounding mics available, ribbon microphones are bidirectional, meaning they pick up sound equally well from either side. They are incredibly fragile, however - even a slight jostle could cause damage. The output is also less than that of, say, a dynamic microphone, so hum rejection and shielding are important to consider. These mics, once commonplace in professional studio settings, have made a comeback during the rise of home recording over the past 30 years.

Carbon microphones

A carbon microphone's design consists of two metal plates separated by carbon granules. One of these plates faces outward, acting like a diaphragm. When hit by sound, the plate pushes the carbon particles together to create audio signals. Though they're extremely cheap and durable, they don't have the best frequency responses, meaning they can't handle the highest highs or lowest lows as well as other mics on the market. This sometimes results in a background hissing noise. If you're interested in recording music, then you should consider a different type of microphone.

Crystal microphones

Crystal microphones use crystal materials to convert sound energy into electrical energy. These mics are generally considered to be low quality, but offer substantially better sound than carbon mics. These are the go-to microphones when low cost is your biggest concern.

Microphone Connections

Once you've picked the type of mic you want, you need to consider how its connected to your sound system. You have two choices: wired or wireless.

Conventional wired microphones use a cable to transmit audio signals to your sound system. These can impede the movement of performers on stage, especially during larger productions. If you require the ability to move around, you might want to consider a wireless microphone. Wireless microphone systems use a transmitter to send these signals through the air to a receiver and through your sound system, making it easier to be mobile.

Important Microphone Specs to Consider

Now that you know the type of microphone you want, and the connectivity that's best for you, there are a number of specs to consider:

• Polar pattern
• Frequency response
• Dynamic range (typical)
• Signal-to-noise ratio
• Maximum input sound level
• Output impedance
• Output connector
• Sensitivity
• Impedance

Microphone specs: polar patterns

Polar pattern, or pickup, refers to a microphone's directionality - essentially how your microphone picks up sounds from different directions. There are several types of polar patterns:

• Bi-directional (or figure eight) Cardioid
• Cardioid
• Omnidirectional
• Supercardioid

Bi-directional microphone polar pattern. Supercardioid microphones have a narrower pickup compared to cardioids and are also resistant to ambient sounds and feedback. Placement is key with them, however, since they offer some pickup at the rear. Proper monitor placement is imperative.

Cardioid microphone polar pattern. Mics with this polar pattern focus on the sound entering the front of the microphone while rejecting sounds from the sides or rear. The visual pattern looks similar to a heart. Cardioid microphones are used for most microphone applications where the desire is to remove any background noise and focus mainly on the sounds within the front cardioid range. Avoid holding these mics too close to the source as they are susceptable to low frequency feedback.

Shotgun microphone polar pattern. Shotgun mics work similar to cardioid mics in that mostly reject sounds from the side, but shotguns allow for a bit more bleed in this area than a traditional cardioid microphone. Additionally, shotgun mics also capture some sound from the rear of the mic so you should expect some environtmental ambience in your recordings if you use these. The main advantage of a shotgun mic is its ability to work effectively at longer distances from the source, though it is important that the source stay within the polar pattern area of the mic or there may be some drop-off in audio.

Omnidirectional microphone polar pattern. Omnidirectional microphones are perfect for capturing the ambience of an entire area. These are excellent for picking up sound from multiple sources, such as a church choir, stage play or tv interviews.

Microphone specs: frequency response

This refers to the way a microphone responds to frequencies over its operating range, exaggerating some and reducing others. Each microphone has its own frequency capabilities, but the two most common types of frequency responses are flat and tailored. Flat consists of all audible frequencies from 20Hz to 20,000 Hz, an incredibly large range. This is best for recording scenarios, where sound needs to be reproduced without alteration. Tailored frequency responses are used when you need to enhance one particular selection of a frequency range, whether it is live vocals or instruments.

Microphone specs: dynamic range

Your microphone's dynamic range refers to the difference between the lowest and highest signals it can produce, measured in decibels. A mic with a moving coil has a range as high as 140 dB. Condenser microphones offer less of a range. It's much easier to overload them.

Microphone specs: signal-to -noise ratio

A microphone's signal-to-noise ratio is the difference between the level of the desired audio signal it intends to record, whether it's speech, music, etc., and the noise level it picks up in the background (such as your AC humming or an airplane flying overhead). So you want a microphone with a high signal recording, but a low noise recording. Average microphones have a signal-to-noise ratio of 60dB or above, while the best will have 100dB or greater.

Microphone specs: maximum input sound pressure level (SPL)

This indicates the highest sound pressure level your mic can handle before distorting the audio signals. An average microphone will see a 0.5% distortion at 1,000 Hz, though you might be able to increase the amount of volume your mic can absorb before distorting it by using an attenuator switch. The use of your microphone will determine what your maximum SPL should be. Heavier rock will require a mic that can withstand a greater volume.

Microphone specs: output connector

There are many different connectors available to connect your microphone to your sound system. The four most common are:

• TRS connectors
• XLR connectors
• Multi-pin circular connectors
• Modular connectors

TRS connectors are the most common ones used by average consumers. Also referred to as the phone plug, they typically come in three sizes: 1/4", 3.5 mm and 2.5 mm. They also are available for mono and stereo configurations, while many other connectors are not.

The 3-pin XLR connector is a standard in the professional realm, while a 4-pin XLR is mostly used on amateur radio microphones. Broadcast professionals sometimes opt to use these connectors as well, because they can use the fourth pin for a push-to-talk circuit controlled by a button on the microphone. This allows them to momentarily mute their sound, in case they have to cough or clear their throat.

Multi-pin circular connectors are screw-on circular connectors for Citizens Band and amateur radio devices. These connectors are available with anywhere from two to eight pins. The problem, however, is there was never an industry standard set for the pin assignments, so they vary from manufacturer to manufacturer, often making them incompatible with other brands.

For more modern radio equipment, you'll want to use a modular connector, though they were originally created to be used with telephones and later computer networking. These connectors also suffer from a lack of industry standards, so they're often incompatible from brand to brand, sometimes even within one brand's models.

Microphone specs: sensitivity

Your microphone's sensitivity rating tells you how much power it will produce for a specific sound it picks up. The higher the sensitivity, the higher the voltage output. It won't need as much amplification as a device with lower sensitivity. Standard microphones can produce a 1,000 Hz tone at an SPL of 94 dB.

Microphone specs: impedance

Measured in ohms, impedance refers to the resistance of a circuit to an alternating current, which in the case of your microphone and sound system is the audio signal being transmitted. Microphone impedance is generally rated as low (less than 600 ohms), medium (600 to 10,000 ohms), or high (above 10,000 ohms), though some microphones have the ability to select between the different ratings. While not the most critical of the specs to consider, it still can have an effect on sound clarity and quality. Low impedance is usually preferable to high impedance mics, as high impedance devices generally don't perform well over longer distance cables.

Important Wireless Microphone Specs to Consider

Wireless microphone systems - and each of their components -- have even more specs to consider:

• RF carrier frequency range
• Operating distance
• Overall frequency response
• Number of simultaneous system

Wireless microphone specs: RF carrier frequency range

RF is an abbreviation for "radio frequency" and is used to refer to the range of electromagnetic sound waves your wireless microphone can transmit through space. They can transmit these radio waves by using UHF (ultra high frequency) or VHF (very high frequencies) frequencies, FM, AM or digitally. UHF systems operate between 470 MHz and 698MHz, where most modern wireless systems fall; while VHF systems are between 150 MHz and 216 MHz. Some wireless mics operate on a single frequency, while others hop across a spectrum of frequencies.

Wireless microphone specs: operating distance

The distance over which the wireless microphone you're using can operate will vary with each device. Some require you to be in view of the receiver at all times, while others will have a longer range. Your average wireless microphone will generally be about 500 feet, though better quality setups for professional live performances can have a longer distance range.

Wireless microphone specs: frequency response

This refers to the way your wireless microphone responds to different frequencies. Each microphone will either exaggerate certain frequencies or reduce them. If you use a mic with a frequency response that favors higher tones, for instance, then the sound it transmits will likely have more treble to it than the original signal. Each microphone will have its own frequency response pattern that can be charted to show you which tones will be exaggerated and which ones reduced. Ideally, you want a microphone that produces a response curve that is as close to flat as possible, as these will treat all frequencies similarly and produce a more concise sound. Sometimes, however, you'll want a tailored response if you have any specific sounds that require emphasis.

Wireless microphone specs: number of simultaneous systems

As they've become more popular over the years, it's not uncommon to see several wireless systems used at once in one location. However, the more systems you have operating at the same time, the more susceptible they are to signal interference and unreliable sound. In addition to interference, you might also see a reduced range and unexpected signal losses.

The most common cause of this interference is using multiple systems that are incompatible or have too similar a frequency range, meaning they're competing for the same frequencies while transmitting audio signals. Also, you need to pay close attention to how you set up each system. If their physical proximity is too close or they're touching, radio signals from one unit might work their way into the signals from another.

Wireless Microphone Transmitter Specs to Consider

• Battery type/approx. life
• Number of channels
• Mute switch/Level control

Battery type

All wireless microphone transmitters - and some receivers - rely on batteries as a power source. The type of battery used varies from system to system, the most common being alkaline, zinc carbon, lithium, heavy duty rechargeable nickel-cadmium (NiCad) or rechargeable nickel metal hydrid (Ni-MH). The battery life varies for each, from about an hour or so for zinc-carbon batteries to 25 hours and up for lithium. Make sure you put in a fresh battery before every use, because a weak power source could cause sound dropouts. Also, if you choose to use a NiCad battery, remember that the 7.2 volt version most commonly available could lead to poor sound performance. You'll want to use 8.4 volt NiCad batteries.

Number of channels

You can purchase an inexpensive wireless mic system with just one channel and frequency, but better systems will offer more channel and frequency options. If you have only one channel to broadcast your audio signals, it could be overwhelmed by other, stronger signals nearby, resulting in degraded sound quality. This is often a cause of annoying static and popping sounds. Having the option of switching channels reduces the likelihood of sound interference.

Mute switch/level control

Mute switches and level controls can be a musician or presenter's best friend. Mute buttons, or push-to-talk button, are used with mics that utilize a 4-pin connector. This allows you to quickly mute and unmute your audio so that you don't project any unwanted signals to your audience, like coughing, clearing your throat or talking backstage. Sometimes the switch is on the microphone itself or you can purchase an optional remote mute.

Your wireless mic will also have separate volume controls for you to adjust it for precise vocal balancing. Often, your receiver will feature additional level controls to achieve the best sound.

Wireless Microphone Receiver Specs to Consider

• Carrier frequency range
• Antennas
• THD
• Audio sampling rate
• Modulation
• Compression
• Latency
• Encryption
• Receiver type
• Equalization (EQ)
• PC interface

Carrier frequency range

Carrier sound waves, or signals, are modified by an input signal to transmit information. Generally, the carrier wave has a much higher frequency than the input. Carrier waves are used to transmit radio signals or to make it easier for several carriers with different frequencies to share the same transmission system. They can transmit these radio waves by using UHF (ultra high frequency) or VHF (very high frequencies) frequencies, FM, AM or digitally. UHF systems operate between 470 MHz and 698 MHz, while VHF systems are between 150 MHz and 216 MHz. Most wireless systems, because of their large bandwidth, utilize either UHF or VHF.

Carrier frequency ranges vary from system to system, but the wider the range, the better the sound, and also the less you have to worry about interference from other signals. You need to make sure your receiver is capable of accepting the range of your transmission's carrier, while having the ability to deflect the majority of others.

Antennas

Your receiver will come with at least one whip antenna, either permanently attached to your device or plugging into it. These are best used with an installation with reliable signals. While whip antennas are effective, affordable and convenient to use, there are times when you'll need to use a remote antenna. These come in handy when the location of your receiver doesn't have good reception. These remote antennas will connect to your receiver via a coaxial cable - any other cable will result in sound loss. And if you have the right mounting materials, you can sometimes use your whip antennas remotely.

Audio sampling rate

Measured in Hertz, audio sampling refers to the rate at which your wireless microphone captures audio data and sends it to the receiver. The higher the rate, the better the sound. On the low end, your mic will have a rate around 8,000 Hz. It's adequate for your performance or recording, but lacks sibilance, which means your "s" can sound like an "f". Professional, CD-quality encrypted wireless mics will have a rate up to 44,100 Hz.

Modulation

There are two kinds of carrier wave modulation: frequency and amplitude. Frequency modulation (FM) varies the frequency of a signal in order to convey information over a carrier wave. With amplitude modulation (AM), however, the carrier's amplitude is varied and modified while the frequency remains constant. Nearly all wireless mics utilize FM modulation and require a large bandwidth, approximately 200 kHz. Because of the size of the bandwidth, wireless microphone systems typically operate with UHF or VHF systems, which have large carrier frequency ranges.

Compression

Compression is used in digital wireless microphones to reduce the RF bandwidth used to transmit it, which is often high with wireless systems. Without compressing a digital audio signal, such a large RF bandwidth could have a negative effect on your sound's resolution, dynamic range and audio bandwidth. It's also helpful for dealing with very dynamic performances so that the softest sound can still be heard without loud sounds distorting.

Latency

Latency is a fancy way of referring to your wireless microphone's digital delay, which can be a disadvantage while performing or recording. Still, a minor delay from your wireless mic likely won't be noticeable in the sound you're producing until it's combined with a delay from other digital devices in your systems. Analog wireless mics have close to zero delay.

Security and Encryption

Encryption technology helps ensure signal transmission security and reliability in digital wireless systems. It helps prevent unauthorized listening of your audio recordings and is critical for high security scenarios and corporate users.

Receiver Types and Signal Drops

There are several receiver types to choose for your wireless mic system. Antenna diversity - or space diversity - are wireless receivers that utilize two or more antennas. These are perfect for urban and indoor settings, where there isn't usually a clear line of sight between the transmitter and the receiver. True Diversity receivers feature two radio modules in addition to the two antennas, while Diversity receivers have just one module. You'll get higher quality sound from a True Diversity receiver. There are also non-diversity receivers, which operate with only one antenna and are prone to fadeouts, sound drop-offs and a generally lower quality transmission of audio signals.

Think about receiver types as you would your car radio or dual band wireless router. If you only have one option to choose and there's a lot of activity, your signal will likely suffer. The best options are units that offer the ability to dial in a channel or offer auto-switching.

Equalization (EQ)

Your receiver should come with an equalizer control. Equalization, or EQ, comes in handy when enhancing vocals. For instance, turn down the low frequency sounds to reduce handling noises, breath pops and other background sounds that are picked up, while adjusting the higher frequencies can increase vocal clarity for mics hidden by hair or clothing. You can even enhance the mid-range sounds for clearer speech. But overusing this tool can actually have a detrimental effect on your sound, so use it wisely.

PC interface

While you can't just plug in a standard mic to your computer, you can get an audio interace that allows you to connect one, or multiple inputs which are then converted into an electronic signal and sent to your computer via a USB or firewire cable. This is especially useful if you're recording a performance or speech or looking to turn your PC into a wireless studio, as it allows you to easily manipulate the sounds. Note that depending on the type of interface you choose, you may need to use a microphone preamp to ensure a good quality signal.