Live Sound Microphone Topics:
» Types of microphones
» What Is Impedance?
» Why Do Polar Patterns Matter?
» Which Microphone is Right for Me?
» What to Look For

A microphone is the first link in the audio chain that transmits your voice and music to your audience. With hundreds of models available, it can be a challenge to know which mic is best suited to your needs. This guide will help you sort out the different types of microphones and make an informed choice. For more information, call us at 1-800-222-4700 for assistance from one of our knowledgeable Sales Engineers.

Wired or Wireless?
One of the first choices to make when selecting a microphone is whether to use a wired or wireless mic. There's so much to discuss regarding wireless systems that we've created a dedicated Wireless Microphone Buying Guide to cover the topic. You'll find it here.

Types of microphones

Dynamic Microphone The most common type of microphone found in live music settings is the dynamic mic. In most dynamic mics, a very thin, light, diaphragm moves in response to sound pressure. The diaphragm's motion causes a voice coil that is suspended in a magnetic field to move, generating a small electric current. Generally less expensive than condenser mics (although very high quality dynamics can be quite expensive), dynamics feature quite robust construction and can often handle very high SPLs (Sound Pressure Levels). Because of the mechanical nature of their operation, dynamic mics are sometimes less sensitive to attack transients, and may not reproduce quite the high-frequency "detail" other types of mics can produce. In the recording studio, dynamics are often used on electric guitars, drums, and more. One example of a highly popular dynamic microphone is Shure’s SM58, shown here.

Condenser Microphone Condenser microphones are most often found in recording studios. However, many condenser mics are now being used in live sound environments. The condenser microphone is a very simple mechanical system, with almost no moving parts compared with other microphone designs. It is simply a thin stretched conductive diaphragm held close to a metal disk called a backplate. This arrangement basically produces a capacitor, and is given its electric charge by an external power source. When sound pressure acts on the diaphragm it vibrates slightly in response to the waveform. This causes the capacitance to vary in a like manner, which causes a variance in its output voltage. This voltage variation is the signal output of the microphone. One example of a popular condenser microphone for live use is Neumann’s KMS-105, shown here. Many lavalier mics are condenser types as well.

What Is Impedance?

Most sound systems use low-impedance microphones.
In looking at microphone specifications you will find models described as "low impedance" or "high impedance." Impedance refers to how much a device resists the flow of an AC signal, such as audio, and it's measured in ohms. When referring to microphones, low impedance is less than 600 ohms and high impedance is generally greater than 10,000 ohms.

High-impedance microphones can be built very inexpensively. However, their response deteriorates rapidly as cable lengths increase, with 18-20 feet being the limit to avoid seriously compromised signal. Low impedance microphones can transmit signals for hundreds of feet without appreciable changes in their signal. That's one reason most sound systems are built around low impedance mics.

Why Do Polar Patterns Matter?

Depending on their design and construction, microphones respond to sound coming from different directions with varying degrees of sensitivity. A plot or graph of this response is called a polar pattern. Looking at a mic's polar pattern will tell you how directional it is and how well it will reject sound from certain directions. Most mics fall into one of two categories: unidirectional or omnidirectional.

A unidirectional microphone rejects bleed and prevents feedback.
In general, stage microphones should usually be unidirectional, with a "cardioid" (or supercardioid or hypercardioid) polar pattern ("cardioid" refers to the heart-shaped graph that represents this pattern) to reject "bleed" from other voices and instruments and voices. However, many lavalier mics are omnidirectional so that they can capture a voice evenly while the speaker's head may be turned

Which Microphone is Right for Me?

As always with choosing the right mic for your needs, there are a number of factors to consider, both subjective and objective. You'll probably be using unidirectional microphones in most applications because they're so good at isolating sound sources and avoiding feedback. If you're using stage monitors, you may want the tighter pickup patterns, and consequently better gain-before-feedback, of supercardioid mics. The type of instrument you're miking and the sound you're going for will tell you whether you need the frequency response of a condenser mic or a dynamic mic.

Spoken Word
Popular Choices: Sennheiser EW 122 G2, Shure Beta58A, Audio-Technica ATM27HE
There is no doubt that wireless lavalier microphones have just about become the standard for miking spoken word on stage. From lectures to worship services, the low-profile design and freedom of movement make lavaliers popular choices for many live sound applications. Wireless headset mics are finding favor with singers that need to be able to perform dance moves on stage while singing. If the speaker of performer feels strongly about moving around, wireless is most often a necessity. That's not to say, however, that a reliable wired lectern microphone doesn't have certain advantages. Consider the following:

Vocals (Singing)
Popular Choices: Shure SM58, Sennheiser e 835, Neumann KMS-105
Some top singers use relatively inexpensive dynamic mics such as the Shure SM58, rather than condenser models, because the dynamic mic gives them a warmer, thicker sound and tends to wear better through hundreds of services. On the other hand, a breathy, delicate voice can benefit from the detailed high end of a condenser mic like the Shure KSM9. Wireless headset mics are finding favor with singers that need to be able to perform dance moves on stage while singing. If the speaker of performer feels strongly about moving around, wireless is most often a necessity, but by and large, wired dynamic are still the stage standard for vocals.

Drums
Popular Choices: AKG D 112, Shure SM57, Samson 8Kit, Audio-Technica ATM250
In many live sound systems, optimally, each drum has its own mic. Using microphones with tight polar patterns on toms helps to isolate the sound from each drum. The snare requires a mic that can handle a very high SPL (Sound Pressure Level) so a dynamic mic like the Shure SM57 is usually a good choice. A kick drum needs a good low-frequency mic like the Electro-Voice RE20. The brilliance and high frequencies of cymbals are picked up best by a flat-response condenser mic such as the Samson C02. Several manufacturers make multi-mic drum kits (like the beyerdynamic Opus Drum Pack) that provide all the mics you need.

Another approach to miking drums live is to have a pair of well-placed condensers as overheads and a kick drum mic. This more minimalist approach is great for situations where channel counts are limited, and works particularly well on rock-style music where the drummer's snare and toms tend to be very loud and close-miking often unnecessary. This 3-mic setup can be done with a variety of mics that hit all price points, from a pair of Rode NT5s and an Audix D6 to a dedicated 3-mic kit such as the Earthworks DK25/L.

Guitar
Popular Choices: Shure SM57, Sennheiser e 609 Silver, Audix i5, Shure Beta57A
A typical guitar amp has sound characteristics, believe it or not, similar to the human voice. In most instances, a dynamic vocal or drum mic will do fine. The Shure SM57 or Sennheiser e 609 Silver are popular choices. Dynamic mics can also typically handle high SPLs, which is another reason that dynamic mics fare well on guitar cabinets.

Bass
Popular Choices: AKG D112, Audix D6, Sennheiser MD 421 II, Electro-Voice RE20
Much like a guitar amp, a bass amp produces plenty of volume, and a good large-diaphragm dynamic mic often works well for capturing the wide range of tones a bass can produce without overloading. A good rule of thumb when selecting a mic for a bass cabinet is that if it works well on a kick drum, odds are it will do fine with bass guitar, as well. The AKG D112 provides excellent low-end support with plenty of punch.

In situations where the stage is small and bleed from other amps is an issue, going direct to the mixer can be an option. A direct signal can be sent from a direct out on an amp, a direct box, or an amp emulator.

Horns
Popular Choices: Audix i5, Audio-Technica Pro 35ax
Directional (cardioid) dynamic mics with a smooth, flat response and the ability to handle high SPL, are good choices for horns. The Audix i5 is very effective on horns as well as guitars and drums.

Grand Piano
Popular Choices: AKG C 414 B-XLS, Rode NT5
Two flat-response large- or small-diaphragm condenser microphones are called for here. You might try one, positioned 12 inches above the treble strings and the other above the lower strings. Also, you might try both mics at about 8" from the hammers. A popular choice is the AKG C 414 B-XLS.

Electronic Keyboard
Popular Choices: Sennheiser e 609 Silver, Shure SM57
Since most electronic keyboards can be plugged right into an amplifier, you can follow suggestions for electric guitar - essentially a dynamic microphone such as the Shure SM57.