Microphone Technique and Choosing a Vocal Microphone for Live Performance Purposes
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It is rare in this day and age for vocalists, particularly those who sing contemporary genres, to perform without the aid of a microphone, and so it seems relevant for me to give my readers some basic information to get them started toward purchasing and using vocal microphones.
The first sections of this article will cover the features of microphones (e.g. types, pick up patterns, etc.) and some advice on purchasing a microphone. The second part of this article will discuss basic microphone technique for vocalists in a live setting.
Because studio recording is a whole different ball game than live performances, and the specific microphones, as well as the effects, placement (position of the microphone in relation to the vocalist) and techniques are generally chosen by the recording engineer and the producer, I won’t touch upon what happens in a recording studio setting. It’s far too complicated for the scope of both this article and my expertise.
The Best Advice
You must have everything going for you if you hope to compete in the music industry, so choose your microphone wisely. Find a quality microphone that enhances your voice and will enable the sound of your voice to be at optimum quality, in terms of both tone and balance. Anything less (e.g. a cheap microphone that isn’t ideally suited to the quality of your tone) will degrade your voice. The right microphone, when properly used, will capture the most desirable qualities of your voice, producing a much better result than would be achieved with the wrong microphone.
Many sound people and recording engineers believe that vocal microphones are the most important link in the sound system, so buy the best microphone that you can afford. (Don’t get caught up in buying fancy mixing boards while neglecting the quality of the microphone and speakers, because bad sound in translates to bad sound out.)
Buy the right microphone for your voice; the one that is most suited to your particular voice and its unique qualities and range. Go into the music equipment store and try a selection of vocal microphones. When testing each microphone, make sure that the amplifier that you are singing through has its equalizer set flat (i.e., no extra treble, bass, reverb, etc.) so that you can be sure that you are hearing the real differences between each microphone. Listen closely and critically to how your voice sounds through good speakers. If you don’t like the quality of sound that the microphone produces, or if it just doesn’t accentuate your voice’s tone, that particular microphone isn’t the most suitable one for you.
Don’t get drawn into buying a bad microphone for you just because there is a promotion or sale on it that seems too good to pass up. While you may save some money on that particular model, you will likely end up regretting your purchase every time that you sing into that microphone. You will then have to buy another microphone that will do a better job at accentuating the features of your voice, and the money spent on the first microphone will be considered wasted.
In a lot of cases, the places where a singer might gig will have microphones and other standard amplification equipment (e.g., speakers, monitors, etc.) for use by guest performers. (This is generally the case in churches, as well as at music festivals where numerous artists are going to be performing in succession on the same stage.) However, it would be prudent to have a good performance-quality microphone among your assets in the event that the hosting gig site doesn’t have equipment or has poor equipment, or the club’s equipment fails unexpectedly just prior to or during your show. You don’t want to be scurrying around at the last minute to find a microphone to use for your performance, and end up with an unplanned acoustic set and a lot of otherwise avoidable stress. More importantly, though, a microphone that is provided by someone else may not be the best one for your voice, so having your own, carefully-chosen vocal microphone at your disposal may help to give you that leading edge.
For the average singer or band, it is unnecessary to spend a small fortune on microphones that will never leave the rehearsal space. Save your money for quality equipment for live performances or a home recording studio, and instead purchase a rehearsal microphone that will give you reasonably good sound and output at an affordable price.
Good, yet affordable, first vocal microphones such as the Shure SM58 can be purchased for around one hundred dollars. A slightly better quality microphone would be the Sennheiser E835 (at around the same price as the Shure SM58), or the E935 for about sixty to seventy dollars more. These are great vocal and instrument microphones that have a response tailored to the human voice, and many professional singers and musicians use them on stage when gigging.
A good microphone will compliment your voice, but it won't correct it. (Remember the principle of “junk in, junk out”.) It will only capture the quality of sound that exists (i.e., that goes into it) - and even then, the translation process of turning sound into electrical signals and electrical signals into sound is imperfect. No piece of equipment, regardless of how superior its quality, can make you sing better than you do in reality or make a bad voice sound great. If, for instance, you sing out of tune, the microphone will pick up your pitch errors. If you sing in a thin or nasally tone, the microphone will pick up these tonal weaknesses. A microphone cannot be used to overcome or cover up poor singing technique. Improvement must come from you with proper technique and study.
Learn to use the microphone properly. A high quality, correctly chosen device will only produce the desirable result if it is properly used. The manufacturer's data sheet for the microphone is generally the best starting point in determining how to use a specific microphone. Then, comes practice.
Ensure that there is a good manufacturer’s warranty for the microphone, or don’t buy it. Search the internet for customer reviews of the product, and go to the manufacturer’s website for the spec sheets on it. Also make sure that the store has a good return policy.
Finally, purchase the microphone most suited to the physical situation in which you will be using it. For example, if you will be using the microphone in a live setting, don’t purchase one that is intended for use in a recording studio. Many types of microphones have been invented for different purposes and different situations, and how particular microphones translate sound, and the type of sound being captured will help to determine which microphone you will want to purchase.
A microphone is an acoustic-to-electric transducer or sensor that converts sound into an electrical signal. The sensor picks up sound in the form of a human voice and reports it in the form of an electrical or digital signal. Once that signal is read, the audio loudspeaker then converts the electrical voltage variations of the voice pattern – the sound waves - through vibrations of air molecules, into acoustical energy that can be heard by others.
Vocal microphones are designed with the science of acoustical sound in mind. The range of acoustic pressures (e.g., frequencies) that the human ear can detect is very wide, and this is also true for any detectors of sound, such as microphones. The output of the microphone can be filtered to match the sensitivity of the human ear, as well as vocal tones and ranges.
The most common microphone design today employs a thin membrane that vibrates in response to sound pressure. This movement is subsequently translated into an electrical signal.
The most predominant microphones used for live vocal applications are dynamic microphones. Dynamic microphones work on the principle of magnetic induction, converting acoustic energy (sound waves or sound pressure) into an electronic signal using a small diaphragm that moves back and forth. The mechanism is almost exactly the reverse of a speaker, which converts electronic signals into sound.
Dynamic microphones require no external power or battery to run. However, most need some kind of preamp to boost the signal, and you should factor this extra equipment into your shopping and budget.
Dynamic microphones are the most rugged, and are most suitable for live performing, as they can tolerate more abuse than the other types of microphones.
There are two types of dynamic microphones: moving coil and ribbon.
The moving coil type of dynamic microphone is the one most often used today for vocals and instruments. Moving coil microphones use a magnet, a coil wrapped with wire and a diaphragm that sits over the top of both the magnet and the coil. Sound waves cause the diaphragm to move, and in turn, the attached voice coil moves, translating its motion into an electrical signal.
Instead of a coil and diaphragm, a ribbon (or dynamic-ribbon) microphone has a thin metal, corrugated ribbon stretched across the magnetic field. Sound pressure hits the ribbon and moves it across the magnet, which induces voltage. Ribbon microphones are not as commonly used as moving coil microphones today. There are some modern manufacturers that currently make ribbon microphones, but they are primarily regarded as studio microphones.
Condenser Microphones have a much flatter frequency response than dynamic microphones and are usually more expensive. Condenser microphones operate by means of a charge stored by a capacitor. When the diaphragm and back plate are activated by sound, voltage is induced, as with the dynamic, but its voltage is higher and its performance generally more accurate than that of its competitors.
In a condenser microphone, the diaphragm itself is electrically charged, and the variations in the electrical field between the diaphragm and the condenser microphone element, (which is also charged), generate a corresponding electrical signal.
Because of the electrical charge required by the microphone’s elements, condenser microphones require an extra (internal or external) power supply. Either batteries are inserted into the microphone, a permanent charge is retained on the diaphragm or back plate, or more commonly, phantom power from a mixing board is used.
The signal from a condenser microphone is very weak compared to that of a dynamic microphone, so it must be amplified before it gets to the mixing board or studio console. Condenser microphones contain an amplifier that boosts the signal before it leaves the microphone. Condenser microphones are most often used for acoustic instrument mic’ing (e.g., drum overheads, percussion, stringed instruments, etc.) and studio vocals.
Frequency response refers to the way in which a microphone responds to different frequencies. It is a characteristic of all microphones that some frequencies are exaggerated and others are attenuated (reduced). For example, a frequency response that favours high frequencies means that the resulting audio output will sound more trebly than the original sound. A "flat" frequency response means that the microphone is equally sensitive to all frequencies. In this case, no frequencies would be exaggerated or reduced, resulting in a more accurate representation of the original sound. Therefore, it is generally said that a flat frequency response produces the purest audio sound, (although it may not always be desirable).
Phantom power is the supply of power through the ground cable of an XLR cable. This power can be put into the cable either from a mixer, a phantom power box or a battery pack. A mixer might have a button that allows phantom power through the ground cable. A phantom power box is like an intermediate component between a mixer and a mic. It is connected to the mains, and essentially puts a charge on the ground cable. A battery pack does exactly the same thing, but works only with batteries instead of mains power.
Condenser microphones are much more delicate and sensitive microphones than dynamics, and can be easily broken, so they are not considered good candidates for traveling or live mic'ing, except in the hands of a professional sound or recording engineer.
Directionality/Polar Patterns and Pick Up Patterns of Microphones
A microphone's directionality or polar pattern indicates how sensitive it is to sounds arriving at different angles about its central axis. There is a locus of points around the microphone’s head (also called a grille or a capsule) that produces the same signal level output in the microphone if a given sound pressure level is generated from those points. In other words, the microphone’s pickup pattern refers to the way in which a microphone picks up sound from various directions.
Sound pressure refers to the deviation of local pressure from the ambient (average, or equilibrium) pressure that is caused by a sound wave.
Microphones are made with certain applications in mind (e.g., stage use, studio use or field recording use). For that reason, microphones are not always expected to pick up sound universally and from all directions.
There are a few standard pickup patterns: omnidirectional, unidirectional, bidirectional and cardioid. Sometimes, microphone pick up patterns are divided into these four basic types: omnidirectional, cardioid, super-cardioid and hyper-cardioid.
Omnidirectional microphones pick up sound from all directions equally. For this reason, they may not be the right choice for many live applications since they are prone to causing feedback and picking up unwanted background noise. Although an omnidirectional microphone's response is, theoretically, a perfect sphere in three dimensions, this is generally not the case in reality. As with directional microphones, the polar pattern for an omnidirectional microphone is really a function of the wavelength of the frequency being picked up.
The body of the microphone tends to allow in sounds arriving from the rear, causing a slight flattening. This flattening of the polar response increases as the diameter of the microphone, (assuming that it's cylindrical), reaches the wavelength of the frequency in question. Therefore, the smallest diameter microphone will give the best omnidirectional characteristics at high frequencies.
Omnidirectional microphones, unlike cardioids, do not employ resonant cavities as delays, so they can be considered the "purest" microphones in terms of low coloration. In other words, they add very little to the original sound.
Regarding directionality, omnidirectional microphones are pressure transducers, whereas all others are pressure gradient transducers or a combination between the two. Being pressure-sensitive, they can also have a very flat low-frequency response. Pressure-sensitive microphones also respond much less to wind noise than directional microphones, which are velocity-sensitive.
The pressure gradient of air is a measured physical quantity that describes in which direction and at what rate the pressure changes the most rapidly around a particular location – e.g., for a singer’s purposes, around the microphone’s grille – or across a given distance. The pressure gradient results in a net force that is directed from high to low pressure and this force is called the pressure gradient force. The pressure gradient force is responsible for triggering the initial movement of air.
A unidirectional microphone is sensitive to sounds from only one direction. The following three patterns (cardiod, hypercardiod and supercardiod) are commonly used as vocal or speech microphones, since they are good at rejecting sounds from other directions.
The most common unidirectional microphone is a cardioid, (from the Latin for “heart”), microphone, so named because its sensitivity pattern is heart-shaped. The indented top of the heart would be the equivalent of the back of the microphone. In other words, cardioid microphones block the sound from the rear, which gives them better ability to mic a specific area or instrument desired.
A hypercardioid (or shotgun) microphone is similar to the cardioid but has a tighter area of front sensitivity and a tiny lobe of rear sensitivity. When mic’ing instruments that are in close proximity to one another, such as a drum set, a hypercardioid pattern can help to isolate each individual drum or sound source. It can reduce feedback from floor monitors, as well.
A supercardioid microphone is similar to a hypercardioid, except there is more front pickup and less rear pickup, which means that they will block some additional sound from the sides.
Most vocal microphones have either cardioid or hypercardiod pickup patterns. The hypercardioid type is preferable for both live performance and recording due to its high rejection of extraneous sounds around it.
Bidirectional microphones receive sound from both the front and back of the element. Most ribbon microphones have bidirectional pickup patterns.
A wireless microphone is one that does not use a cable. It usually transmits its signal using a small FM or AM radio transmitter to a nearby receiver connected to the sound system. It can also transmit in radiowaves using UHF or VHF frequencies or various digital modulation schemes. Some low cost models use infrared light. Infrared microphones require a direct line of sight between the microphone’s transmitter and the receiver, while costlier radio frequency models do not.
Wireless headset microphones are popular these days, but require a very expensive transmitter and receiver to operate properly. Cheap ones (under $1000 with the microphone) sound cheap. Decent ones can cost anywhere from $1200 to $4500, depending on the quality and brand.