Soundware Guides: Microphones
| In this guide we'll explain the differences between the main types of microphones, and give you some tips for choosing a microphone and getting the most out of it in a recording situation... |
Where do I start?
A good quality microphone is a useful addition to any recording setup, and can make a huge difference to the sound of your recordings. It's important to choose a microphone that's suited to the type of instruments or voices you want to record.
It's also important to look at the way you position your microphones to make sure that you're getting the best out of them. Even the most expensive microphone can be made to sound bad if it's positioned incorrectly, so experimenting with placement can be a great way of improving your recordings.
To connect a microphone to your computer, you'll usually need an audio interface (external sound card) to connect the microphone to. However, there are also increasing numbers of USB microphones on the market - these connect directly to a USB port on your computer, so you don't need any extra hardware to use them.
Dynamic Microphones
Dynamic microphones are the simplest in design, and are the type with which most people are familiar - they're the standard 'karaoke-type' microphones.
A wire coil is attached to a diaphragm, which vibrates when sound waves hit it. A magnet fixed inside the coil causes an electrical current to be created in the wire (because of the “Motor Effect”), which is proportional to the strength and frequency of the sound waves.
A dynamic microphone
Because dynamic microphones are so simple, they’re also very robust which makes them ideal for using live on stage. In the studio this makes them useful for recording very loud sounds, such as guitar amps and drums, that could damage more sensitive microphones.
However, dynamic mics are often not sensitive enough to record quieter, more subtle sounds such as acoustic guitars, classical instruments or vocals.
View our Dynamic Microphones Section for more...
Condenser Microphones
Condenser (sometimes called capacitor) microphones work in a slightly different way to dynamic mics. Instead of a coil and a magnet, a capacitor is made up of two plates with opposing electrical charges (one positively charged, one negative). One of these plates can move and acts as the diaphragm, and one is fixed in place.
The opposing charges create a voltage across the capacitor, which changes depending on how close together the plates are. So, when sound waves hit the diaphragm, it moves and a voltage proportional to the sound waves is created.
Condenser microphones give a much more detailed sound signal than dynamic mics, and are the most commonly used in studio situations for recording acoustic instruments and vocals. However, they are easily damaged and so are not always suitable for recording very loud sounds.
Unlike dynamic microphones, condenser mics also require an electrical current to creat the charge in the capacitor plates, known as 'phantom power'. This is usually supplied by the mixing desk or preamplifier that the microphone is plugged into, although some portable condenser microphones can be powered by batteries.
The size of the diaphragm used in condenser microphones can vary. Large and small diaphragm condensers have different qualities and as such are used for recording different sounds.
Large diaphragm condenser mics are generally more sensitive, but because of this are more fragile. They also “colour” (or reduce the quality) of sound coming “off-axis” (outside their pickup area). They are generally used for solo vocal recording.
View our Large Diaphragm Condenser Microphones Section for more...
Small diaphragm condensers are less sensitive, but are more robust and do not colour off-axis sound as much. They are useful for recording acoustic guitars or classical instruments, and are often used in pairs for ambient recordings of groups of instruments, for example a string quartet or vocal ensemble.
View our Small Diaphragm Condenser Microphones Section for more...
USB Microphones
To connect a standard microphone to your computer, you usually need to use an audio interface (external sound card) to connect the microphone to.
However, there are an increasing number of USB microphones on the market. These connect directly to a USB port on your computer, so no extra hardware is needed.
USB microphones are available in dynamic and condenser types. They can be slightly limiting because you can only use one USB microphone at a time, but can be useful for beginners or simple recording tasks like spoken word recordings. USB microphones often include bundled recording software too, so you can get everything you need to start recording in one package.
View our Small Diaphragm Condenser Microphones Section for more...
Microphone Terminology
Polar Patterns
The polar pattern of a microphone is the area around it where it is able to pick up sounds.
Different polar patterns have different uses – for example, cardioid microphones, which pick up sound coming from one side only, are useful for live work as they reduce the risk of feedback, or for reducing spill between microphones when several musicians are being recorded at once. An omnidirectional microphone, on the other hand, picks up sound from all sides and so would be more useful for capturing room ambience. Some common polar patterns are shown below:
Frequency Response
The frequency response of a microphone tells you how well the microphone picks up different frequencies (or "pitches") of sound. This is useful to know so that you can tell which microphones would be best for recording particular instruments - to record a very low sound like a bass drum, for example, you'd need a microphone that's good at picking up low frequency sounds, but if you're recording a piccolo you'd need a different microphone that could pick up higher frequencies.
Frequency response is usually plotted on a diagram that shows the strength with which the microphone can pick up sounds of different frequencies.
Sometimes the frequency response is also given as a range showing the lowest and highest frequency a microphone can detect, such as “20Hz-20kHz”. Although this does not give as much information as a frequency response diagram, it can give a rough idea of the microphone's sensitivity to different frequencies.
Equivalent Noise Level
No microphone is capable of reproducing a sound perfectly - the components that make up the microphone always distort the sound slightly. The equivalent noise level tells us how much noise the microphone itself adds to a sound (usually as a background hiss or hum).
This is measured in dBA (decibels, weighting method “A”) or in dBA-weighted (a slightly different way of measuring how the ear perceives loudness, which will give readings about 12dBA higher than an unweighted measurement). Generally, the lower the equivalent noise level the better.
Maximum SPL
The maximum SPL (sound pressure level) tells us how loud a sound a microphone can pick up without distorting. A high SPL is important if you want to use the microphone to record loud sounds like drums or electric guitars.
Phantom Power
Condenser microphones need their own power source to provide the electrical charges in the capacitor plates. Some condenser mics will run off batteries, but most require phantom power. This is an additional +48V power supply provided through the microphone lead from the mic input. Many mixers and microphone preamps have phantom power supplies built in, but these are also available separately.
Microphone Technique
No matter what type of microphone you're using, the way that it's positioned can make a huge difference to the results you'll get. The best way to get good microphone placement is to experiment and get to know your microphone's characteristics until you find a placement that you like. However, there are some standard methods of positioning microphones that can be a good starting point.
Close Miking
Close-miking is the most commonly used microphone placement technique in popular music. The idea is to place a microphone very close to each instrument, so that a very dry sound with no ambiance or spill from other instruments is recorded. This gives a sort of 'blank canvas', so that effects can be added later on.
A range of very different sounds can be achieved with close-miking, by varying the position of the microphone or using more than one microphone and blending the different tones they give. This gives the engineer a lot of creative control over the sound of a finished recording.
Ambient Miking
The point in ambient miking is to give the most accurate representation of a performance possible, as though you were standing in the room listening to it. Ambient miking is often used in classical and folk recordings or for live performances.
Microphones are usually placed further back from the instruments, so that the sound of the room is picked up as well as the performance. Ambient recordings are usually recorded in stereo, using two microphones.
Stereo Techniques
There are many placements for a pair of microphones when recording in stereo. Here are a few standard techniques:
Coincident
In the coincident technique, the two microphones are placed one on top of the other, almost touching. The microphones face in towards each other, so that each microphone is pointing to the opposite side of the ensemble being recorded.
Near Coincident
In the near-coincident technique, the microphones are angled away from one another, so that the two microphones are pointing at the left and right edges of the sound source.
ORTF
ORTF stands for "Office de Radiodiffusion-Television Francaise". It is a variant of the near coincident placement used by the French National Broadcasting Organisation, where the microphones are placed exactly 17cm apart and at an angle of 110 degrees to each other.
Spaced Pair
The spaced pair technique uses two microphones placed parallel to one another, pointing directly at the sound source. The space between the microphones can be
If you're unsure about any of the above, or if you're not sure which products would be best for you, please
contact us and we'll be happy to offer friendly, impartial advice and recommendations.
