Everyone has an opinion about microphones. They have their favorite mics, set-ups, and rules they believe get the best possible recordings. The truth is, there is no steadfast rule or microphone that gets good results every time. In today’s post, I’m going to give you a brief overview on different microphone characteristics to help you make your own ideas on what microphones you want to use for your projects.
First off, a microphone is a transducer that changes one form of energy into another (sound waves into electrical signals). There are three main types of microphones: dynamic, ribbon, and condenser; each of which makes this conversion through a different process.
Dynamic Microphones use electromagnetic induction by suspending a wire coil in a magnetic field. When sound waves hit the microphones face it displaces the coil in proportion to the amplitude and frequency of the wave. The interaction between the coil and the magnetic field creates an electrical signal that goes through the output and is recorded. Dynamic mics are designed to be able to withstand high SPLs (Sound Pressure Levels) which makes them well suited for snares, toms, and other loud percussive sounds. Dynamic mics also work great on guitar amps and tends to produce a thicker, more rugged sound than condenser mics. They are best used for capturing low and midrange information; the high frequency information isn’t as accurate as with ribbon and condenser mics. Although dynamic mics are not typically used on vocals, there are certainly situations where they can work well.
Ribbon Microphones also use electromagnetic induction; however instead of a coil they use an extremely thin (2 microns) aluminum ribbon. The ribbon is very fragile, and is definitely not suited for high SPLs. The ribbon can also be ruined by phantom power, so be careful to make sure it is not engaged on any channels with a ribbon mic. The ribbon mic has a fast response and is able to accurately track sound waves over the entire frequency spectrum. Ribbons tend to have a slightly darker quality than condenser mics which makes them ideal for recording bright instruments without creating a harsh sound by over-emphasizing the higher frequencies.
Condenser Microphones operate on electrostatic principle; the capsule consists of two plates, one movable, one fixed. Once powered, the plates are charged and reach equilibrium with each other. To oversimplify, when sound waves hit the front plate it is displaced and the capacitance between the two plates changes. This information is sent through the output and recorded. Condenser microphones are the most commonly used microphones are able to capture most instruments accurately. Because of their high sensitivity they are also able to capture quiet or distant sounds better than dynamics. Be careful though, as they are less sturdy than dynamics and can be easily damaged my mishandling and condensation. It is always a good idea to keep condensers boxed up when not in use.
Microphones also vary in their directional response. Omnidirectional mics respond well to sound waves coming from all directions. Cardoid pattern, the most typical pattern, tend to respond best directly in front of the microphone, but also takes waves from the side, diminishing to a null point in the back of the microphone. Bidirectional microphones capture waves in the front and back of the microphone, with null points to the sides at 90 and 270 degrees. When placing directional mics, keep in mind that you can use the null points to block out other instruments and help cut down on bleed when recording multiple instruments at once. Directional microphones (all types except omni) also have what is called a proximity effect which causes a boost in the low end when the mic is placed within a foot of the instrument. This isn’t necessarily a bad thing, but you’ll want to be careful to make sure the sound isn’t too boomy or muddy.
Knowing how the different microphones respond can give you some guidance on how to choose a mic and position it. Don’t be afraid to break the rules though and experiment.