Recording Sound - Microphone Choice [Part 1]

Recording Sound - Microphone Choice [Part 1]

So you want to record something. Where do you start? As you will already know, the process all starts with a sound occurring and one or several microphones picking up that sound. However, it isn't as simple as having any old microphone; there are many different types for lots of different applications. The choice of microphone you make can have a huge effect on how a sound records. In this post, I’ll go over the different microphones that are available and tips to choosing the right one for your sound.

Before I go into specifics, a little education. Most commonly, there are 2 types of microphone: Dynamic and Condenser. Each of these types bring their own uses, depending on what you’re recording:

Dynamic Microphone

Dynamic: Most common in music production and live performance, dynamic microphones use a magnet (c) and a coil (b) to pick up the sound. The way in which this is achieved is by having a diaphragm (a) attached to the coil, which surrounds the magnet. As sound waves hit the diaphragm, the coil moves back and forth over the magnet, creating a small voltage. This current is the sent down the cable (d) and converted to a sound signal used by the recording interface.

As this setup involves a magnet and coil, the movement is restricted and therefore only allows a certain dynamic range, which in turn distorts the frequency response. All be it, this is not so much a bad thing. In fact, these features are more often than not useful, which makes them very popular for recording drums, guitar amps and live vocals (the restriction allows less spill to occur from guitar and drums).

A good example of a Dynamic microphone is the SM57. This microphone is perfect for recording a snare drum, as the capsule can handle the high volumes, as well as the complimentary frequency response (right) which is boosted at around 6-7kHz, giving a nice zing to the sound. However, the response dives at approximately 15kHz, meaning the airy frequencies of a vocal or cymbals on a drum kit are not represented. This is where the condenser microphone is brought into use.

Condenser: What makes this microphone type stand out against the others is it's sensitivity. It's able to pick up and therefore represent higher frequencies much more accurately. The way in which it does this is by removing the magnet all together and instead having 2 plates (a+b) with a voltage between them. One of the plates is used as the diaphragm (a). When this plate moves, the voltage between each plates varies, which in turn gives a variable signal that can be used to convert to a sound signal.

As the voltage created between these plates is minute, an input voltage (c) is needed to boost the signal (regulated with a resistor (d)). Generally, you'll see this extra voltage boost on an interface or mixing desk as Phantom Power, or 48v for short. However, some microphones have the ability to use a small battery inside the microphone to provide this.

AKG C414 Frequency Response [source:recordinghacks.com]

A good example of a Condenser microphone is the AKG C414. This particular microphone is a staple in any professional studio, which provides recording for anything from vocals to drum cymbals, foley for a film sound track, brass instruments, guitar and bass amplifiers, acoustic guitars... the list goes on. As you can see from the frequency response, the higher end isn't dipped at all; in fact, it's provided with a lift to encourage those airy frequencies that a dynamic microphone would otherwise lose out on.

There are many more types of microphone that are used throughout the sound industry, including Ribbon, Electrostatic, Fibreoptic and so on. However, as I won't have access to these other types (purely down to budget), I won't be covering them in these first batch of posts. Hopefully in the future when I do get my hands on them (especially the Ribbon mics), I'll have a good go over with them and the advantages they provide.

Recording Types - Conclusion: The above explains (for the most part) how these types of microphones work and a couple of example of what they can be used for. In the next post, I'll go into more detail of how each microphone type can have a wide variety of shapes and sizes, as well as the varying polar patterns at which sound is recorded relative to the microphone.

Thanks for reading!

Alex.