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Microphone types

    Dynamic Microphones

 (Shure SM58LC Dynamic Microphone)

Dynamic microphones are considered to be robust and reliable microphones. The Shure SM57 dynamic microphone is an industry standard, and for good reason.

Dynamic microphones use what is called a cardioid polar pattern, or unidirectional pattern.

A cardioid polar pattern means that the microphone picks up sound from the direction you point it in and cancels any sound coming from behind.

Combined with a moving coil diaphragm, this makes them good for picking up especially loud sounds that come from one direction, such as drums or amplifier speakers, dynamic microphones are very versatile tools for sound production. 

      Condenser Microphones

(Rode NT1 Signature Series Condenser Microphone)

Condenser mics work by using a capacitor (or condenser) to convert acoustic vibrations into an electrical current instead of a moving coil.

That means they need a power source like 48V phantom power to operate. It also means that they’re much more sensitive than dynamic mics or ribbon mics and output a louder signal.

Their sensitivity makes them ideal for quiet or extremely dynamic sources, such as vocals and acoustic instruments, or anything that needs to capture higher frequencies.

Condenser mics can also offer multiple polar patterns including cardioid, bidirectional (capturing sound front and back while cancelling noise from either side), or omnidirectional (capturing sound from all directions).

Ribbon Microphone

(AEA R44 Series - Ribbon Microphone)

Ribbon microphones are highly sensitive (and fragile) microphones. While similar in some regards to dynamic microphones, they are designed differently; the ribbon design includes an extended rectangular diaphragm made of thin aluminium with magnets at either end.

Vibrations caused by sound waves create an electrical charge. Most ribbon mics feature a bidirectional polar pattern, which means they are best used in acoustically-treated spaces.

These microphones were the standard in the 50s and 60s, and were used on vocals and stringed instruments.

• Carbon microphone - also called "button microphones" and commonly found in old landline telephones, these microphones uses thin metal plates and granulated carbon to transmit audio signals into electricity.
• Piezoelectric microphone - also called crystal or piezo microphones, these use piezoelectricity - where some materials produce voltage when pressure is subjected - to convert audio frequencies into electric signals. For example, potassium sodium tartrate is a piezoelectric crystal that works as a transducer, both as a microphone and as a slimline loudspeaker component.
• Fibre-optic microphone - fibre-optic microphones convert acoustic waves into electrical signals by sensing changes in light intensity, instead of sensing changes in capacitance or magnetic fields as with conventional microphones. These microphones are used in areas where electrical or magnetic interference could cause issues, such as inside industrial turbines or in magnetic resonance imaging (MRI) environments.
• Laser microphone - most often used in surveillance contexts, a laser microphone uses a laser beam to detect audio vibrations from reflective surfaces such as windows, which are then translated into an audio signal.
• Lavalier microphones - lavalier microphones (also known as a lav, lapel mic, clip mic, body mic, collar mic, neck mic or personal mic) are small microphone used for television, theatre, and public speaking environments to allow hands-free operation.
• Shotgun microphones - Shotgun microphones are highly directional, which means that they can pick up sound from a specific direction while filtering out background noise.  They are frequently used in film and TV production.
• Speaker - the basic principles by which dynamic microphones operate are the same for speakers - a coil of wire in a permanent magnetic field. Large speakers can be used to record the very low frequencies of bass drums, bass guitar cabinets, and other instruments with a lot of low-end power and energy.

Connections

The most common connectors used by microphones are:

• Male XLR connector (three-pin plug) on professional microphones.
• 1⁄4 inch phone connector on less expensive musician's microphones, using an unbalanced 1⁄4 in (6.35 mm) TS (tip and sleeve) phone connector.
• 3.5 mm (sometimes referred to as 1⁄8 inch mini) TRS (tip, ring and sleeve) stereo (also available as TS mono) mini phone plug on prosumer camera, recorder and computer microphones.
• USB allows direct connection to PCs. Electronics in these microphones powered over the USB connection performs preamplification and ADC before the digital audio data is transferred via the USB interface.
• Some microphones use other connectors, such as a 5-pin XLR, or mini XLR for connection to portable equipment. Some lavalier microphones use a proprietary connector for connection to a wireless transmitter, such as a radio pack.

Microphone Polar Patterns

Polar patterns are closely linked with microphones and affect how your mic’s capsule picks up sound.At a basic level, a polar pattern is the term used to describe the directionality of a mic. They outline just how sensitive your mic is to any incoming sound waves that are delivered from different angles/directions. It’s sometimes also referred to as a pickup pattern. 

Cardioid Polar Patterns

• The most common directional polar pattern.
• Most sensitive from the front.
• Least sensitive from the back. Reduced pick up from the sides.
• Effectively isolates the mic from annoying room/ambient sound.
• Increased resistance to feedback (in comparison to omnidirectional microphones).
• Excellent for loud live environments, or when you need to highlight one sound source – for example, a vocal.
• Two cardioid mics positioned at a 90 degree angle to each other creates the popular X/Y stereo technique. This delivers dedicated left and right recording of your source.

Supercardioid Polar Pattern

• Narrower direction of pickup (in comparison to cardioid microphones) from the front.
• Enhanced rejection of unwanted background sound.
• Very dry signal.
• Smaller amount of pickup at the back and sides (when in close proximity).
• Extremely resistant to feedback. Delivers extremely high gain before feedback.
• Perfect for isolating an individual source in a loud live environment.

Hypercardioid Polar Pattern

• Even narrower direction of pickup (in comparison to supercardioid microphones) from the front.
• Even better rejection of unwanted background noise.
• Small amount of pickup at the rear and sides.
• Equally good at isolating a single source in noisy live environments.
• The most resistant to feedback.

Omnidirectional Polar Pattern

• Equally sensitive from a 360 degree angle. Captures sound evenly from every direction.
• Doesn’t have to be pointed in one specific direction.
• Cannot be aimed away from unwanted sound sources, meaning less headroom for feedback.
• Delivers the flattest frequency response and best bass response.
• Least sensitive to both wind sounds and handling noise.
• Perfect for studio recording. Not very suitable for live shows.
• Ideal for capturing acoustic instruments or wide sound sources (like a choir or orchestra etc).

Bidirectional (Figure-of-Eight) Polar Pattern

• Captures an equal amount of sound from the front and back of the mic.
• Doesn’t capture any sound from the sides. Boasts the highest side rejection of every polar pattern.
• Common among larger diaphragm and ribbon mics.
• Effectively captures your source, as well as the natural characteristics of your space.
• Used for both mid side stereo and Blumlein recording techniques.
• Least bass response.
• Most sensitive to both handling and wind noise.

Adapted from the Microphone Theory Libguide from State Library Victoria.

Polar Patterns taken from Andertons. 

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