The topics this week deal with Microphones and we will explore the following focus areas:

TRANSDUCING ELEMENTS | POLAR PATTERNS | SOUND RESPONSE | SUPPORT/ACCESSORIES

FOCUS AREAS IN DEPTH

TRANSDUCING ELEMENTS

POLAR PATTERNS

OVERVIEW SPECIFICS DEMONSTRATION

OVERVIEW

Microphones TRANSDUCING ELEMENTS - Convert acoustical energy into electrical energy that we can then record.  It is important to know what type of element the microphone features to best apply the mic in the studio or on set.

SPECIFICS

Moving Coil - A mic that employs the physical property of magnetic induction, dynamic mics use a moving coil suspended around a magnetic pole surrounded by a magnetic conductor.  As the voice coil moves up and down it generates electrical voltage. These types of mics are generally rugged and can be easily used in the field. Example Shure SM-57/SM-58

Variable Capacitance - Commonly called condensers, these mics use a diaphragm suspended in front of a fixed plate. As the gap between the diaphragm and the plate increases and decreases, voltage is generated.  The mics can be very versatile and are engineered for a wide variety of applications from sensitive high-end studio mics, to slightly more rugged shot-gun style field mics. Example Neumann U87, AKG C414

Ribbon - Another magnetic induction microphone, ribbon mics get their name from a small metal ribbon attached to a fixed magnet.  Voltage is generated as the ribbon is vibrated from a sound wave’s pressure.  Ribbon mics are extremely sensitive and very expensive.  Ribbon mics are excellent for high-end vocal and special application recording, almost always executed in a studio environment. Example RCA 44/77, Royer SF24

DEMONSTRATION

This audio recording tutorial from Lynda.com explains the three different microphones available for recording (dynamic, condenser, and ribbon) and their respective advantages and disadvantages.

OVERVIEW SPECIFICS DEMONSTRATION

OVERVIEW

PolarPatterPOLAR PATTERNS - Directional patterns in space represent how the microphone can “hear” the sound around it.  Polar Pattern diagrams are usually represented in a circular grid with the mic in the center axis.  Each mic will have its own unique shape, based on three basic directional characteristics: Omnidirectional, Bidirectional and Unidirectional.

SPECIFICS

Omnidirectional mics capture sound the all around the mic. Also called nondirectional mics.

Unidirectional mics capture sound from the front only. These directional mics can be broken down into their level of directional characteristics based on their heart-shaped pattern; cardioid, supercardioid and hypercardioid.

Bidirectional mics capture sound from two sides of the mic capsule, typically front and rear. Ribbon transducers are always bidirectional due to the ribbon being open on the front and back of the mic. It is important to note that bidirectional and stereo are not interchangeable terms. Stereo techniques use two mics or capsules to create a stereo image of sound from discrete left and right channels. Stereo techniques will be covered in greater detail in Session 6 - Studio Recording.

DEMONSTRATION

Understanding Mic Polar Pattern Specifications by Shure.

SOUND RESPONSE

SUPPORT/ACCESSORIES

OVERVIEW SPECIFICS DEMONSTRATION

OVERVIEW

SoundResponseSOUND RESPONSE - Each microphone has its own way of capturing sound. The mic’s frequency response will inform the operator if it will accurately capture the desired sound. The sound response can also depend on how well the mic can handle high volume and self-noise.

SPECIFICS

Frequency response characteristics are immediately important to an engineer based on what the source is. For example, some mics have roll-off in the low frequencies that make them more appropriate for mid and high-frequency applications like vocals or cymbals, while others are specifically designed to capture the intense low frequencies from a kick drum.

Max SPL (Sound Pressure Level) tells an engineer how loud a sound can be before it distorts. The higher this number is the better the microphone will handle loud sounds. Dynamic mics are usually superior to other mics due to their general rugged construction at handling higher SPL. Ribbon mics have very low Max SPL ratings and are not intended for capturing loud sounds.

Self Noise is the electrical noise the mic's circuits introduce into the signal chain. Mics with high to signal-to-noise ratios (S/N) are better at controlling the unwanted hiss the electronics produce.

DEMONSTRATION

Matt of 1092 Studios tests some tried and true microphones on a kick drum and sends the results through a frequency analyzer.

OVERVIEW SPECIFICS EXPLORE

OVERVIEW

AccessoriesSUPPORT/ACCESSORIES - Just like controlling noise and reflections in a room, microphones also need support to control unwanted sounds from being recorded. Due to the wide variety of sensitivity, some mics need to be powered or have extra electrical support to have a clean signal.

SPECIFICS

Pre-amps - Boost the signal from the mic. Many high-end mics actually produce a very quiet, delicate sound. The pre-amp is in place to make the sound usable.

Phantom Power - Condenser mics require voltage to charge their plates. This external power supply is called phantom power and is usually rated at 48 volts.

Mounts - To reduce handling noise and other vibrational noise, shock mounts act as suspension systems for the microphone to mechanically isolate the mic.

Filters - Windscreens and pop filters are external devices that are placed or attached externally to the mic to block unwanted wind sounds or plosive sounds from human voices.

SPOTLIGHT

INSIGHTS