Transcript Microphones The Basics

The microphone is
your primary
tool in the sound
chain from sound
source to audio
storage medium.
Factors when capturing a
sound with a microphone:
 microphones location in relation to
the sound source
 the acoustic environment in which
we choose to record the sound
source
Types of Microphones
There are three main types of
microphones:
 1) Dynamic/Moving Coil
 2) Ribbon
 3) Condenser/Capacitor
1) Dynamic/Moving Coil microphones
 They operate on a magnetic principle : movement of a
copper coil around a magnet causes a changing flow of
electrons that represent the sound wave.
In dynamic microphones a physical cone acts
like a lens to concentrate the incoming sound
waves. The concentrated energy of these
sound waves moves the cone and its attached
coil of wire back and forth inside a magnetic
field. The magnetic field induces electricity to
flow through the wire to produce an electrical
signal which is the microphone's output.
The electrical signal is analogous to the
original sound wave: the voltage and current
are proportional to the original sound.
Dynamic/Moving Coil microphones
Advantages:
 durable and can withstand a lot of volume before
they distort (within their own circuitry).
 they don’t require phantom power to operate.
 colours the sound in range between 5-10khz, this
adds clarity, presence and understandability to
many vocal and instrument sounds.
 doesn’t feedback as easily as other mics
Dynamic/Moving Coil microphones
typical uses:
 mostly live situations, but they are also used a lot in
the studio.
 close mic applications (1-12 inches)
 snare drums, guitar amplifiers, kick drum, vocals and
any instrument that can play loud.
Dynamic/Moving Coil microphones
disadvantage:
These microphones often miss the
many subtle nuances of sounds
because it takes a lot of sound
pressure to move the coil.
2) Ribbon microphones
 a metallic ribbon is suspended between two poles of a
magnet. Sound waves vibrate the metallic ribbon which
causes a varying flow of electrons to the different poles of
the magnet.
Sound waves cause the foil to vibrate, producing
fluctuations in the electrical current, creating the
audio signal.
This extremely sensitive configuration picks up a
wide range of frequencies and produces an
extraordinarily rich representation of the original
sound. The trade off for this sensitivity is the
delicacy of the mechanism. These ribbon
microphones are also sensitive to physical impacts
and therefore are not considered portable and can
be easily damaged by power overdrive.
Ribbon microphones
advantages:
 This extremely sensitive configuration picks up a
wide range of frequencies and produces an
extraordinarily rich representation of the original
sound.
 These microphones capture a warmer and smoother
sound than dynamic/moving coil microphones.
 Don’t feedback much in live situations.
 Don’t require phantom power to operate.
Ribbon microphones
typical uses:
 Typically used in the studio because they are
fragile
 Used in close mic applications (1-12 inches)
 Often used for acoustic guitars. Also work well
for vocals.
Ribbon microphones
disadvantages:
 colours the sound by adding a high
frequency edge
 fragile
 will only pick up sounds that are very
close.
3) Condenser/Capacitor
microphones
A charged electrical current is applied to a metal-coated
piece of plastic. the coating vibrates sympathetically in
response to a sound wave because it is very thin.
The metal-coated piece of plastic is positioned close to a
piece of metallic alloy.
The changes in the space
between the surfaces create
a changing discharge of
electrical current.
It makes an electrical
version of acoustic energy
from the sound source.
Condenser/Capacitor microphones
advantages:
 they respond to fast attacks and transients more
precisely than other mics and add little tonal
colouration
 they can be used to record sounds from a greater
distance and capture a broader range of
frequencies
 big advantage: these mics record a sound while
capturing natural ambience of a room.
Condenser/Capacitor microphones
typical uses:
 recording studios
 can be used to record almost any sound…except very
loud ones (ex. Kick drum)
 extremely effective with quiet sounds
 the perfect choice for capturing room ambience.
 almost always used for vocals , acoustic guitars and
drum overheads.
Condenser/Capacitor microphones
disadvantages:
 fairly fragile
 feedback too easily in a live environment
(although some have low frequency roll off
switches to help alleviate feedback
frequencies)
 require phantom power to operate
Microphone Pickup Patterns:
There are three main types of patterns:
 1) Cardioid (unidirectional)
 2) Bi-directional (figure-8)
 3) Omnidirectional (boundary)
Unidirectional or Cardioid Pickup Patterns
They pick up sound primarily from one direction - the front of the
microphone.
This allows for the isolation of the signal source from other
performance elements or background noise.
The cardioid pickup pattern
resembles the shape of a human
heart, hence the name, cardioid.
You point the mic towards the
sound you want to record and
away from the source you don’t
want to record.
Bidirectional or Figure 8 Pickup Patterns
The bidirectional or figure 8 pickup pattern is equally sensitive on
the two opposing faces of the microphone which correspond to
the front and rear of the diaphragm, while rejecting sounds from
the sides.
Very good for recording two voices or
voice and instrument on the same
track.
Positioning is very important to get the
correct blend and balance of the two
sounds.
Omnidirectional or Boundary Pickup
Patterns
The omnidirectional pickup pattern collects sounds equally well
from all directions and will deliver the most accurate
representation of a total environment (usually condenser mics).
They capture room resonance along
with the source, thereby yielding a
much more open sound than that of
the focused cardioid microphone.
A major drawback to omnidirectional
mics is their sensitivity to feedback.
Again placement is a key concern.
Conclusion
 Effective sound miking requires lots of
experimentation.
 Most home studios should have at least
one good moving coil and one good
condenser mic.