Microphones (foun.dig.med)

Question 1

Open back vs closed back headphones

Answer 1

OPEN BACK = You can listen to your sound and the sound of your environment. More natural because it merges both sounds together. Not ideal for studios.

CLOSED BACK = Most useful for a studio recording. They cut the sound in, but aren’t the most natural sounding.

Question 2

The nature of microphones?

Answer 2

A sensor (input) transducer
Converts acoustic sound into electrical energy
Colours and shapes the sound captured
Vary in responsiveness

Question 3

The main 3 categories of mics.

Answer 3

DYNAMIC = Uses the process called magnetic induction.

CONDENSER = First choice for most vocals and acoustic instrumentals.

RIBBON = For sound sources that are too bright/harsh sounding.

Question 4

Dynamic mic diaphragm

Answer 4

This mic has 3 main parts inside its capsule: A thin metal diaphragm, a metal coil, and a magnet.
Sound waves cause the diaphragm to vibrate. This vibration, in turn, moves the coil.
As a result, the movement of the coil in relation to the magnet translates sound waves into electrical signals.

Question 5

Condenser mic diaphragm

Answer 5

These have a capsule in their guts containing a thin strip of metal called a diaphragm. It’s attached to a metal backplate.
When sound enters the capsule, the diaphragm moves away from the plate. That distance is measured and converted into an electrical signal.

Question 6

Ribbon mic diaphragm

Answer 6

Instead of a dynamic mic’s diaphragm, ribbon mics feature an extremely thin strip of metal suspended in a strong magnetic field.
The ribbon acts as both the diaphragm and the transducer element itself, providing the same kind of sensitivity and transient response you’d expect from a condenser.

Question 7

Pros and cons of dynamic mics

Answer 7

Physically durable.
Withstands high sound pressure levels without distorting.
Moderately wide frequency response.
Generally inexpensive compared to other mics of similar quality.
Punchy, warm sound.

Question 8

Pros and cons of condenser mics

Answer 8

Typically less durable than dynamics.
Handle moderate sound pressure levels and may require a “pad” to deliver high volume signals.
Great high frequency response.
Usually require external power (phantom power).
Use onboard tube or solid state electronics.
Generally have hi-fi sound quality with great clarity.

Question 9

Pros and cons of ribbon mics

Answer 9

Generally more fragile than other mics.
Don’t handle high sound pressure levels well.
Don’t handle bursts of air- e.g. Voice, kick drum.
Limited frequency response.
Generally inexpensive.
Sensitive to preamp colouration.
Renowned for warm, natural sound quality.

Question 10

What is a microphone polar pattern?

Answer 10

A polar pattern = the space around a mic where it picks up sound or is the most sensitive to sound.
Different mics have different polar patterns, and these patterns play a role in determining their best uses.

Question 11

Microphone mounts

Answer 11

If it’s a condenser mic, it’ll need some form of mount.
Works as a mass-spring damping system.
The larger the mic diaphragm, the more they are necessary.
The more directional the polar pattern, the more susceptible the mic will be to LF noise (low frequency).
Reduces LF noise
Also known as ‘spiders’ or shock mounts.
Condenser mics are very susceptible to LF noise
Stage (‘live’) mics are less susceptible to noise
Studio mics often have a wider (lower) frequency range
Shock mounts will decouple the mic mechanically using elastic suspension.
Can be easily broken if mishandled.

Question 12

Microphone wind protection

Answer 12

Known as “pop filter” or “pop shield”, “pop screen”, or “windscreen”.
Removes ‘plosives’ from the recording by dispersing the air flow
Often caused by aspirated plosives (‘f’, ‘t’, ‘k’, ‘d’, ‘b’, and ‘g’).
Air movement can affect the HF by air moving past the grille.
Air movement affects the LF by air pushing on the diaphragm.

Question 13

What are decibels?

Answer 13

A decibel is a measure of sound intensity and amplitude using the decibel (dB) scale.

Decibels use a logarithmic scale
Normal conversation is around 60dB
The ‘threshold of pain’ is around 130 dB

Question 14

Safe sound levels

Answer 14

Decibel levels:

60 dB = ‘conversation’ (safe)
94 dB = ‘Electric drill’ (can listen for 1 hour safely)
120 dB = ‘Dance club’ (danger).

Question 15

DI Boxes

Answer 15

DI Boxes= Direct injection/input boxes
(In the microphones themselves, we have another way of reaching line level: travel through DI Box) .

Resolves an impendence mismatch between electrodynamic guitar pickups and mic preamplifiers. Takes an unbalanced, high-impendence signal and converts it to a balanced, low- impendence signal.

Question 16

Mic and line level

Answer 16

A mic level is a very tiny electrical signal, and it needs to be boosted via the pre-amp to be a line level.
The mic level = tiny
Line level = a bit bigger
Use the mic pre amp to get it there.

Question 17

Stereo mic techniques

Answer 17

When using 2 mics together, it’s called ‘stereo mic techniques’.
Requires a pair of the same mic. Ideally a ‘matched’ pair. Positioning is critical. Creates a stereo image. Be aware of phases issues when using multiple mics.

Question 18

Phase cancellation

Answer 18

We have to be careful of a very important thing – 2 mics recording the same source will not be recording the same sound. This is phase cancellation. When recording using 2 mics, one may receive the sound a fraction earlier. If you combine these 2 signals together, if they’re out of phase, they can cancel each other out.

So beware if using multiple sounds, they will combine, but will sometimes create a chorusing effect called phasing. Generally, phasing with mics = not the most desirable.