MusTech Quiz

Analog recording used various materials for storing information, such as

wax, vinyl, and magnetic tape.

Digital systems record analog signals by sampling them. An audio interface is capable of taking many snapshots of an

analog signal every second in

order to capture and reproduce

the sound.

The sample rate is the number of samples, or snapshots, the converter takes every second.

The

higher the number, the higher the fidelity. Common Sample rates include: 44.1kHz (CD Quality)

• 48kHz (DVD Quality)

• 96kHz (Blu Ray Quality)

• 192kHz

Nyquist Theorem

A periodic signal must be sampled at

more than twice the highest

frequency component of the signal.

8khz

4khz

44.1khz

22khz

48khz

24khz

96khz

48khz

192khz

95khz

Computers store digital information as

1s & 0s

Bit depth determines how much information can

be stored into each sample or snapshot.

Differences in bit depth result in

dynamic range.

16 bit =

65,536 amplitude levels

24 bit =

16,777,216 amp levels

32 bit float =

1.36234x10^8

16 Bit = 96.3 dB – Prolonged sounds

above 90dB can lead to hearing damage.

24 Bit = 144.5 dB – Threshold of pain is

roughly 130 dB

32 Bit Float = 1,528 dB …. This is beyond

the scale of what counts as a sound on

earth.

An audio interface is a soundcard that samples

microphone, line, and instrument level analog signals, and converts them into digital bits.

Mic Level – Typically an XLR input. -60dB ~

30dB. Require a preamplifier to boost to a listenable level. Most interfaces have built in mic preamps.

Line Level – Typically a ¼” balanced input. -10dB to +4dB.

Typically a ¼” balanced input. -10dB to +4dB.

Instrument Level

High impedance unbalanced ¼” input. -30dB

ADAT –

Digital format that can transfer up to 8 audio tracks over an optical cable.

AES/EBU

Digital format that can transfer up to 2 audio tracks over an XLR cable.

s/pdif

Digital format that can transfer up to 2 audio tracks over an unbalanced RCA cable.

Networked Audio – Audio formats such as

Dante and MADI travel through network cables and unmanaged switches. Up to 64 channels over 1 CAT5e cable.

Digital signals will be unstable without the use of a word clock

which will connect units via a BNC cable.

Line Outputs –

10dB or +4dB. These will feed your main monitors, but extra can be used for different monitor mixes, or for

mixing with outboard gear. These can be ¼” or XLR.

Headphone Outputs

Always unbalanced stereo 1/4” outputs. Headphone outs are high impedance speaker level, which

can reach upwards to 136dB.

Digital Outputs

ADAT, AES/EBU, s/pdif, Dante, MADI… All of these formats can be used to send audio to other interfaces or

recording units

Monitor Switching

The ability to use more than one pair of reference monitors.

DSP Monitoring

Some interfaces have their own app that allows you to monitor

in real time without any latency. Some software is basic, while others have their

own plugin suites to add effects like EQ, compression, and reverb. The alternative

to this is software monitoring, which is monitoring through the DAW itself. This

option usually has a more noticeable latency, especially when tracking with plugins

Cascading

Some Thunderbolt interfaces can be daisy chained together, so as

your needs grow, you can add new units for more functionality.

Most interfaces on the market will connect

to your computer

via USB or Thunderbolt.

Thunderbolt has more bandwidth. This means

it can carry more data at a time than USB.