An analog signal is captured as an exact replication of the sound

Like a film camera

A digital signal converts the information of an analog signal into a series of binary code

Binary code is made up of 1s and 0s

Each 1 or 0 is called a bit

Whenever you record with a computer, you are converting sound, mechanical energy, into digital electronics

All digital electronics are represented by binary code, which is a sequence of 1s and 0s

The number of times per second and the amount of each sample taken is very important for good quality recording

Sample Rate

oThe number of times per second that the system

measures the volume level of the sound

oCD audio is 44.1 kHz (44,100 samples per second)

oReproduction is about half of the rate: 22.05 kHz for CD

oHumans perceive max 20 kHz (16 kHz for most people)

oHigher rates still important (events between samples)

Analog Signal Sampled Signal

This work is licensed under a Creative Commons Attribution-Noncommercial-Share Alike 3.0 United States License.

Bit depth

oHow many bits of information is

taken with each sampleo16 bit audio gives a DR of 96 dB ( 16 x 6 = 96 )

o24 bit audio gives a DR of 144 dB ( 24 x 6 = 144 )

oBecause of noise floor, usuable DR is less

16 bit = 90 dB

24 bit = 138 dB

oDR of human hearing is roughly 140 dB

oDR of music in a concert hall does not exceed 80 dB

oDR of human speech is normally about 40 dB This work is licensed under a Creative Commons Attribution-Noncommercial-Share Alike 3.0 United States License.

Set your bit depth to 16 Bits

The buffer size is the amount of data that is currently being processed

The larger the buffer size, the longer it takes to read the incoming data

Therefore, when recording, you will hear a delay

The delay depends on the audio interface

Latency is the delay between when you play and when you hear it in your headphones on the computer. Also happens with MIDI.

The larger the buffer size, the longer the delay in the audio processing, or sound heard

The smaller the buffer size, the shorter the delay The larger the buffer size, the higher the quality The smaller the buffer size, the lower the quality Therefore, when recording, you should raise the buffer

size and listen through the monitor mix on the audio interface.

When recording MIDI, you should lower the buffer size so that you have no delay between when you hit the key and when you hear it.

Engineer Harry Nyquist came up with this concept

As you lower the sample rate, you cut out the high frequencies

The sampling rate has to be twice the highest frequency to be heard on a digital recording

2x = Sample Rate where x = highest frequency

Each 1 or 0 is called a bit

8 bits are in a byte Ex> 10110010 = a byte of information

1024 bytes are in a KILOBYTE (KB)

1024 KB are in a MEGABYTE (MB)

1024 MB are in a GIGABYTE (GB)

1024 GB are in a TERABYTE (TB)

1 Hz = 1 cycle per second

1000 Hz = 1 kHz (1 kilo herz)

1000 kHz = 1 MHz (1 mega herz)

1000 MHz = 1 GHz (1 giga herz)

When purchasing a computer for audio recording, you need to look at:

1. RAM – Random Access Memory - how much can it do at one time?

2. Speed - how fast does it process?

3. Space – how much information can it hold?

Random Access Memory This is how many activities the

computer can do at one time

You want at least 8 GB (8 gigabytes) of RAM

Preferably 16 GB This will determine how long it takes to

start up computer Also determines how long it takes to

open a program Also determines whether you can use

multiple programs at once

CPU = Central Processing Unit

This is the processor for the whole computer

You want the SPEED to be FAST!! This determines latency in your recordings/MIDI (as well as audio int.)

Speed is measured in Hz, just like audio frequencies

You want 2.6 GHz or more clock speed!

The more processors, the faster the processing

Example: 2 GHz Intel chip with 8 core will be faster than a 3 GHz chip with 2 core processors

https://www.cpubenchmark.net/high_end_cpus.html

A typical multi track recording is 10 – 100 gigs.

You want at least 500 GB Hard Drive Space – this is how much room you have for all your files

ProTools requires 2 hard drives

Store large files in the cloud

MAC = OS X Yosemite (2015)

64 Bit PC = Windows 8 (2014

and later)

Windows 8 uses 64 Bit processing

4 Minute MP3 file = 5-6 MB (at 192 kbps)

4 minute WAV file = 40 MB

4 minute OGG file = 4 MB

4 minute FLAC file = 20 MB