digital electronics for audio
Post on 16-Jul-2015
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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.
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
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