equalisers
DESCRIPTION
Frequency Harmonics Types of EQ; Shelving, Filters, Parametric, Graphic, Q Factor Typical Mixing Desk EQ Typical Software EQ ApplicationTRANSCRIPT
EqualizersAn Introduction to EQ, Types & Application
www.stuartjones.org
EQ
1. Introduction
2. Frequency
3. Harmonics
4. Types of EQ:a. Shelving EQ
b. Filters
c. Parametric EQ
d. Graphic EQ
5. Q Factor
Typical Mixing Desk EQ
6. Typical Software EQ
7. Application
8. Supporting Documents
Agenda
EQ
Introduction
EQ
What is EQ?
Control of the amplitude of areas of frequencies.
Why is it called E.Q.?
Early telephone systems used EQ to balance or equalise input with output to
compensate for deterioration within long cables.
EQ
Nowadays EQ gets used for more creative purposes such as filter sweeps.
EQ
Frequency
EQ
Frequency
Time
Am
plit
ude
0
+
-
t
The rate at which the source oscillates is the frequency of the sound wave it produces, and is quoted in hertz (Hz) or cycles per second (cps). 1000 hertz is
termed 1 kilohertz (1kHz)
EQ
The lowest string of a guitar vibrates approximately 82
times per seconds.
This means that a low ‘E’ (E2) on a acoustic guitar has
a frequency of 82 Hertz.
A standard bass is an octave below at 41.2Hz (E1)
Frequency
EQ
The lowest note on a standard piano is 27.5 Hz, and the highest note is
4186 Hz.
However, as all sound contain many frequency components. These are
known as Harmonics.
In the case of the piano, frequencies will extend above 4kHz.
Frequency
EQ
3. Harmonics
EQ
Harmonics
In this example, the sound is toggled between a sine wave and a square wave each at 100Hz.
The Sine wave is a simple waveform containing no harmonic content.
However, the square wave is rich in harmonics and extends far beyond the fundamental frequency.
EQ
Image showing a Square Wave with a fundamental frequency at 100Hz.
The chart on the right shows its harmonic content
Harmonic Frequency Amplitude
f 100 1
1st 300 1/3
2nd 500 1/5
3rd 700 1/7
4th 900 1/9
Harmonics
EQ
This example shows middle C on a piano. This has a fundamental frequency of 261.626 Hz and also contain components at 523Hz, 1046Hz, 2093Hz and so on.
Harmonics
Types of EQ
EQ
A - Shelving EQ
EQ
Shelving EQ
High Shelving Band
(10 decibel (dB) boost applied at 1kHz)
EQ
Shelving EQ
Low Shelving Band
(10 decibel (dB) boost applied at 1kHz)
EQ
B - Filters
EQ
Lowpass Filter (Showing 1kHz Cut @ 24dB/octave)
Filters
EQ
Highpass Filter (Showing 1kHz Cut @ 24dB/octave)
High pass filters are usually found on mixing desks. Used to cut out unwanted rumble.
Filters
EQ
In this example, for every octave beyond the 10kHz cut off point, the signal is attenuated by
6dB
EQ
Now the filter is set at 48dB/Oct the slope is much steeper
EQ
C - Parametric EQ
EQ
This has three controls:
1.cut/boost - dB
2.sweep control - Hz
3.‘Q’ factor - The ‘Q’ factor control adjusts the width of the band of frequencies to be attenuated. (how steeply it slopes).
Parametric EQ
EQ
Q Factor
EQ
Q Factor
3dB
f0f1 f2frequency (Hz)
Level (d
B)
Low Q
EQ
3dB
f0f1 f2frequency (Hz)
Level (d
B)
High Q
Q Factor
EQ
Peaking band - wide bandwidth (low Q)
Q Factor
EQ
Peaking band - narrow bandwidth (high Q)
Q Factor
EQ
D - Graphic
EQ
A series of fixed bands that can boost or cut. However, frequency bands cannot be moved. The more bands the better.
Professional graphics have 31/32 bands and are stereo. Some uses for graphic EQ:
• Mastering – When mastering a final mix.
• Live – Different venues have different acoustics. You could use a graphic Eq for the front of house sound or the on stage
monitor mix if your lucky enough to have two EQs.
• More flexible.
Graphic
Typical Mixing Desk EQ
Audient ASP8024 EQ
1
2
3
4
HF Shelving EQ - 2 band boost/cut for high and low
frequencies. Switchable between 10kHz and 18kHz.
LF Shelving EQ - 2 band boost/cut for high and low
frequencies. Switchable between 50Hz and 100Hz.
Places the eq in circuit
5
6
Parametric EQ - Boost/Cut (dB)
1
35
4
2
6
6
Parametric EQ - Sweep (kHz)
Parametric EQ - Q Factor
7 Places the eq in the short fader path (before tape)
EQ
Typical Software EQ
EQ
Logic Pro Channel EQ
1 12 23 3 3 3 1
2
3
Shelving EQ
Filter EQ
Parametric EQ
4
4 Q Factor
EQ
Application
EQ Source - http://www.offbeat.co.uk/wp-content/uploads/2012/06/eq-chart.pdf
These types of EQ charts are
common place and act as a good
introduction to instrument frequencies.
EQ
1. Switch out the equaliser.
2. Listen to the raw sound.
3. Imagine the perfect sound.
4. Dual in an EQ setting that you hope will match your imagination.
5. Put the EQ in.
6. Not the right sound? See 1
EQ Tips
EQ
The human ear is great at comparing between toggled states (A:B). It is not so good at following slow changes because
it quickly adapts and loses perspective.
Why?
EQ
Web
• http://www.stuartjones.org.uk/Student_Resources/Studio_Tutorials/Entries/2010/7/4_AUDIENT_ASP8024_-
_Equaliser.html
• http://www.wikirecording.org/EQ
• http://www.independentrecording.net/irn/resources/freqchart/main_display.htm
• http://www.offbeat.co.uk/wp-content/uploads/2012/06/eq-chart.pdf
• http://www.rs-met.com/documents/tutorials/FrequencyAndPitch.pdf
• The Mix Engineers Handbook - Bobby Owsinski
Supporting Material
• http://quiztones.net/ - Free ear training app
Books
• Creative_Sequencing_Techniques_for_Music_Production_(by Andrea Pejrolo)
References
EqualizersAn Introduction to EQ, Types & Application
www.stuartjones.org