This document discusses different types of equalizers used in audio production including graphic, shelving, and parametric equalizers. Graphic equalizers have a fixed number of frequency bands that can each be boosted or cut using individual gain controls. Shelving equalizers broadly boost or cut the high and low frequencies, while parametric equalizers allow control over the central frequency, gain, and bandwidth (Q-factor) of an adjustable frequency band, providing the most precise equalization capabilities.

1. Equalizers
Types of EQ

2. The concept of gain
It is usually measured in dB
Positive dB = increment in signal’s
energy
Zero dB = No change (unity gain)
Negative dB = decrement in
signal’s energy
Infinite dB = Complete attenuation

3. Interesting facts of dB’s
0 dB means “no change” in the signal
1 dB change is barely heard by some people
3 dB is the minimum perceived change of loudness for most people
10 dB change sounds twice as loud

4. Graphic EQ
It has a fixed number of bands (frequency ranges)
Each band has ist own gain control and fixed bandwidth
10 bands are ok for music adjustments
31 bands are standard for PA systems adjustment

5. Graphic EQ response
9-band GEQ
Each band has its own gain
control (+/- dB)
The bandwidth of each band is
fixed
It is good for general equalization,
but it is limited for professional
audio production

6. Shelving EQ
Also known as Bass and Treble
controls
They change the hi and low end of
the range
The control a very wide bandwidth
It can’t control specific frequencies

7. Parametric EQ
It is the most complete equalizer
It can control three parameters:
Central frequency
Gain (boost or cut)
Q (bandwidth)

8. Q (quality factor)
It is a parameter related to the
bandwidth
Low values = wide bandwidth
High values = narrow bandwidth
Low Q value
High Q value