Hazel Meades
Mind Map by , created over 5 years ago

A Levels Music Tech (A2) Mind Map on EQ, created by Hazel Meades on 03/12/2014.

Hazel Meades
Created by Hazel Meades over 5 years ago
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1 What is it?
1.1 Initially used to correct imperfections in the sound.
1.1.1 As technology improved it started to be used for different purposes. EQ units offer a combination of different filters that can be used together. Plug-in EQs can offer an almost limitless supply, hardware EQs are limited by their design.
1.2 It was initially used to compensate for the loss of upper frequencies on long cable runs.
1.2.1 BBC - King's College
1.3 Mid freq. boost = boxy sound
1.4 Top freq. boost = tinny sound
1.5 EQ can be used in combination with panning to separate instruments
1.6 General rules:
1.6.1 Trust ears over eyes
1.6.2 1. Set frequency area 2. Adjust frequency range 3. Boost/cut
1.7 Used to highlight instrumental tones, remove unwanted noise such as feedback, rumble etc.
2 Parametric EQ
2.1 Based on a band-pass filter
2.2 Has access to the same Q, boost/cut and centre frequency.
2.3 Adjustable filter sections are provided so the user can effect a variety of bandwidths.
2.4 Gives the user the ability to finetune their recording.
2.5 Choose a centre frequency and move it up, down and around.
2.5.1 Sweeping - moving the frequency (with the gain set high) to search for where EQ should be applied
2.6 More specific and specialist in comparison to graphic
2.6.1 Requires more expertise
2.7 More precise adjustments
2.8 Semi-parametric EQ AKA sweepable filter: allows user to control amp and freq but uses a pre-set bandwidth for the centre frequency.
3 Graphic EQ
3.1 A group of band-pass filters.
3.2 Centre frequency is equally spaced.
3.2.1 Octaves apart
3.3 Spacing is agreed through musical intervals.
3.4 Simpler to use compared to parametric EQ but less precise.
3.5 Often used to compensate for a venue's acoustics.
3.6 Rows of adjustable sliders so you can home in on specific frequencies
3.7 Input signal is sent to a bank of filters, which pass the portion of the signal present in its own freq. range or band.
3.7.1 Filter is adjusted via slide control to boost or cut freq
4 When to EQ?
4.1 Can do it continously
4.2 Can do it at the end after you've got all the audio
4.3 Depends on the creative/practical purpose
4.4 General rule is to EQ later on
4.5 Makes the piece sound nice as a whole
5 Shelf EQ
5.1 Cuts or increases all frequencies above or below the cut off evenly
5.1.1 Used in common tone controls
6 Fixed EQ
6.1 Bass, treble, mid
7 History
7.1 Langevin Model EQ-251A - 1st EQ to use slide controls
7.2 Type 7080 developed by Art Davis' Cinema Engineering - 1st true graphic EQ
7.3 Daniel Flickinger introduced 1st parametric EQ in 1971
7.3.1 He achieved filtering circuits that were impossible before. 6 knobs controlled sweepable features.
7.3.2 Most modern day parametric EQ designs rely on the designs of Flickinger, Massenberg and McNeal
7.4 In 1990s and 2000s parametric EQs became increasingly available as Digital Signal Processing equipment in the form of plug-ins for DAWs.
7.4.1 Standalone outboard gear versions were introduced after software versions and referred to as Digital Parametric Equalizers