EQ

EQ

1. What is it?

   • Initially used to correct imperfections in the sound.
     • 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.
   • It was initially used to compensate for the loss of upper frequencies on long cable runs.
     • BBC - King's College
   • Mid freq. boost = boxy sound
   • Top freq. boost = tinny sound
   • EQ can be used in combination with panning to separate instruments
   • General rules:
     • Trust ears over eyes
     • 1. Set frequency area
       • 2. Adjust frequency range
         • 3. Boost/cut
   • Used to highlight instrumental tones, remove unwanted noise such as feedback, rumble etc.

2. Parametric EQ

   • Based on a band-pass filter
   • Has access to the same Q, boost/cut and centre frequency.
   • Adjustable filter sections are provided so the user can effect a variety of bandwidths.
   • Gives the user the ability to finetune their recording.
   • Choose a centre frequency and move it up, down and around.
     • Sweeping - moving the frequency (with the gain set high) to search for where EQ should be applied
   • More specific and specialist in comparison to graphic
     • Requires more expertise
   • More precise adjustments
   • 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

   • A group of band-pass filters.
   • Centre frequency is equally spaced.
     • Octaves apart
   • Spacing is agreed through musical intervals.
   • Simpler to use compared to parametric EQ but less precise.
   • Often used to compensate for a venue's acoustics.
   • Rows of adjustable sliders so you can home in on specific frequencies
   • Input signal is sent to a bank of filters, which pass the portion of the signal present in its own freq. range or band.
     • Filter is adjusted via slide control to boost or cut freq

4. When to EQ?

   • Can do it continously
   • Can do it at the end after you've got all the audio
   • Depends on the creative/practical purpose
   • General rule is to EQ later on
   • Makes the piece sound nice as a whole

5. Shelf EQ

   • Cuts or increases all frequencies above or below the cut off evenly
     • Used in common tone controls

6. Fixed EQ

   • Bass, treble, mid

7. History

   • Langevin Model EQ-251A - 1st EQ to use slide controls
   • Type 7080 developed by Art Davis' Cinema Engineering - 1st true graphic EQ
   • Daniel Flickinger introduced 1st parametric EQ in 1971
     • He achieved filtering circuits that were impossible before. 6 knobs controlled sweepable features.
     • Most modern day parametric EQ designs rely on the designs of Flickinger, Massenberg and McNeal
   • In 1990s and 2000s parametric EQs became increasingly available as Digital Signal Processing equipment in the form of plug-ins for DAWs.
     • Standalone outboard gear versions were introduced after software versions and referred to as Digital Parametric Equalizers

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