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SOUND 2
Michael Drolet -- 2016
Home Reaper -- ReaEQ VST Plugin



One of the plugins that comes with REAPER is ReaEQ.  It's a software equaliser or EQ.  Remember the EQ on the Mackie console?
 
The EQ on the console is a set of hardware controls that can manipulate or change the frequency content of sound passing through it.

The Mackie EQ has four bands of equalisation -- it can manipulate sound content over four different ranges or bands of frequency.
Mackie EQ
Another, more general term for a band of  EQ is filter.
A filter is usually described by the frequency at which it boosts or cuts the level of sound content by 3dB.  This is called the cutoff frequency.


The ReaEQ can synthesize an equaliser with an unlimited number of bands.   Each band can be one of a number of types of filter.
    • Low pass
    • High Pass
    • Low Shelf
    • High Shelf
    • Band
    • Notch
(and a few more less common ones.)


Let's look at a few of the possibilities, one by one.


A "HIGH PASS" filter allows all sound above its cut-off frequency to pass through.  It may be sometimes referred to as a "LOW CUT" filter, because all  sound below its cut-off frequency is blocked.

The filter shown on the right is set the same as the LOW CUT filter on the Mackie console. (The one used to remove air conditioning rumble.)

The cut-off Frequency is set to 80Hz.  The response at 80Hz is 3dB lower at 80 Hz compared to higher frequencies. One octave lower (40Hz) it's down by a further 6dB (-9dB).
High Pass

A "LOW PASS" filter allows all content below its cut-off frequency to pass through.  It may be sometimes referred to as a "HIGH CUT" filter, because all content above its cut-off frequency is blocked. Low Pass

A "LOW SHELF" filter is like the BASS tone control on your car radio or home stereo.  (-- yes, "it's all about that BASS -- no TREBLE".)

The BASS control can be used to cut or boost low frequency content.

This one is set to cut all content below 200Hz by (about) 6dB.  At 200Hz, its response is cut 3dB, everything one octave lower (below 100Hz) is cut by 6 dB. 

Graphically, this resembles a shelf, hence the name.
200Hz Low
                Shelf (Cut)

This one is set to boost all content below 200Hz by (about) 6dB. 

At 200Hz, content is boosted 3dB, everything one octave lower  (below 100Hz) is boosted by 6 dB.
200Hz Low
                Shelf (Boost)

A "HIGH SHELF" filter is like the TREBLE tone control on your car radio or home stereo.  It can be used to cut or boost high frequency content.

This one is set to cut all content above  6000Hz by 6dB.

At 6000Hz, its response is cut 3dB, everything one octave higher (above 12000Hz) is cut by 6 dB.

6000Hz High
                Shelf (Cut)


This one is set to boost all content above  6000Hz by 6dB. 

At 6000Hz, its response is boosted 3dB, everything one octave higher (above 12000Hz) is boosted by 6 dB.
6000Hz High Shelf (Boost)

A "PARAMETRIC" or "BAND" filter can be used to boost or cut all content over a certain range or band of frequencies.

This one is set to reduce content centered on 1000 Hz by 6dB. 

Its Bandwidth is set to 2  octaves.

That means its cutoff frequencies (3dB points) are one octave below (500Hz) and one octave above (2000Hz) the centre frequency -- a total of two octaves. 
1000Hz Band Cut


This one is set to boost content centered on 1000 Hz by 6dB. 

Its Bandwidth is set to 2  octaves.

That means its cutoff frequencies (3dB points) are one octave below (500Hz) and one octave above (2000Hz)
the centre frequency -- a total of two octaves. 
1000Hz Band
                Boost

A "NOTCH" filter can be used to remove a very specific tone or frequency. It's a very narrow BAND CUT filter.

This one is set to notch out HUM, 60Hz noise caused by electrical circuitry. 

It's bandwidth is set to 0.1 octaves, so as to affect only the hum, not higher or lower frequencies.
60Hz Notch

While I've only shown one band at a time for clarity, ReaEQ can employ many bands of equalisation (many filters).

The default is four bands as shown here.

Although four bands are shown, they're all set to zero-state or flat -- 0dB boost or cut.

This EQ wouldn't affect the content at all, until the "Gain" slider is of one of the bands is moved.
 
ReaEQ Default
              Flat

We could make adjustments to the individual bands to yield something like this.

The adjustements shown here are arbitrary, just for illustration. 

Normally we would adjust the equaliser by listening to the result.

ReaEQ Default
              Arbitrary

What would we use ReaEQ for?

Why would we want to equalise a sound?
 
Take a look at this graphic.

Click on image to download *.pdf version

Subjective Musical Qualities

On the console, we can use an equaliser to adjust the subjective qualities of the sound, just like we can use gels to filter a white light source to create a different mood.

In Reaper, we can use ReaEQ
  • to have more "thump" on the kick drum (BAND EQ, +3dB @ 70Hz)
  • to have less "sizzle" on the hi-hat (BAND EQ,, -3db @ 11kHz)

Click here to download *.pdf table of ReaEQ settings.