Conquering_EQ. 7.96MB 2013-07-11 22:03:25
Conquering
EQ
By Eddie Ba zil, Sa m ple cr a ze .com
This book and it s cont ent s are © 2005 Sam plecraze.com . All right s
reserved. Unaut horised copying, re- selling or re- product ion of t his
book or any aspect of t his book is st rict ly forbidden.
Con t e n t s
i. How t o use t his book
1 . I nt roduct ion t o Equalisat ion
2 . Sound
3 . Com ponent s of Sound
4 . Midi and Frequency Chart
5 . Fundam ent als and Harm onics
6 . To Cut or t o Boost
7 . Term inology and definit ions- Filt ers
8 . Type of EQ
9 . Phase t he bi- product
1 0 . Let it begin – Drum s – Kick
1 1 . Snare
1 2 . Drum Loops
1 3 . Voice
1 4 . Prim ary and Secondary EQ
1 5 . Voice Exam ples – Double Tracking
1 6 . Voice EQ Addit ional Exam ples
1 7 . Mixing EQ – Gospel
1 8 . Mixing EQ – Exam ples
1 9 . Final Word
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i. H ow To Use Th is Book
Pr e fa ce – H ow t o Use This Book
Tut orial Files
Many of t he t ut orials in t his book have associat ed files t hat are used t o explain t he concept s
m ore clearly t o you. All t ut orial files are included in t he ‘sounds’ folder t hat cam e wit h t his book and
Make sure you ext ract all t he files correct ly wit hin a program such as Winzip ( w w w .w in zip.com ) .
Searching
The beaut y of a PDF is t hat you can search it s cont ent s very easily from wit hin t he free Abode
Acrobat reader. I recom m end you inst all t he full version ( it ’s st ill free) which is available from
Here
ht t p:/ / w w w .a dobe .com / pr odu ct s/ a cr oba t / r e a dst e p2 .ht m l
To search t his Ebook, sim ply go t o ‘Edit ’ and select ‘Search’. Alt ernat ively, if you have a PC j ust
press ‘CTRL & F’.
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1 . I n t r odu ct ion t o Equ a lisa t ion
Alm ost every forum I visit , or every 1 in 5 em ails I receive, t he subj ect m at t er t hat is m ost
discussed is EQ ( equalisat ion) .
What it is, how t o use it and when t o use, which one t o use and which is t he best for t he given
t ask and, m ost im port ant ly, what frequencies cover cert ain sounds. Everyone is aft er a quick
form ula.
What m ost people do not realise is t hat EQ is one of t he m ost powerful t ools available t o a
producer, and m ast ering house, and t o m ast er t his t ool one needs t o underst and frequencies.
When t he t erm 'EQ' ( equalisat ion) is m ent ioned, people invariably t hink of t he t one cont rols on
t heir hi- fi syst em s. Knowing t his act ually gives you a head st art . The fact t hat a sound can be
m ade warm er or punchier already gives you an idea as t o what EQ is. You know t hat by
t urning t he t reble knob up on your hi- fi m akes t he sound bright er, t urning it down m akes t he
sound less bright and m ore fluffy or woollen.
What you are act ually doing is boost ing, when you t urn t he knob ‘up’, and cut t ing, when you
t urn t he knob ‘down’, t he predet erm ined frequencies t hat are assigned t o t hat knob.
Before we get deep int o EQ, let us look back a t ad at why EQ was int roduced int o our lives in
t he first place.
H ow a n d W h y
This whole headache began in t he broadcast ing field. Blam e t hose guys.
Act ually t he first ever inst ances of equalisat ion was in t he com m unicat ions indust ry. EQ was
used t o count eract som e of t he problem s in t elephone syst em s.
Tone cont rols were creat ed and used t o com pensat e t echnical inaccuracies in t he recording
chain, m ore not ably, com pensat ing for m icrophone colourat ion and room acoust ics. EQ was
used as a m eans of cont rolling t he gain of a range of frequencies.
I n t hose days, a st andard, bass, m iddle and t reble gain cont rol were all we had. Today, we are
act ually spoilt for choice as t here are so m any param et ers t hat we can cont rol on any t ype of
EQ, t hat it has act ually becom e confusing.
From correct ive EQ, we have com e a long way, t o creat ive EQ.
I do not want t o bore you wit h t he hist ory of EQ or who invent ed what . You can t rawl t he net
for som e excellent art icles on t his subj ect . What I want t o do is t o dive in and get you st art ed
on t his det ailed and confusing subj ect .
However, before I get int o t his deeper, I need you t o underst and ‘sound’ and ‘frequencies’.
Those t hat have read m y t ut orials on m y websit e ht t p: / / www.sam plecraze.com will know t hat
I have covered t he subj ect of sound in det ail. For t hose who cannot be bot hered t o read t hose
t ut orials, here is t he condensed version:
To underst and any part of EQ you need t o underst and sound, what it is, how it m oves, how we
perceive it and why we perceive it t he way we do.
Once you underst and t his t hen shaping it or m anipulat ing it becom es so m uch easier.
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Ta ggin g
The m et hod I am going t o use t o help you in underst anding t he t erm inology and definit ions
and what each part is and does is a syst em t hat has exist ed for cent uries and works ext rem ely
well in every aspect of your life.
I t is a syst em t hat speed reading specialist s, m em ory recall cent res and even high powered
execut ive t raining program s use. I t is called ‘Ta ggin g’ or ‘Lin k in g’. I t is t he sim plest and
m ost effect ive ‘rem em bering’ t ool.
You have used it since you were a child. Every t im e you were asked t o draw a house in a field,
you would draw a st rong big house on green grass wit h a huge sun t hat was always yellow,
red or orange wit h a t ree and a cow. Of course som e people drew t he sam e t opic in t he
Picasso m ould or surreal a la Dali, but on t he whole, t he pict ure is alm ost always t he sam e.
Why? Because we rem em ber t hings t hat have an effect on our senses, be it t ouch, sm ell,
t ast e, hearing or visual. The st rong colour of t he sun and t he size of it are a great way of
rem em bering what a sun looks like. The big house in t he cent re of t he drawing will always
st ay in your m ind. The cow is always alone and st rongly accent uat ed and is always t ot ally out
of size in com parison t o t he house. The ground is always green grass and t he sky always blue
and if t here is a cloud t hen it is always one big round cloud.
These im ages are st rong and always st ay in m em ory. The sam e t echnique is used in t agging.
We creat e an im age rich in as m any of t he senses as possible and t hat will always st ay in our
m inds, far st ronger t han having t o learn t hings in parrot fashion.
I have used t his t echnique all m y life and now do it unconsciously. Not only does it work but it
is also fun as t he t ool for t agging is your im aginat ion and not hing is st ronger or st ays longer in
your m em ory t han an im age creat ed out of your im aginat ion.
Probably by now you feel t hat I require a great deal of help and t hat t here are cert ain places
for people like m e, com fort able places t hat offer 24 hour securit y and in dept h t reat m ent . You
are probably right but not for t he reasons for t his t ut orial.
So, let us begin t his j ourney.
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2 . Sound
Sound is t he displacem ent of air around t he source and how we perceive t hat displacem ent .
Right , what does t hat m ean?
Think of t he best and m ost com m only used analogy: t hat of dropping a st one in a pond and
wat ching t he ripples form . The ripples always m ove away from where t he st one m eet s t he
wat er ( source) . The air displacem ent is t he ripples creat ed by t he dropping st one. I n t his case
we see t he ripples. I n t he case of sound we hear t he ripples ( t he displaced air) .
How do we hear t he displaced air?
Our eardrum s pick up t he displaced air and our brains t hen process t he dat a as sound. I could
go int o t he det ails about t he ear m uscle vibrat ing and t he eardr um being a cham ber and on
and on and on…but t hat is not what you want t o know.
The t agging im age here is t he r ipple .
Has it ever occurred t o you t hat when a pict ure is drawn of a guit ar am plifier, wit h a guit arist
playing loudly, you always see a few arced lines drawn com ing out of t he am plifier?
Exact ly like t he ripples in t he pond. I n fact t his im age is always t he sam e for speakers t hat are
playing m usic. The pict ure or t ag here is, again, always t he sam e wit h arced lines st art ing as
sm all arcs growing t o large arcs and away from t he speaker.
Keep t hat im age in your head and t hat const it ut es sound, or m ore precisely, sound waves, like
t he ripples.
Fig 1 illust rat es t his. I have deliberat ely used freehand so it will m ake you laugh and st ay in
your m em ory.
Fig 1
SOUN D W AVES
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3 . Com pon e n t s of Sou n d
Now let s us look at t he com ponent s t hat m ake up sound.
There are t h r e e , and are really quit e sim ple t o underst and if you apply t he ripple analogy.
The displacem ent of air or air pressure as is m ore com m only known, creat es t he waves in fig
1 and is know as Sound Waves. The rat e at which t hese waves occur is called Fr e que n cy.
So our first com ponent of sound is Fr e qu e n cy.
i. FREQUEN CY
This is sim ply calculat ed at how m any cycle s ( waves) occur every second. These cycles are
repeat ed so really we only need t o look at how m any cycles ( waves) occur in one second.
The result is m easured as cycles/ second and t his unit of frequency is called a Hert z and t he
abbreviat ion is Hz.
You cannot get sim pler t han t hat …..how m any cycles hit you in one second.
Heinrich Hert z was a dude who worked wit h wavelengt hs and frequency, so we have t o t hank
t he m an and it seem ed only right t o nam e t his lit t le calculat ion aft er him . I always rem em ber
t he rent - a–car agency when I t hink of frequencies and Hert z and it m akes m e sm ile every
t im e so rem em bering t hat nam e is easy.
To give you an exam ple of how easy t his is check out t he following:
I f you had 50 cycles hit you in one sec t hen t hat would be a 50 Hz wave. There, sim ple and
m akes you look cool in t he bar when you want t o im press som eone…or m aybe not .
So it also follows and m akes com plet e sense t hat if you had 10,000 cycles per second t hen
t hat would be 10,000 Hz, but , because we don’t want t o have t o writ e so m any num bers every
t im e a t housand appears we use t he k let t er t o m ean a t housand.
So, 10,000 Hz is now writ t en as 10 kHz. Now you look even cooler. There is a reason we do
t his and it ’s not because we want t o look deep and com plicat ed individuals but sim ply because
of all t he work t hat has been carried out on our hearing range in t he past .
And a range was form ed, sure it varies but generally speaking, our hearing range is anywhere
from 20 Hz, deep, t o 20 kHz, high.
Now, let us t hink of t hat range and m ake life a lot easier by giving nam es you recognise t o t he
frequency range.
So: bass, m idrange and t reble are easy t o rem em ber and if you are old enough t hen t hat ’s
about all t hat used t o exist on hi- fi syst em s back in t he days of arm our and j oust ing. Now let
us give t hose t ags a frequency range and t hen all becom es so m uch easier t o underst and.
Bass: 10 Hz t o 200 Hz
Midrange or m id, a t erm you hear a lot of engineers use: 200 Hz t o about 3 kHz.
Treble: 3 kHz t o what ever t he highest value you can hear.
I t is im port ant t o m ent ion, at t his st age, m y beliefs regarding frequency chart s. I am not
t alking about t he cycles chart com ing up in t his t ut orial, but about chart s depict ing ranges of
inst rum ent frequencies.
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I put very lit t le im port ance on frequency chart s for inst rum ent s. Alm ost every websit e you
visit , t hat displays a frequency chart , you will see t hat t hey all vary in t heir ranges. The reason
for t his is quit e sim ple. Ranges can be bot h inaccurat e and broad. I t hink it is a wast e of t im e
displaying chart s, because alm ost every st udent I have t ut ored, t hat has t ried t o use one of
t hese chart s, has st ill ended up request ing help on EQ.
I t is far m ore helpful t o underst and frequencies and sound, t han it is t rying t o use a chart of
t his t ype.
Once you underst and t he cont ent of t his E- book, you won’t need a chart .
I will, of course, give exam ples of cert ain sound frequency ranges and what happens when
you apply cert ain EQ param et ers t o t hem .
So we now know t hat higher frequency sounds are higher in pit ch as t here are m ore cycles per
second and lower frequency sounds have fewer cycles per second. Easy.
Right now I t hink it is im port ant t o show you a frequency chart for all t he not es on a keyboard
or scale and t he m idi not e num bers as well as t his will com e int o play at a lat er dat e when we
deal wit h synt hesis and program m ing wit h t he use of m idi.
You do not need t o learn t his chart in parrot fashion but it is im port ant t o underst and som e of
t he frequencies t hat are used as, lat er, you will need t o know t hese frequencies so t hat if you
need t o use EQ t o shape a sound or rem ove or add cert ain frequencies, t hen t he chart can
prove t o be invaluable
.
I n m ost cases, you only need t o recognise t he m ain frequencies for cert ain not es. For
exam ple: C4 at 261.63 Hz is a great reference point , because t hen you can find, easily, C5 or
C3 et c….
I cannot st ress how im port ant frequencies are for t he underst anding of sound and EQ.
Engineers live by t hem as do producer s and Sound Font developers.
I f t here is one piece of inform at ion t hat overrides any ot her in t erm s of im port ance it is t he
underst anding of frequencies.
How oft en have you t ried t o m ix your t rack only t o be m yst ified by t he result ?
Term s like ‘m uddy’ or ‘t hin’ spring t o m ind and t hese are all because t he m ixer or producer
does not have an underst anding of frequencies and t heir effect on ot her frequencies in a m ix.
Underst and t his basic concept and you will be arm ed wit h t he m ost pot ent weapon.
Waveform s and frequencies go hand in hand.
Underst and t hese t wo and t he rest is all about using t he t ools.
So, let ’s get on wit h t he CH ART
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4 . M idi a nd Fr e qu e n cy Ch a r t
M idi N o
N ot e
Ke yboa r d
Fr e q
As you can see from t he funky chart t hat for every oct ave you go up you double t he frequency
and it is t he sam e in reverse, for every oct ave t hat you go down, you halve t he frequency.
Exam ple: C4 is 261.63 Hz. To get t o C5 we double t he frequency so it is now 523.25 Hz. And
if we want ed t o go from C4 t o C3, it would be 130.81 Hz. There, a few secret s t o t hrow about .
Now let us creat e t he t ag for t his whole sound t hing.
I always im agine a wave as a 3 dim ensional ent it y and wit h t hat I at t ach colours and size. So,
for a low frequency wave I will t hink of it as a large and flowing wave wit h nice warm colours
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like orange or deep red and t he whole im age is nice and slow. For higher frequencies I use
sm aller and fast er waves and in harder colours like bright yellow or st riking blue. This im age is
t hen enhanced furt her by having a person st anding in front of t he waves, usually m e, but m y
nam e is Hert z and I am list ening t o t hese waves in a rent a car. Alt hough t his m ay now
confirm t he urgency for m e t o seek t herapeut ic help, it is t he best way for m e t o rem em ber
t hings.
You can creat e what ever im ages or st ory lines t o t he definit ions in t his t ut orial. They are your
im ages and m ust work for you.
Next on t he sound m enu is Am plit u de :
ii. AM PLI TUD E
Generally speaking t his m eans t he loudness or level of a sound or w a ve for m .
I prefer t he word w a ve for m for sound as it is t he form or shape t hat t he waves t ake and t he
furt her we go int o t his t ut orial t he m ore t hat t erm will m ake sense as waveform s vary in
shape and charact er so, from now on, I want you t o use t he word w a ve for m for sound.
I t is bet t er defined wit h a sim ple graph. I n fact , now is as good a t im e as any t o int roduce
you t o graphs. Ent er fig 2 .
Fig 2
As you can see, t he waveform , it ’s act ually a sine wave but don’t worry about t hat for now, is
2 cycles and I have arrowed in t he second cycle, no difference which cycle I arrow as t hey are
bot h repeat s. Anyway I had t o arrow t he second cycle so as not t o int rude on t he am plit ude
line in t he first cycle.
The height or peak of t he waveform is t he am plit ude and t he lengt h is m easured as 2 cycles
and t his is done very sim ply.
I m agine a sound and how it st art s. I t st art s from 0 t hen goes up, hangs about and t hen drops
off.
I n t he diagram you can see t he waveform st art s at zero, goes up, drops t o zero t hen goes t o
t he negat ive area and t hen clim bs t o zero again. This is using t he wave t heory we defined
earlier and all w aveform s are represent ed like t his, as a graph, and how each cycle behaves or
how a num ber of cycles behave in relat ion t o each ot her.
For now you do not need t o worry about com plex waveform s and any ot her fact ors regarding
waveform s as we will deal wit h t hem as we go along, at your pace, t hat way you do not feel as
if t here is t oo m uch inform at ion t o learn.
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This is m eant t o be fun so let ’s keep it t hat way
The final m ost im port ant com ponent of sound is TI M BRE.
iii. TI M BRE
This is what defines t he t onal qualit y of a sound.
A C4 not e played on a piano and at t he sam e level as a C4 not e played on a saxophone does
not produce t he sam e sound or t im bre. They are bot h t he sam e level and bot h played at C4
but bot h have dist inct ly different sounds or t im bres.
Tim bres are m ade up of waveform s and it is t hese waveform s t hat go t o m ake up t he t onal
qualit y of a sound. This is called t im bre.
This is t he m ain reason why one sound at a cert ain frequency will sound com plet ely different
t o anot her sound at t he sam e frequency.
When you com e t o use EQ you will underst and why we do not have one overall frequency
chart for all sounds.
A fem ale voice at C3 will sound com plet ely different t o a m ale voice at C3 so t he EQ propert ies
will have t o be different as t he t im bres of t he t wo sounds are dist inct ly different .
The first challenge when EQing m usical sounds is in deciding which area of t he frequency
spect rum cor responds t o which elem ent of a sound's t im bre. I f you want t o em phasize t he
at t ack of a bass drum , where should you boost ? Alt ernat ively, if your vocals sound boxy,
where can you cut or boost m ost effect ively?
This area is called t he ba n dw idt h , t he area at which you want t o boost or cut .
I t is also im port ant t o not e t hat we hum ans have a hearing range of bet ween 20 Hz t o 20 kHz.
To be honest , anyt hing at t he 20 Hz level is felt m ore t han heard. This is why producer s
cleverly add lower frequencies t o a t rack for t hat big club feel.
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5 . Fu n da m e n t a ls a n d H a r m on ics
One t hing t hat can help a lit t le in deciding t his is t o know what frequencies correspond t o t he
fu n da m e n t a ls of each m usical pit ch. For a st art , t his allows you t o define t he lower lim it of
t he range of frequencies generat ed by pit ched sounds.
Let ’s t alk a lit t le about H a r m on ics.
First , t he em ot ional definit ion or descript ion:
All m usical t ones have a com plex waveform , m ade up from loads of different frequencies.
All sounds ar e form ed using a com binat ion of sine waves at varying frequencies and
am plit udes.
Now it get s a t ouch m ore involved. I f we look at t he frequencies of a com plex waveform , t hen
t he lowest frequency is called t he fu n da m e n t a l fr e qu e n cy .
The fundam ent al frequency det erm ines t he pit ch of t he sound. The higher frequencies are
called ove r t on e s. I f t he overt ones ar e m ult iples of ( x1, x2, x3 et c) t he fundam ent al
frequency t hen t hey are called h a r m on ics. The overt ones or u ppe r pa r t ia ls as som e people
like t o refer t o t hem as, m ust be m ult iples of t he fundam ent al t o be known as harm onics.
These frequencies and t heir am plit udes det erm ine t he t im bre of a sound.
Now, t he sim pler explanat ion:
I f you have a waveform t hat has a fundam ent al frequency of 100 kHz, t hen t he second
harm onic will be 200 kHz and t he t hird harm onic will be 300 kHz and so on……
I f you t hink about t he irregular waveform of noise t hen you will underst and t hat it has no
harm onics. Noise cont ains a wide band of frequencies and it is generally accept ed t hat , at
waveform level, t here are no harm onics as t he waveform is non- repeat ing.
I have found t hat by boost ing sounds below t heir fundam ent al frequency, noise of som e sort is
always int roduced int o t he m ix. I n fact , it is always a good policy t o use a high pass filt er
along wit h t he use of EQ on a sound. I will com e t o t his lat er when dealing wit h m et hods and
t echniques of using EQ.
The concept of harm onics, fundam ent als, overt ones et c seem s daunt ing, but it ’s not . The
above is sim ply t o give you a bet t er and m ore t horough insight int o what sound and all of it ’s
com ponent s are.
I do not expect you t o know all of t he above but if you want t o be m ore proficient at your
vocat ion, t hen it helps t o t ry t o underst and what we have covered here.
However, as we have covered correct ive EQ, albeit briefly, it is also vit al t o underst and t hat
EQ is not only about boost ing and cut t ing frequencies, but also about pe r ce pt ion .
Below is a list wit h approxim at e figures for inst rum ent frequency ranges and t heir
fundam ent als. As I said earlier, I do not like list s t hat purport t o be an accurat e frequency
range t able for varying inst rum ent s, due t o t heir inaccuracy. However, t his list is sim ply t o
help you underst and t he fundam ent al and harm onic frequencies of a select ion of inst rum ent s.
I am only list ing t he t ypes of sounds t hat I feel will be used in m ost m odern recordings for
popular m usic, so have om it t ed t he orchest ral and acoust ic inst rum ent s.
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I n st r u m e n t
Kick Drum
Snare Drum
Cym bal
Acoust ic Bass
Elect ric Bass
Acoust ic Guit ar
Elect ric Guit ar
Piano
Bass Voice
Alt o Voice
Soprano Voice
Fu n da m e n t a ls
30- 145 Hz
100- 200 Hz
300- 580 Hz
40- 295 Hz
40- 300 Hz
82- 988 Hz
82- 1319 Hz
28- 4196 Hz
87- 392 Hz
175- 698 Hz
247- 1175 Hz
H a r m on ic
1- 6 kHz
1- 20 kHz
1- 15 kHz
1- 5 kHz
1- 7 kHz
1- 15 kHz
1- 15 kHz
5- 8 kHz
1- 12 kHz
2- 12 kHz
2- 12 kHz
The above ar e only guides, and t o be used purely as a reference.
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6 . To Cu t or t o Boost
Anot her com m on problem t hat beginners m ake is t o boost frequencies in a m ix t o t ry t o m ake
it st and out m ore. This is t rue part icularly for drum sounds. The problem here is t hat noise is
also boost ed so what you end up wit h is a noisy sound in t he m ix, which st ands out even m ore
t han int ended. So t he beginner t ries t o com pensat e by boost ing ot her sounds t o at t ain an
even balance. Yep, you guessed it , m ore noise.
The t rue art of EQ is t o cut , not boost .
However, boost ing cert ain frequencies by sm all am ount s can have a dist inct im pact on a m ix.
The t rick is t o know when t o cut and when t o boost .
To be able t o inst inct ively know when t o cut ( roll- off) or boost , you need t o underst and
frequencies. Basses and pads sound gr eat and full on t heir own, but com bine t hem in a m ix
and t hey st art t o sound m uddy. This is because t hey share so m any of t he lower frequencies.
By cut t ing a cert ain range of frequencies from eit her or bot h, you will, in effect , give t he
percept ion of boost ing t he lower end, or upper end if you are cut t ing t he lower frequencies. I t
always helps t o cut cert ain frequencies wit h t he aim of accent uat ing ot her frequencies. This is
t he Art .
Why?
Because t he individual sounds sound clear and balanced, inst ead of m uddy and biased. By
t aking away, we give. By boost ing t oo m any frequencies and channels, we com prom ise t he
headroom of t he dynam ic range of t he audio. Whet her it is in a m ixer or DAW syst em , boost
t oo m uch and you ent er clipping and dist ort ion t errit ory.
The one area t hat is always t he hardest t o learn is t he m id- end. So m any sounds share t his
frequency spect rum t hat it can lead t o confusion when it com es t o finding a good balance of
frequencies in a m ix.
This is why cut t ing or boost ing sm all am ount s around dist inct fr equency spect rum s of
individual sounds can be so m uch m ore effect ive t han choosing an overall frequency range for
a num ber of sounds and alt ering t hat .
The sam e is t rue of t he whole m ix it self. EQ can be used t o alt er t he apparent loudness of a
m ix, a t echnique com m only used by m ast ering houses.
Our hearing syst em 's frequency response changes w it h loudness. I t is im port ant t o m onit or at
a realist ic and sensible volum e when applying EQ, because t he perceived effect m ay be quit e
different at higher or lower list ening levels.
However, t he fact t hat t he ear get s m ore sensit ive t o high and low frequencies t he higher t he
int ensit y of t he sound, m eans t hat t he brain t ends t o int erpret any sound which is
com parat ively rich in t hese frequencies as loud.
Therefore, if you want m usic t o sound louder at low list ening levels, t hen it m akes sense t o
boost at t he ext rem es of t he frequency range. This is what som e hi- fi syst em s do when t he
Boost or Loudness but t on is used.
I n m ost playback syst em s, you will see what is referred t o as t he ‘sm ile’ curve on graphic EQs.
The sm ile shape denot es t hat t here is a dip in t he m id frequencies and sm all boost s in t he
ext rem e frequencies. Always be aware as t o t he difference bet ween act ual and perceived.
14
I t is also t rue t o st at e t hat at low list ening levels, t he hum an hearing syst em encount ers
difficult ies hearing very low and very high frequencies.
This is called t he Flet cher Munson Effect .
I n t his inst ance, EQ is used t o cut and boost select ed frequencies, so t hat a m ore balanced
gain st ruct ure is kept right t hroughout t he hearing spect rum at low list ening levels.
Masking is anot her problem t hat can be t reat ed wit h sensible use of EQ.
How m any t im es have you used a sound, t hat on it ’s own sounds excellent , but placed
alongside anot her sound, get s swallowed up by t he second sound?
This happens because t he t wo sounds have very sim ilar frequencies, so one ‘m asks’, or hides,
t he ot her sound. This result s in t he m asked sound sounding dull, or j ust sim ply unheard. EQ is
a very good t ool t o use in t hese inst ances. By cut t ing away cert ain frequencies from one of t he
sounds, you will invariably expose and boost t he frequencies of t he ot her sound, t hus
accom plishing separat ion and dist inct ion bet ween t he t wo sounds.
Anot her pit fall t hat m ost beginners and som e pros fall int o is what I call t he EQ Syndrom e.
This happens when a m ix is poorly recorded wit h lit t le separat ion in t he sounds and EQ is used
t o t ry t o ‘separat e’ and ‘cleanse’ t he sounds. This always result s in a brit t le m ix wit h individual
sound com ponent s sounding as if t hey do not belong t oget her. Anot her exam ple of t his EQ
Syndrom e is when an engineer or producer feels t hat t hey have t o EQ every channel t o gain a
st am p on t heir ‘feel’. This com plaint is quit e com m on in cert ain Hip Hop and Rap songs
whereby t he drive ( drum beat and bass line) of t he song sounds separat e from t he vocals.
This can act ually be a good t hing, if t he effect is int ended, but t he ear begins t o at t une it self t o
t he separat e frequency bands inst ead of a rich t apest ry of frequencies, and t he song t hen
st art s t o ‘t ire’ t he list ener.
I n t hese inst ances it is cr ucial t o have a clean and balanced recor ding, so t hat t he EQ process
can be creat ive as opposed t o correct iv e. You should st rive t o record t he source sound
elem ent s at near enough t he frequencies t hat you will event ually release. That way you will
only need t o m ake m inor adj ust m ent s inst ead of sweeping corr ect ions.
The added advant age of a clean and balanced recording, wit h em phasis on t he correct source
frequencies, is t hat you can always com e back and rem ix t he ent ire recording off a blank
palet t e. The recording will never t ire it self and never be const rict ed in t erm s of frequencies.
This will always allow for refreshing rem ixes.
EQ has m any guises.
We use correct ive EQ in edit ing suit es and product ion houses t o isolat e and dim inish a
frequency or sound, t o accent uat e or elevate a part icular sound, frequency or recording.
Classic cases are t hat of broadcast engineers having t o isolat e t he narrat ive or spoken part
am idst a plet hora of ot her background noises, or t o sim ply rem ove a click or unwant ed sound,
and, even m ore com m only, t o alt er t he spoken par t t o sound m ore pleasing in t he event t hat
it is harsh sounding. The lat t er is m ore in t he dom ain of creat ive or m usical EQ.
Using EQ as a t ool t o separat e t racks is anot her favourit e of producers.
This is act ually quit e an im port ant procedure, but one t hat does need a careful approach.
I t is im perat ive t hat your recordings ar e as clean as possible and have a perfect S/ N rat io. This
will ensure t hat sm all am ount s of EQ boost , on select ive frequencies, will at t ain t he best
result s.
15
A lot of beginners m ake t he m ist ake of poorly recording t he source m at erial and t hen using EQ
t o t ry t o separat e and boost t he gains of t he recorded t racks.
Separat ion can only be t rut hfully affect ed if t here is a clear dist inct ion bet ween frequencies, so
t hat you only need t o isolat e sm all frequency ranges and apply nom inal boost s. Having a
m uddy m ix of low end inst rum ent s m akes for having t o perform som e ext rem e cut s/ boost s,
and t his will be m ore dest ruct ive t han creat ive.
Dist ance has a dram at ic effect on sound.
High frequency sounds are da m pe n e d and absorbed by t he frict ion of air, so t hey sound
quiet er or furt her away.
The furt her t he sound t ravels, t he m ore it is dam pened.
We can m im ic t his in a m ix by cut t ing backing vocals at , for exam ple, t he 10 kHz range, t hus
m aking it sit back in t he m ix and in t urn bringing out t he lead vocals t o t he front of t he m ix.
Percept ion gained by clever use of EQ.
I t t hen follows t hat if you dam pen a sound, you will invariable give it t he percept ion of being
furt her away or quiet er.
Use t his piece of inform at ion.
I f you need t o bring a sound down in a m ix, som et im es all it needs is t o have t he t op
frequencies rolled off.
The sam e t hinking can be applied when you want t o bring a sound out in a m ix. I nst ead of
boost ing t he gain of t he whole sound, it can be very effect ive t o boost som e of t he higher
frequencies. But , rem em ber t hat we are t alking about very sm all changes her e, not huge knob
t urns.
Anot her area of separat ion t hat is very im port ant is t hat of redundant frequencies. This is m y
very flash way of saying ‘frequencies t hat are not needed’.
You will find t hat t here ar e a lot of inst rum ent s t hat share low frequencies, not j ust basses and
kick drum s. So, rem oving predefined low frequency ranges from som e of t he low end
inst rum ent s in your m ix can act ually separat e and define t he low frequencies even m ore.
Recording your t racks rich in frequencies allows you t he scope t o cut or boost any frequency
range, as it already exist s in t he recorded audio. I cannot t his enough.
Separat ing t he frequencies of inst rum ent s by t he use of EQ is a t radit ional, yet subt le, m et hod
of creat ive and correct ive EQ.
Creat ive EQ is an art form in it self.
Exam ples of t his would ent ail, bringing out t he best in a lead vocal line and yet keeping it
balanced wit h t he backing vocals, or t o m ix t he drive elem ent of a t rack t o it ’s opt im um club
feel, or sim ply t o use coloured EQs t o add t o or alt er an exist ing sound. The list is endless. You
are only lim it ed by your knowledge on t he subj ect , and, of course, having an ear helps, but
t his is not a pre requisit e.
Finally, we use EQ at t he m ast ering st age t o best represent t he final st ereo m ix for it ’s genre
and m edium . Once all t he elem ent s are in place and a m ix of t he session is handed t o t he
m ast ering house, t he real t reat m ent t akes place t o bring out t he best in t he final m ix and t o
m ake sure t hat t here is a good dynam ic range and all t he elem ent s are in place for what ever
t he m arket t he m ix is aim ed at .
We have also arrived int o t he preset based EQ world for m ost hi- fi owners.
16
I n fact , t his has got t o t he point whereby hi- fi m anufact urers put preset EQ set t ings on t heir
syst em s for t he list ener t o choose from . Ghast ly preset s called Pop, Am bient , Disco et c. are
predefined EQ t em plat es t hat you can t weak t o your heart ’s cont ent .
A well m ast ered m ix will not need any addit ional EQ m anipulat ing at t he list ening st age, as
good m ast ering houses will t reat t he signal for opt im um use on all list ening m edium s.
A good m ast ering house/ engineer can m ake or break your t rack in t he com m ercial vein. Their
m ost valued weapon: EQ.
So, we now underst and how im port ant EQ is and t he fundam ent al uses it m ight have, but we
have not delved int o t he different t ype of EQ available.
17
7 . Te r m in ology a n d de fin it ion s- Filt e r s
To furt her underst and t he t erm inology used in t his E- book, I feel it is essent ial t hat you
underst and t he following:
Cu t - off fr e qu e n cy
This is t he point ( frequency) at which t he filt er begins t o filt er ( block or cut out ) . The filt er will
lower t he volum e of t he frequencies above or below t he cut - off frequency depending on t he
t ype of filt er used.
At t e n u a t ion
This ‘lowering of t he volum e of t he frequencies,’ is called At t e n u a t ion . I n t he case of a low
pass filt er, t he frequencies above t he cut off are at t enuat ed. I n t he case of a high pass filt er,
t he frequencies below t he cut off are at t enuat ed.
Re son a n ce
Boost ing t he narrow band of frequencies at t he cut - off point is called resonance. Also know as
Q and bandw idt h, in effect , he higher t he resonance, t he narrower t he bandwidt h.
A very cool way of underst anding what resonance sounds like is t o perform what we call a
‘sw e e p’. Yes, anot her flash and funky t erm we progr am m ers use t o explain som et hing really
sim ple.
Sweeping t he filt er m eans m anually t urning t he resonance knob, clockwise and ant i- clockwise.
Select a waveform , set t he cut - off point and t urn t he resonance knob and list en
t o t he result s. As you are sweeping, t he resonance goes t hrough all t he different frequency
harm onics, of t he waveform , and boost s/ cut s t hem , at t he cut - off point .
Q
Also known as ‘w idt h of t h e filt e r r e spon se ’, t his is t he ‘ce n t r e fr e qu e n cy ’ of t he
bandwidt h and is m easured in Hz. Also know as bandwidt h and resonance.
A high Q value denot es a narrow filt er widt h ( bandwidt h) . A low Q value denot es a wide filt er
widt h ( bandwidt h) .
This is act ually a very im port ant piece of inform at ion because wit h t he Q cont rol alone, you
can m ake your audio sound high and brit t le or warm and m usical. This does not m ean t hat
18
you m ust use low Q values all t he t im e, in t he hope of at t aining warm t h, but you m ust
underst and what frequencies need filt ering. I f your int ent is t o use EQ as a m usical t ool, t hen
be aware of what t he Q value can do t o audio. For creat ive EQ, t his is a weapon oft en ignored.
19
8 . Type s of EQ
To begin t o underst and t he EQ, we need t o first define t he t wo cat egories it falls in, Pa ssive
a nd Act ive .
Pa ssive EQs
These t ypes of EQs have t he dist inct ion of being ext rem ely sim ple in design and, m ore
im port ant ly, t hey cannot boost frequencies, only cut . The way t hey work is act ually very m uch
t o do wit h percept ion.
By cut t ing, for exam ple, low frequencies ( bass) , t hey m ake t he m id and high frequencies
sound ‘louder’.
Passive EQs do have t heir uses. Alt hough t hey are inflexible, t hey can perform reduct ion t asks
reasonably well. By cut t ing high frequencies, t hey are able t o cut or lower hiss ( high frequency
noise) . However, by t heir very nat ure, passive EQs, or filt ers, have t o t hen have t he signal
boost ed t o com pensat e for t he cut . This, in it self, int roduces noise int o t he signal pat h. The
noise com ing from t he am p used t o boost t he signal.
Act ive EQs
Because of t he lim it at ions of passive EQs, m ost EQs are built around act ive filt er circuit s which
use frequency select ive com ponent s, t oget her wit h a low noise am plifier.
And it is t his t ype of EQ t hat we are now going t o concent rat e on.
Fix e d Fr e que n cy EQ
Pret t y self explanat ory, t his EQ allows cut / boost of one or m ore frequencies. There are no
addit ional cont rols over t he usual com ponent s, like bandwidt h, Q, et c.
Pe a k in g EQ
A peaking EQ is an EQ which boost s a specific band of frequencies.
Whereas a shelving filt er has a shelf like curve, t his filt er has a bell shaped curve. The Q
set t ing det er m ines t he widt h of t he bell, while boost or cut det er m ines t he height or dept h of
t he bell.
Tw o Ba n d or Th r e e Ba n d
These t ypes of EQ sim ply have t wo or t hree separat e frequency ranges. Usually denot ed as
low, m id and high, t hese bands can only be cut or boost ed.
Sh e lvin g Filt e r / EQ
We have t ouched on t he use of t one cont rols t hat are form s of EQ. These cont rols cont rol a
t ype of filt er t hat is called a sh e lvin g filt er. I n t he case of t he bass and t reble knobs, low pass
and high pass shelving filt ers are used respect ively.
A low- pass shelving filt er passes all frequencies below it s cut - off frequency, but a t t e n u a t e s
all frequencies above it s cut - off frequency. Sim ilarly, a high- pass filt er passes all frequencies
above it s cut - off frequency, but affect s all frequencies below it s cut - off frequency.
This is t he sim plest t ype of act ive EQ. This EQ can shape response in a num ber of ways:
boost / cut low frequencies, boost / cut high frequencies. This is why I have included t he graph t o
dem onst rat e what happens wit h t he filt ers, low and high pass, in t his t ype of EQ.
20
Most m ixers will allow for low and high frequency EQ, and in t he case of shelving filt ers, t heir
m id frequencies are usually fixed.
I t is also com m on for t he filt er slope t o be 6 dB per oct ave. This allows for a gent ler effect .
The shape is shelf like, so t he boost or cut is progressive over a range. Filt ers do not have a
no- effect at a frequency and t hen inst ant ly j um p and suddenly reappear at t he next
frequency. They have t o get t here som ehow. The way, and by how m uch, t hey get t here is
called t he gr a die n t or slope . I n t he case of t he shelving filt er, t he m ost com m on slope is 6
dB gain change per oct av e ( doubling of t he frequency) . I t t akes t im e for t he filt er t o at t enuat e
frequencies, in proport ion t o t he dist ance from t he cut - off point . This is t he slope .
The diagram below illust rat es what happens if you cut or boost frequencies in a low- pass and
a hi- pass filt er.
Low Pa ss
H igh Pa ss
Blue = Boost
Red = Cut
Gr a ph ic EQ
A graphic equalizer is sim ply a set of filt ers, each wit h a fixed cent re frequency t hat cannot be
changed.
The only cont rol you have is t he am ount of boost cut or in each frequency band. This boost or
cut is m ost oft en cont rolled wit h sliders. The sliders are a graphic represent at ion of t he
frequency response, hence t he nam e 'graphic' equalizer.
The m ore frequency bands you have, t he m ore cont rol and accuracy you have over t he
frequency response.
Mixing consoles rarely have graphic EQs, but PA m ixers oft en have a st ereo gr aphic EQ for
EQing t he final st ereo out put .
A graphic equalizer uses a set of ba n d- pa ss filt ers t hat are designed t o com plet ely isolat e
cert ain frequency bands.
The diagram below shows t he frequency response of a band- pass filt er.
21
Ba n d Pa ss Filt e r
A filt er t hat passes frequencies bet ween t wo lim it s is known as a ba n d- pa ss filt e r .
This is a great filt er. I t at t enuat es frequencies below and above t he cut - off and leaves t he
frequencies at t he cut - off. I t is, in effect , a low pass and a high pass t oget her. The cool t hing
about t his filt er is t hat you can elim inat e t he lower and higher frequencies and be left wit h a
band of frequencies t hat you can t hen use as eit her an effect , as in having t hat real m id range
t ype of old radio sound, or use it for isolat ing a narrow band of frequencies in recordings t hat
have t oo m uch low and high end.
Try t his filt er on synt hesizer sounds and you will com e up wit h som e wacky sounds. I t really is
a useful filt er and if you can run m ore t han one at a t im e, and select different cut - offs for each
one, t hen you will get even m ore int erest ing result s. I nt erest ingly enough, band pass filt ering
is used on form ant filt ers t hat you find on so m any soft synt hs, plugins, synt hesizers and
sam plers. Em u are known for som e of t heir form at filt ers and t he t echnology is based around
band pass filt ers.
I t is also good for t hinning out sounds and can be used on percussive sounds as well as
creat ing effect s t ype of sounds.
I oft en get em ails from program m ers want ing t o know how t hey can get t hat old radio effect
or t elephone line chat effect or even NASA space dialogue from space t o Houst on. Well, t his is
one of t he t ools. Use it and experim ent .
You will enj oy t his one.
N ot ch Filt e r – a lso k n ow a s Ba n d Re j e ct Filt e r
The inverse of a band pass is t he not ch filt er.
This is a very pot ent EQ/ filt er. I t can hom e in on a single frequency band, and cut / boost it .
Used specifically for ‘problem ’ frequencies, t he not ch can be one of t he m ost useful filt ers.
This is t he exact opposit e of t he band pass filt er. I t allows frequencies below and above t he
cut - off and at t enuat es t he frequencies around t he cut - off point .
Why is t his good?
Well, it elim inat es a narrow band of frequencies, t he frequencies around t he cut - off, so, t hat in
it self is a great t ool. You can use t his on all sounds and can have a dist inct effect on a sound,
not only in t erm s of elim inat ing t he frequencies t hat you want elim inat ed, but also in t erm s of
creat ing a new flavour t o a sound.
But it s real pot ency is in elim inat ing frequencies you don’t want . Because you select t he cut off point , in essence, you are select ing t he frequencies around t hat cut - off point and
elim inat ing t hem .
An invaluable t ool when you want t o hone in on a band of frequencies locat ed, for exam ple,
right in t he m iddle of a sound or recording. I som et im es use a not ch filt er on drum sounds
22
t hat have a m uddy or heavy m id sect ion, or on sounds t hat have a lit t le noise or frequency
clash in t he m id sect ion of a sound.
Pa r a m e t r ic
This filt er cont rols t hree param et ers, frequency, bandwidt h and gain. You select t he range of
frequencies you want t o boost or cut , you select t he widt h of t hat range and use t he gain t o
boost or cut t he frequencies, wit hin t he select ed bandwidt h, by a select ed am ount .
The frequencies not in t he bandwidt h are not alt ered. I f you widen t he bandwidt h t o t he lim it
of t he upper and lower frequencies ranges t hen t his is called shelving. Most param et ric filt ers
have shelving param et ers.
Param et ric filt ers are great for m ore com plex filt ering j obs and can be used t o creat e real
dynam ic effect s because t hey can at t enuat e or boost any range of frequencies.
Basically, t he param et ric EQ places several act ive filt ers across t he frequency spect rum . Each
filt er is designat ed t o a frequency range, low, m id, high et c. You have t he usual cut / boost ,
resonant frequency and bandwidt h. I t is t hese qualit ies and t he cont rol over t hem t hat places
t his part icular EQ in t he producer’s arsenal of dynam ic t ools, and m akes it det ailed and
versat ile.
However, you need t o underst and what you are doing when using a param et r ic EQ, ot herwise
t hings can go very wrong.
Underst and frequencies and sound, and you will be in t ot al cont rol.
Qu a si- pa r a m e t r ic EQ
This is j ust anot her form of param et ric EQ but wit hout t he bandwidt h cont rol.
Sw e e p EQ
This is very sim ilar t o a band pass filt er, but wit h variable cent re frequency, and no cont rol
over t he widt h of t he filt er response ( Q) .
You will find t hat m ost m ixers will have band pass EQ, and som e will have sweep EQ ( where
t he cent re frequency can be varied, also known as ‘t u n e a ble ’) , but very few, m ainly digit al,
will have param et ric EQ.
Pa r a gr a ph ic EQ
Anot her variat ion on t he graphic EQ. This EQ provides cont rol over t he cent re frequency of
each band.
23
9 . Ph a se t h e bi- pr odu ct
A very im port ant aspect of EQ, in relat ion t o affect ed and non- affect ed frequencies, is t hat of
phase.
We know t hat affect ing t he frequencies t hat we have chosen for equalisat ion, also affect s t he
phase of t hose select ed frequencies, in relat ion t o t he unaffect ed frequencies. The process
it self also affect s t he frequency response of t he signal being t reat ed. We are t alking about t iny
offset s here. Every t im e a frequency range is select ed and t reat ed, t he affect ed frequencies
will exhibit displacem ent , in relat ion t o t he unaffect ed frequencies. This offset is phase.
Whereas we are not t alking about big swirling phase effect s, as in guit ar phasing, we are,
however, t alking about t he pure definit ion of phase. This is probably not som et hing t hat you
will hear as phase, but it is som et hing t hat affect s our percept ion of t he t reat ed frequencies.
Depending on t he nat ure of t he displacem ent , we perceive t he t r eat ed frequencies as dist ance.
Why is t his im port ant ?
This is what different iat es t he t onal charact erist ics of analogue hardware and digit al soft ware
EQs.
The analogue EQ unit will exhibit far m ore m usical phase changes t han it ’s digit al count erpart ,
and at very low gains, whereas t he digit al EQ unit will have t he advant age of leaving t he
phase relat ionships hardly affect ed, t hus allowing for m ore robust gain changes.
They bot h have t heir uses.
24
1 0 . Le t I t Be gin
We have covered EQ as a subj ect . I t is now t im e t o begin wit h walk t hrough exam ples.
The following exam ples will deal wit h inst rum ent s and vocals. This way, we have a good
variet y of scenarios t o deal wit h, and a good range of frequencies t o cover and m anipulat e.
Drum s – Kick
Fig 1
List en t o t his file ( K0 2 0 )
As you can see from t he above im age ( Fig 1 ) , I have opened up a kick file in Sound Forge. We
are now going t o m anipulat e t his file and creat e new files, by t he sim ple use of EQ.
However, before we perfor m any t ype of m anipulat ion, I want t o show you how t o evaluat e
and see t he frequency spect rum ( range) of any select ed audio file.
For t his, we use a piece of soft ware, or hardware, called a spect r um analyser.
Sound Forge has t his t ool under t he m enu opt ion, Tools - Spect rum Analyser.
The im age below ( Fig 2 ) , clearly displays t he frequency spect rum of t he kick when played.
25
Fig 2
By using t he analyser we are able t o fully see t he frequency st ar t , t he frequency body and t he
frequency t ail- off.
This t ype of t ool is invaluable in helping us t o apply EQ.
You will appreciat e how useful t his t ool is when we com e t o rem oving unwant ed frequencies,
or when we com e t o using EQ t o eit her correct flawed vocals, or t hin out or t hicken vocal lines.
The Y axis ( left hand side figures) denot es am plit ude/ level in dB.
The X axis ( bot t om figures) denot es t he frequency in Hz.
The analyser t ells us t hat t his kick st art s on a frequency of 20 Hz at – 45 dB ( at t ack) , rises t o
65 Hz at - 36 dB ( height of at t ack’s decay) , drops t o and levels off at around 88 dB.
This helps us a great deal in underst anding t he charact erist ic and shape of t he kick file and
t his in t urn gives us a det ailed num erical and graphical reference for set t ing up our EQ
param et ers.
What did I j ust say, in English?
Sim ple: check t he sam e im age but zoom ed in ( Fig 3 )
26
Fig 3
I highlight ed t he peak of t he kick file’s waveform wit h t he m ouse and it gave m e t he figure
above.
I can m ove m y m ouse over any part of t he waveform and it will highlight t he dat a I need.
Wit h t his exam ple, I can now decide what t ype of EQ I want t o apply and by how m uch.
The punch com ponent , or at t ack, of m ost bass drum s lies bet ween about 60 and 110Hz. This
is where you find t he low- end ener gy of m ost kicks. Below t his range, you'll m ost ly feel, rat her
t han hear, any boost , and it 's easy t o eit her neglect t his and be left wit h all sort s of frequency
im balances in you
EQ
By Eddie Ba zil, Sa m ple cr a ze .com
This book and it s cont ent s are © 2005 Sam plecraze.com . All right s
reserved. Unaut horised copying, re- selling or re- product ion of t his
book or any aspect of t his book is st rict ly forbidden.
Con t e n t s
i. How t o use t his book
1 . I nt roduct ion t o Equalisat ion
2 . Sound
3 . Com ponent s of Sound
4 . Midi and Frequency Chart
5 . Fundam ent als and Harm onics
6 . To Cut or t o Boost
7 . Term inology and definit ions- Filt ers
8 . Type of EQ
9 . Phase t he bi- product
1 0 . Let it begin – Drum s – Kick
1 1 . Snare
1 2 . Drum Loops
1 3 . Voice
1 4 . Prim ary and Secondary EQ
1 5 . Voice Exam ples – Double Tracking
1 6 . Voice EQ Addit ional Exam ples
1 7 . Mixing EQ – Gospel
1 8 . Mixing EQ – Exam ples
1 9 . Final Word
2
i. H ow To Use Th is Book
Pr e fa ce – H ow t o Use This Book
Tut orial Files
Many of t he t ut orials in t his book have associat ed files t hat are used t o explain t he concept s
m ore clearly t o you. All t ut orial files are included in t he ‘sounds’ folder t hat cam e wit h t his book and
Make sure you ext ract all t he files correct ly wit hin a program such as Winzip ( w w w .w in zip.com ) .
Searching
The beaut y of a PDF is t hat you can search it s cont ent s very easily from wit hin t he free Abode
Acrobat reader. I recom m end you inst all t he full version ( it ’s st ill free) which is available from
Here
ht t p:/ / w w w .a dobe .com / pr odu ct s/ a cr oba t / r e a dst e p2 .ht m l
To search t his Ebook, sim ply go t o ‘Edit ’ and select ‘Search’. Alt ernat ively, if you have a PC j ust
press ‘CTRL & F’.
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1 . I n t r odu ct ion t o Equ a lisa t ion
Alm ost every forum I visit , or every 1 in 5 em ails I receive, t he subj ect m at t er t hat is m ost
discussed is EQ ( equalisat ion) .
What it is, how t o use it and when t o use, which one t o use and which is t he best for t he given
t ask and, m ost im port ant ly, what frequencies cover cert ain sounds. Everyone is aft er a quick
form ula.
What m ost people do not realise is t hat EQ is one of t he m ost powerful t ools available t o a
producer, and m ast ering house, and t o m ast er t his t ool one needs t o underst and frequencies.
When t he t erm 'EQ' ( equalisat ion) is m ent ioned, people invariably t hink of t he t one cont rols on
t heir hi- fi syst em s. Knowing t his act ually gives you a head st art . The fact t hat a sound can be
m ade warm er or punchier already gives you an idea as t o what EQ is. You know t hat by
t urning t he t reble knob up on your hi- fi m akes t he sound bright er, t urning it down m akes t he
sound less bright and m ore fluffy or woollen.
What you are act ually doing is boost ing, when you t urn t he knob ‘up’, and cut t ing, when you
t urn t he knob ‘down’, t he predet erm ined frequencies t hat are assigned t o t hat knob.
Before we get deep int o EQ, let us look back a t ad at why EQ was int roduced int o our lives in
t he first place.
H ow a n d W h y
This whole headache began in t he broadcast ing field. Blam e t hose guys.
Act ually t he first ever inst ances of equalisat ion was in t he com m unicat ions indust ry. EQ was
used t o count eract som e of t he problem s in t elephone syst em s.
Tone cont rols were creat ed and used t o com pensat e t echnical inaccuracies in t he recording
chain, m ore not ably, com pensat ing for m icrophone colourat ion and room acoust ics. EQ was
used as a m eans of cont rolling t he gain of a range of frequencies.
I n t hose days, a st andard, bass, m iddle and t reble gain cont rol were all we had. Today, we are
act ually spoilt for choice as t here are so m any param et ers t hat we can cont rol on any t ype of
EQ, t hat it has act ually becom e confusing.
From correct ive EQ, we have com e a long way, t o creat ive EQ.
I do not want t o bore you wit h t he hist ory of EQ or who invent ed what . You can t rawl t he net
for som e excellent art icles on t his subj ect . What I want t o do is t o dive in and get you st art ed
on t his det ailed and confusing subj ect .
However, before I get int o t his deeper, I need you t o underst and ‘sound’ and ‘frequencies’.
Those t hat have read m y t ut orials on m y websit e ht t p: / / www.sam plecraze.com will know t hat
I have covered t he subj ect of sound in det ail. For t hose who cannot be bot hered t o read t hose
t ut orials, here is t he condensed version:
To underst and any part of EQ you need t o underst and sound, what it is, how it m oves, how we
perceive it and why we perceive it t he way we do.
Once you underst and t his t hen shaping it or m anipulat ing it becom es so m uch easier.
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Ta ggin g
The m et hod I am going t o use t o help you in underst anding t he t erm inology and definit ions
and what each part is and does is a syst em t hat has exist ed for cent uries and works ext rem ely
well in every aspect of your life.
I t is a syst em t hat speed reading specialist s, m em ory recall cent res and even high powered
execut ive t raining program s use. I t is called ‘Ta ggin g’ or ‘Lin k in g’. I t is t he sim plest and
m ost effect ive ‘rem em bering’ t ool.
You have used it since you were a child. Every t im e you were asked t o draw a house in a field,
you would draw a st rong big house on green grass wit h a huge sun t hat was always yellow,
red or orange wit h a t ree and a cow. Of course som e people drew t he sam e t opic in t he
Picasso m ould or surreal a la Dali, but on t he whole, t he pict ure is alm ost always t he sam e.
Why? Because we rem em ber t hings t hat have an effect on our senses, be it t ouch, sm ell,
t ast e, hearing or visual. The st rong colour of t he sun and t he size of it are a great way of
rem em bering what a sun looks like. The big house in t he cent re of t he drawing will always
st ay in your m ind. The cow is always alone and st rongly accent uat ed and is always t ot ally out
of size in com parison t o t he house. The ground is always green grass and t he sky always blue
and if t here is a cloud t hen it is always one big round cloud.
These im ages are st rong and always st ay in m em ory. The sam e t echnique is used in t agging.
We creat e an im age rich in as m any of t he senses as possible and t hat will always st ay in our
m inds, far st ronger t han having t o learn t hings in parrot fashion.
I have used t his t echnique all m y life and now do it unconsciously. Not only does it work but it
is also fun as t he t ool for t agging is your im aginat ion and not hing is st ronger or st ays longer in
your m em ory t han an im age creat ed out of your im aginat ion.
Probably by now you feel t hat I require a great deal of help and t hat t here are cert ain places
for people like m e, com fort able places t hat offer 24 hour securit y and in dept h t reat m ent . You
are probably right but not for t he reasons for t his t ut orial.
So, let us begin t his j ourney.
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2 . Sound
Sound is t he displacem ent of air around t he source and how we perceive t hat displacem ent .
Right , what does t hat m ean?
Think of t he best and m ost com m only used analogy: t hat of dropping a st one in a pond and
wat ching t he ripples form . The ripples always m ove away from where t he st one m eet s t he
wat er ( source) . The air displacem ent is t he ripples creat ed by t he dropping st one. I n t his case
we see t he ripples. I n t he case of sound we hear t he ripples ( t he displaced air) .
How do we hear t he displaced air?
Our eardrum s pick up t he displaced air and our brains t hen process t he dat a as sound. I could
go int o t he det ails about t he ear m uscle vibrat ing and t he eardr um being a cham ber and on
and on and on…but t hat is not what you want t o know.
The t agging im age here is t he r ipple .
Has it ever occurred t o you t hat when a pict ure is drawn of a guit ar am plifier, wit h a guit arist
playing loudly, you always see a few arced lines drawn com ing out of t he am plifier?
Exact ly like t he ripples in t he pond. I n fact t his im age is always t he sam e for speakers t hat are
playing m usic. The pict ure or t ag here is, again, always t he sam e wit h arced lines st art ing as
sm all arcs growing t o large arcs and away from t he speaker.
Keep t hat im age in your head and t hat const it ut es sound, or m ore precisely, sound waves, like
t he ripples.
Fig 1 illust rat es t his. I have deliberat ely used freehand so it will m ake you laugh and st ay in
your m em ory.
Fig 1
SOUN D W AVES
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3 . Com pon e n t s of Sou n d
Now let s us look at t he com ponent s t hat m ake up sound.
There are t h r e e , and are really quit e sim ple t o underst and if you apply t he ripple analogy.
The displacem ent of air or air pressure as is m ore com m only known, creat es t he waves in fig
1 and is know as Sound Waves. The rat e at which t hese waves occur is called Fr e que n cy.
So our first com ponent of sound is Fr e qu e n cy.
i. FREQUEN CY
This is sim ply calculat ed at how m any cycle s ( waves) occur every second. These cycles are
repeat ed so really we only need t o look at how m any cycles ( waves) occur in one second.
The result is m easured as cycles/ second and t his unit of frequency is called a Hert z and t he
abbreviat ion is Hz.
You cannot get sim pler t han t hat …..how m any cycles hit you in one second.
Heinrich Hert z was a dude who worked wit h wavelengt hs and frequency, so we have t o t hank
t he m an and it seem ed only right t o nam e t his lit t le calculat ion aft er him . I always rem em ber
t he rent - a–car agency when I t hink of frequencies and Hert z and it m akes m e sm ile every
t im e so rem em bering t hat nam e is easy.
To give you an exam ple of how easy t his is check out t he following:
I f you had 50 cycles hit you in one sec t hen t hat would be a 50 Hz wave. There, sim ple and
m akes you look cool in t he bar when you want t o im press som eone…or m aybe not .
So it also follows and m akes com plet e sense t hat if you had 10,000 cycles per second t hen
t hat would be 10,000 Hz, but , because we don’t want t o have t o writ e so m any num bers every
t im e a t housand appears we use t he k let t er t o m ean a t housand.
So, 10,000 Hz is now writ t en as 10 kHz. Now you look even cooler. There is a reason we do
t his and it ’s not because we want t o look deep and com plicat ed individuals but sim ply because
of all t he work t hat has been carried out on our hearing range in t he past .
And a range was form ed, sure it varies but generally speaking, our hearing range is anywhere
from 20 Hz, deep, t o 20 kHz, high.
Now, let us t hink of t hat range and m ake life a lot easier by giving nam es you recognise t o t he
frequency range.
So: bass, m idrange and t reble are easy t o rem em ber and if you are old enough t hen t hat ’s
about all t hat used t o exist on hi- fi syst em s back in t he days of arm our and j oust ing. Now let
us give t hose t ags a frequency range and t hen all becom es so m uch easier t o underst and.
Bass: 10 Hz t o 200 Hz
Midrange or m id, a t erm you hear a lot of engineers use: 200 Hz t o about 3 kHz.
Treble: 3 kHz t o what ever t he highest value you can hear.
I t is im port ant t o m ent ion, at t his st age, m y beliefs regarding frequency chart s. I am not
t alking about t he cycles chart com ing up in t his t ut orial, but about chart s depict ing ranges of
inst rum ent frequencies.
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I put very lit t le im port ance on frequency chart s for inst rum ent s. Alm ost every websit e you
visit , t hat displays a frequency chart , you will see t hat t hey all vary in t heir ranges. The reason
for t his is quit e sim ple. Ranges can be bot h inaccurat e and broad. I t hink it is a wast e of t im e
displaying chart s, because alm ost every st udent I have t ut ored, t hat has t ried t o use one of
t hese chart s, has st ill ended up request ing help on EQ.
I t is far m ore helpful t o underst and frequencies and sound, t han it is t rying t o use a chart of
t his t ype.
Once you underst and t he cont ent of t his E- book, you won’t need a chart .
I will, of course, give exam ples of cert ain sound frequency ranges and what happens when
you apply cert ain EQ param et ers t o t hem .
So we now know t hat higher frequency sounds are higher in pit ch as t here are m ore cycles per
second and lower frequency sounds have fewer cycles per second. Easy.
Right now I t hink it is im port ant t o show you a frequency chart for all t he not es on a keyboard
or scale and t he m idi not e num bers as well as t his will com e int o play at a lat er dat e when we
deal wit h synt hesis and program m ing wit h t he use of m idi.
You do not need t o learn t his chart in parrot fashion but it is im port ant t o underst and som e of
t he frequencies t hat are used as, lat er, you will need t o know t hese frequencies so t hat if you
need t o use EQ t o shape a sound or rem ove or add cert ain frequencies, t hen t he chart can
prove t o be invaluable
.
I n m ost cases, you only need t o recognise t he m ain frequencies for cert ain not es. For
exam ple: C4 at 261.63 Hz is a great reference point , because t hen you can find, easily, C5 or
C3 et c….
I cannot st ress how im port ant frequencies are for t he underst anding of sound and EQ.
Engineers live by t hem as do producer s and Sound Font developers.
I f t here is one piece of inform at ion t hat overrides any ot her in t erm s of im port ance it is t he
underst anding of frequencies.
How oft en have you t ried t o m ix your t rack only t o be m yst ified by t he result ?
Term s like ‘m uddy’ or ‘t hin’ spring t o m ind and t hese are all because t he m ixer or producer
does not have an underst anding of frequencies and t heir effect on ot her frequencies in a m ix.
Underst and t his basic concept and you will be arm ed wit h t he m ost pot ent weapon.
Waveform s and frequencies go hand in hand.
Underst and t hese t wo and t he rest is all about using t he t ools.
So, let ’s get on wit h t he CH ART
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4 . M idi a nd Fr e qu e n cy Ch a r t
M idi N o
N ot e
Ke yboa r d
Fr e q
As you can see from t he funky chart t hat for every oct ave you go up you double t he frequency
and it is t he sam e in reverse, for every oct ave t hat you go down, you halve t he frequency.
Exam ple: C4 is 261.63 Hz. To get t o C5 we double t he frequency so it is now 523.25 Hz. And
if we want ed t o go from C4 t o C3, it would be 130.81 Hz. There, a few secret s t o t hrow about .
Now let us creat e t he t ag for t his whole sound t hing.
I always im agine a wave as a 3 dim ensional ent it y and wit h t hat I at t ach colours and size. So,
for a low frequency wave I will t hink of it as a large and flowing wave wit h nice warm colours
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like orange or deep red and t he whole im age is nice and slow. For higher frequencies I use
sm aller and fast er waves and in harder colours like bright yellow or st riking blue. This im age is
t hen enhanced furt her by having a person st anding in front of t he waves, usually m e, but m y
nam e is Hert z and I am list ening t o t hese waves in a rent a car. Alt hough t his m ay now
confirm t he urgency for m e t o seek t herapeut ic help, it is t he best way for m e t o rem em ber
t hings.
You can creat e what ever im ages or st ory lines t o t he definit ions in t his t ut orial. They are your
im ages and m ust work for you.
Next on t he sound m enu is Am plit u de :
ii. AM PLI TUD E
Generally speaking t his m eans t he loudness or level of a sound or w a ve for m .
I prefer t he word w a ve for m for sound as it is t he form or shape t hat t he waves t ake and t he
furt her we go int o t his t ut orial t he m ore t hat t erm will m ake sense as waveform s vary in
shape and charact er so, from now on, I want you t o use t he word w a ve for m for sound.
I t is bet t er defined wit h a sim ple graph. I n fact , now is as good a t im e as any t o int roduce
you t o graphs. Ent er fig 2 .
Fig 2
As you can see, t he waveform , it ’s act ually a sine wave but don’t worry about t hat for now, is
2 cycles and I have arrowed in t he second cycle, no difference which cycle I arrow as t hey are
bot h repeat s. Anyway I had t o arrow t he second cycle so as not t o int rude on t he am plit ude
line in t he first cycle.
The height or peak of t he waveform is t he am plit ude and t he lengt h is m easured as 2 cycles
and t his is done very sim ply.
I m agine a sound and how it st art s. I t st art s from 0 t hen goes up, hangs about and t hen drops
off.
I n t he diagram you can see t he waveform st art s at zero, goes up, drops t o zero t hen goes t o
t he negat ive area and t hen clim bs t o zero again. This is using t he wave t heory we defined
earlier and all w aveform s are represent ed like t his, as a graph, and how each cycle behaves or
how a num ber of cycles behave in relat ion t o each ot her.
For now you do not need t o worry about com plex waveform s and any ot her fact ors regarding
waveform s as we will deal wit h t hem as we go along, at your pace, t hat way you do not feel as
if t here is t oo m uch inform at ion t o learn.
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This is m eant t o be fun so let ’s keep it t hat way
The final m ost im port ant com ponent of sound is TI M BRE.
iii. TI M BRE
This is what defines t he t onal qualit y of a sound.
A C4 not e played on a piano and at t he sam e level as a C4 not e played on a saxophone does
not produce t he sam e sound or t im bre. They are bot h t he sam e level and bot h played at C4
but bot h have dist inct ly different sounds or t im bres.
Tim bres are m ade up of waveform s and it is t hese waveform s t hat go t o m ake up t he t onal
qualit y of a sound. This is called t im bre.
This is t he m ain reason why one sound at a cert ain frequency will sound com plet ely different
t o anot her sound at t he sam e frequency.
When you com e t o use EQ you will underst and why we do not have one overall frequency
chart for all sounds.
A fem ale voice at C3 will sound com plet ely different t o a m ale voice at C3 so t he EQ propert ies
will have t o be different as t he t im bres of t he t wo sounds are dist inct ly different .
The first challenge when EQing m usical sounds is in deciding which area of t he frequency
spect rum cor responds t o which elem ent of a sound's t im bre. I f you want t o em phasize t he
at t ack of a bass drum , where should you boost ? Alt ernat ively, if your vocals sound boxy,
where can you cut or boost m ost effect ively?
This area is called t he ba n dw idt h , t he area at which you want t o boost or cut .
I t is also im port ant t o not e t hat we hum ans have a hearing range of bet ween 20 Hz t o 20 kHz.
To be honest , anyt hing at t he 20 Hz level is felt m ore t han heard. This is why producer s
cleverly add lower frequencies t o a t rack for t hat big club feel.
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5 . Fu n da m e n t a ls a n d H a r m on ics
One t hing t hat can help a lit t le in deciding t his is t o know what frequencies correspond t o t he
fu n da m e n t a ls of each m usical pit ch. For a st art , t his allows you t o define t he lower lim it of
t he range of frequencies generat ed by pit ched sounds.
Let ’s t alk a lit t le about H a r m on ics.
First , t he em ot ional definit ion or descript ion:
All m usical t ones have a com plex waveform , m ade up from loads of different frequencies.
All sounds ar e form ed using a com binat ion of sine waves at varying frequencies and
am plit udes.
Now it get s a t ouch m ore involved. I f we look at t he frequencies of a com plex waveform , t hen
t he lowest frequency is called t he fu n da m e n t a l fr e qu e n cy .
The fundam ent al frequency det erm ines t he pit ch of t he sound. The higher frequencies are
called ove r t on e s. I f t he overt ones ar e m ult iples of ( x1, x2, x3 et c) t he fundam ent al
frequency t hen t hey are called h a r m on ics. The overt ones or u ppe r pa r t ia ls as som e people
like t o refer t o t hem as, m ust be m ult iples of t he fundam ent al t o be known as harm onics.
These frequencies and t heir am plit udes det erm ine t he t im bre of a sound.
Now, t he sim pler explanat ion:
I f you have a waveform t hat has a fundam ent al frequency of 100 kHz, t hen t he second
harm onic will be 200 kHz and t he t hird harm onic will be 300 kHz and so on……
I f you t hink about t he irregular waveform of noise t hen you will underst and t hat it has no
harm onics. Noise cont ains a wide band of frequencies and it is generally accept ed t hat , at
waveform level, t here are no harm onics as t he waveform is non- repeat ing.
I have found t hat by boost ing sounds below t heir fundam ent al frequency, noise of som e sort is
always int roduced int o t he m ix. I n fact , it is always a good policy t o use a high pass filt er
along wit h t he use of EQ on a sound. I will com e t o t his lat er when dealing wit h m et hods and
t echniques of using EQ.
The concept of harm onics, fundam ent als, overt ones et c seem s daunt ing, but it ’s not . The
above is sim ply t o give you a bet t er and m ore t horough insight int o what sound and all of it ’s
com ponent s are.
I do not expect you t o know all of t he above but if you want t o be m ore proficient at your
vocat ion, t hen it helps t o t ry t o underst and what we have covered here.
However, as we have covered correct ive EQ, albeit briefly, it is also vit al t o underst and t hat
EQ is not only about boost ing and cut t ing frequencies, but also about pe r ce pt ion .
Below is a list wit h approxim at e figures for inst rum ent frequency ranges and t heir
fundam ent als. As I said earlier, I do not like list s t hat purport t o be an accurat e frequency
range t able for varying inst rum ent s, due t o t heir inaccuracy. However, t his list is sim ply t o
help you underst and t he fundam ent al and harm onic frequencies of a select ion of inst rum ent s.
I am only list ing t he t ypes of sounds t hat I feel will be used in m ost m odern recordings for
popular m usic, so have om it t ed t he orchest ral and acoust ic inst rum ent s.
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I n st r u m e n t
Kick Drum
Snare Drum
Cym bal
Acoust ic Bass
Elect ric Bass
Acoust ic Guit ar
Elect ric Guit ar
Piano
Bass Voice
Alt o Voice
Soprano Voice
Fu n da m e n t a ls
30- 145 Hz
100- 200 Hz
300- 580 Hz
40- 295 Hz
40- 300 Hz
82- 988 Hz
82- 1319 Hz
28- 4196 Hz
87- 392 Hz
175- 698 Hz
247- 1175 Hz
H a r m on ic
1- 6 kHz
1- 20 kHz
1- 15 kHz
1- 5 kHz
1- 7 kHz
1- 15 kHz
1- 15 kHz
5- 8 kHz
1- 12 kHz
2- 12 kHz
2- 12 kHz
The above ar e only guides, and t o be used purely as a reference.
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6 . To Cu t or t o Boost
Anot her com m on problem t hat beginners m ake is t o boost frequencies in a m ix t o t ry t o m ake
it st and out m ore. This is t rue part icularly for drum sounds. The problem here is t hat noise is
also boost ed so what you end up wit h is a noisy sound in t he m ix, which st ands out even m ore
t han int ended. So t he beginner t ries t o com pensat e by boost ing ot her sounds t o at t ain an
even balance. Yep, you guessed it , m ore noise.
The t rue art of EQ is t o cut , not boost .
However, boost ing cert ain frequencies by sm all am ount s can have a dist inct im pact on a m ix.
The t rick is t o know when t o cut and when t o boost .
To be able t o inst inct ively know when t o cut ( roll- off) or boost , you need t o underst and
frequencies. Basses and pads sound gr eat and full on t heir own, but com bine t hem in a m ix
and t hey st art t o sound m uddy. This is because t hey share so m any of t he lower frequencies.
By cut t ing a cert ain range of frequencies from eit her or bot h, you will, in effect , give t he
percept ion of boost ing t he lower end, or upper end if you are cut t ing t he lower frequencies. I t
always helps t o cut cert ain frequencies wit h t he aim of accent uat ing ot her frequencies. This is
t he Art .
Why?
Because t he individual sounds sound clear and balanced, inst ead of m uddy and biased. By
t aking away, we give. By boost ing t oo m any frequencies and channels, we com prom ise t he
headroom of t he dynam ic range of t he audio. Whet her it is in a m ixer or DAW syst em , boost
t oo m uch and you ent er clipping and dist ort ion t errit ory.
The one area t hat is always t he hardest t o learn is t he m id- end. So m any sounds share t his
frequency spect rum t hat it can lead t o confusion when it com es t o finding a good balance of
frequencies in a m ix.
This is why cut t ing or boost ing sm all am ount s around dist inct fr equency spect rum s of
individual sounds can be so m uch m ore effect ive t han choosing an overall frequency range for
a num ber of sounds and alt ering t hat .
The sam e is t rue of t he whole m ix it self. EQ can be used t o alt er t he apparent loudness of a
m ix, a t echnique com m only used by m ast ering houses.
Our hearing syst em 's frequency response changes w it h loudness. I t is im port ant t o m onit or at
a realist ic and sensible volum e when applying EQ, because t he perceived effect m ay be quit e
different at higher or lower list ening levels.
However, t he fact t hat t he ear get s m ore sensit ive t o high and low frequencies t he higher t he
int ensit y of t he sound, m eans t hat t he brain t ends t o int erpret any sound which is
com parat ively rich in t hese frequencies as loud.
Therefore, if you want m usic t o sound louder at low list ening levels, t hen it m akes sense t o
boost at t he ext rem es of t he frequency range. This is what som e hi- fi syst em s do when t he
Boost or Loudness but t on is used.
I n m ost playback syst em s, you will see what is referred t o as t he ‘sm ile’ curve on graphic EQs.
The sm ile shape denot es t hat t here is a dip in t he m id frequencies and sm all boost s in t he
ext rem e frequencies. Always be aware as t o t he difference bet ween act ual and perceived.
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I t is also t rue t o st at e t hat at low list ening levels, t he hum an hearing syst em encount ers
difficult ies hearing very low and very high frequencies.
This is called t he Flet cher Munson Effect .
I n t his inst ance, EQ is used t o cut and boost select ed frequencies, so t hat a m ore balanced
gain st ruct ure is kept right t hroughout t he hearing spect rum at low list ening levels.
Masking is anot her problem t hat can be t reat ed wit h sensible use of EQ.
How m any t im es have you used a sound, t hat on it ’s own sounds excellent , but placed
alongside anot her sound, get s swallowed up by t he second sound?
This happens because t he t wo sounds have very sim ilar frequencies, so one ‘m asks’, or hides,
t he ot her sound. This result s in t he m asked sound sounding dull, or j ust sim ply unheard. EQ is
a very good t ool t o use in t hese inst ances. By cut t ing away cert ain frequencies from one of t he
sounds, you will invariably expose and boost t he frequencies of t he ot her sound, t hus
accom plishing separat ion and dist inct ion bet ween t he t wo sounds.
Anot her pit fall t hat m ost beginners and som e pros fall int o is what I call t he EQ Syndrom e.
This happens when a m ix is poorly recorded wit h lit t le separat ion in t he sounds and EQ is used
t o t ry t o ‘separat e’ and ‘cleanse’ t he sounds. This always result s in a brit t le m ix wit h individual
sound com ponent s sounding as if t hey do not belong t oget her. Anot her exam ple of t his EQ
Syndrom e is when an engineer or producer feels t hat t hey have t o EQ every channel t o gain a
st am p on t heir ‘feel’. This com plaint is quit e com m on in cert ain Hip Hop and Rap songs
whereby t he drive ( drum beat and bass line) of t he song sounds separat e from t he vocals.
This can act ually be a good t hing, if t he effect is int ended, but t he ear begins t o at t une it self t o
t he separat e frequency bands inst ead of a rich t apest ry of frequencies, and t he song t hen
st art s t o ‘t ire’ t he list ener.
I n t hese inst ances it is cr ucial t o have a clean and balanced recor ding, so t hat t he EQ process
can be creat ive as opposed t o correct iv e. You should st rive t o record t he source sound
elem ent s at near enough t he frequencies t hat you will event ually release. That way you will
only need t o m ake m inor adj ust m ent s inst ead of sweeping corr ect ions.
The added advant age of a clean and balanced recording, wit h em phasis on t he correct source
frequencies, is t hat you can always com e back and rem ix t he ent ire recording off a blank
palet t e. The recording will never t ire it self and never be const rict ed in t erm s of frequencies.
This will always allow for refreshing rem ixes.
EQ has m any guises.
We use correct ive EQ in edit ing suit es and product ion houses t o isolat e and dim inish a
frequency or sound, t o accent uat e or elevate a part icular sound, frequency or recording.
Classic cases are t hat of broadcast engineers having t o isolat e t he narrat ive or spoken part
am idst a plet hora of ot her background noises, or t o sim ply rem ove a click or unwant ed sound,
and, even m ore com m only, t o alt er t he spoken par t t o sound m ore pleasing in t he event t hat
it is harsh sounding. The lat t er is m ore in t he dom ain of creat ive or m usical EQ.
Using EQ as a t ool t o separat e t racks is anot her favourit e of producers.
This is act ually quit e an im port ant procedure, but one t hat does need a careful approach.
I t is im perat ive t hat your recordings ar e as clean as possible and have a perfect S/ N rat io. This
will ensure t hat sm all am ount s of EQ boost , on select ive frequencies, will at t ain t he best
result s.
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A lot of beginners m ake t he m ist ake of poorly recording t he source m at erial and t hen using EQ
t o t ry t o separat e and boost t he gains of t he recorded t racks.
Separat ion can only be t rut hfully affect ed if t here is a clear dist inct ion bet ween frequencies, so
t hat you only need t o isolat e sm all frequency ranges and apply nom inal boost s. Having a
m uddy m ix of low end inst rum ent s m akes for having t o perform som e ext rem e cut s/ boost s,
and t his will be m ore dest ruct ive t han creat ive.
Dist ance has a dram at ic effect on sound.
High frequency sounds are da m pe n e d and absorbed by t he frict ion of air, so t hey sound
quiet er or furt her away.
The furt her t he sound t ravels, t he m ore it is dam pened.
We can m im ic t his in a m ix by cut t ing backing vocals at , for exam ple, t he 10 kHz range, t hus
m aking it sit back in t he m ix and in t urn bringing out t he lead vocals t o t he front of t he m ix.
Percept ion gained by clever use of EQ.
I t t hen follows t hat if you dam pen a sound, you will invariable give it t he percept ion of being
furt her away or quiet er.
Use t his piece of inform at ion.
I f you need t o bring a sound down in a m ix, som et im es all it needs is t o have t he t op
frequencies rolled off.
The sam e t hinking can be applied when you want t o bring a sound out in a m ix. I nst ead of
boost ing t he gain of t he whole sound, it can be very effect ive t o boost som e of t he higher
frequencies. But , rem em ber t hat we are t alking about very sm all changes her e, not huge knob
t urns.
Anot her area of separat ion t hat is very im port ant is t hat of redundant frequencies. This is m y
very flash way of saying ‘frequencies t hat are not needed’.
You will find t hat t here ar e a lot of inst rum ent s t hat share low frequencies, not j ust basses and
kick drum s. So, rem oving predefined low frequency ranges from som e of t he low end
inst rum ent s in your m ix can act ually separat e and define t he low frequencies even m ore.
Recording your t racks rich in frequencies allows you t he scope t o cut or boost any frequency
range, as it already exist s in t he recorded audio. I cannot t his enough.
Separat ing t he frequencies of inst rum ent s by t he use of EQ is a t radit ional, yet subt le, m et hod
of creat ive and correct ive EQ.
Creat ive EQ is an art form in it self.
Exam ples of t his would ent ail, bringing out t he best in a lead vocal line and yet keeping it
balanced wit h t he backing vocals, or t o m ix t he drive elem ent of a t rack t o it ’s opt im um club
feel, or sim ply t o use coloured EQs t o add t o or alt er an exist ing sound. The list is endless. You
are only lim it ed by your knowledge on t he subj ect , and, of course, having an ear helps, but
t his is not a pre requisit e.
Finally, we use EQ at t he m ast ering st age t o best represent t he final st ereo m ix for it ’s genre
and m edium . Once all t he elem ent s are in place and a m ix of t he session is handed t o t he
m ast ering house, t he real t reat m ent t akes place t o bring out t he best in t he final m ix and t o
m ake sure t hat t here is a good dynam ic range and all t he elem ent s are in place for what ever
t he m arket t he m ix is aim ed at .
We have also arrived int o t he preset based EQ world for m ost hi- fi owners.
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I n fact , t his has got t o t he point whereby hi- fi m anufact urers put preset EQ set t ings on t heir
syst em s for t he list ener t o choose from . Ghast ly preset s called Pop, Am bient , Disco et c. are
predefined EQ t em plat es t hat you can t weak t o your heart ’s cont ent .
A well m ast ered m ix will not need any addit ional EQ m anipulat ing at t he list ening st age, as
good m ast ering houses will t reat t he signal for opt im um use on all list ening m edium s.
A good m ast ering house/ engineer can m ake or break your t rack in t he com m ercial vein. Their
m ost valued weapon: EQ.
So, we now underst and how im port ant EQ is and t he fundam ent al uses it m ight have, but we
have not delved int o t he different t ype of EQ available.
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7 . Te r m in ology a n d de fin it ion s- Filt e r s
To furt her underst and t he t erm inology used in t his E- book, I feel it is essent ial t hat you
underst and t he following:
Cu t - off fr e qu e n cy
This is t he point ( frequency) at which t he filt er begins t o filt er ( block or cut out ) . The filt er will
lower t he volum e of t he frequencies above or below t he cut - off frequency depending on t he
t ype of filt er used.
At t e n u a t ion
This ‘lowering of t he volum e of t he frequencies,’ is called At t e n u a t ion . I n t he case of a low
pass filt er, t he frequencies above t he cut off are at t enuat ed. I n t he case of a high pass filt er,
t he frequencies below t he cut off are at t enuat ed.
Re son a n ce
Boost ing t he narrow band of frequencies at t he cut - off point is called resonance. Also know as
Q and bandw idt h, in effect , he higher t he resonance, t he narrower t he bandwidt h.
A very cool way of underst anding what resonance sounds like is t o perform what we call a
‘sw e e p’. Yes, anot her flash and funky t erm we progr am m ers use t o explain som et hing really
sim ple.
Sweeping t he filt er m eans m anually t urning t he resonance knob, clockwise and ant i- clockwise.
Select a waveform , set t he cut - off point and t urn t he resonance knob and list en
t o t he result s. As you are sweeping, t he resonance goes t hrough all t he different frequency
harm onics, of t he waveform , and boost s/ cut s t hem , at t he cut - off point .
Q
Also known as ‘w idt h of t h e filt e r r e spon se ’, t his is t he ‘ce n t r e fr e qu e n cy ’ of t he
bandwidt h and is m easured in Hz. Also know as bandwidt h and resonance.
A high Q value denot es a narrow filt er widt h ( bandwidt h) . A low Q value denot es a wide filt er
widt h ( bandwidt h) .
This is act ually a very im port ant piece of inform at ion because wit h t he Q cont rol alone, you
can m ake your audio sound high and brit t le or warm and m usical. This does not m ean t hat
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you m ust use low Q values all t he t im e, in t he hope of at t aining warm t h, but you m ust
underst and what frequencies need filt ering. I f your int ent is t o use EQ as a m usical t ool, t hen
be aware of what t he Q value can do t o audio. For creat ive EQ, t his is a weapon oft en ignored.
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8 . Type s of EQ
To begin t o underst and t he EQ, we need t o first define t he t wo cat egories it falls in, Pa ssive
a nd Act ive .
Pa ssive EQs
These t ypes of EQs have t he dist inct ion of being ext rem ely sim ple in design and, m ore
im port ant ly, t hey cannot boost frequencies, only cut . The way t hey work is act ually very m uch
t o do wit h percept ion.
By cut t ing, for exam ple, low frequencies ( bass) , t hey m ake t he m id and high frequencies
sound ‘louder’.
Passive EQs do have t heir uses. Alt hough t hey are inflexible, t hey can perform reduct ion t asks
reasonably well. By cut t ing high frequencies, t hey are able t o cut or lower hiss ( high frequency
noise) . However, by t heir very nat ure, passive EQs, or filt ers, have t o t hen have t he signal
boost ed t o com pensat e for t he cut . This, in it self, int roduces noise int o t he signal pat h. The
noise com ing from t he am p used t o boost t he signal.
Act ive EQs
Because of t he lim it at ions of passive EQs, m ost EQs are built around act ive filt er circuit s which
use frequency select ive com ponent s, t oget her wit h a low noise am plifier.
And it is t his t ype of EQ t hat we are now going t o concent rat e on.
Fix e d Fr e que n cy EQ
Pret t y self explanat ory, t his EQ allows cut / boost of one or m ore frequencies. There are no
addit ional cont rols over t he usual com ponent s, like bandwidt h, Q, et c.
Pe a k in g EQ
A peaking EQ is an EQ which boost s a specific band of frequencies.
Whereas a shelving filt er has a shelf like curve, t his filt er has a bell shaped curve. The Q
set t ing det er m ines t he widt h of t he bell, while boost or cut det er m ines t he height or dept h of
t he bell.
Tw o Ba n d or Th r e e Ba n d
These t ypes of EQ sim ply have t wo or t hree separat e frequency ranges. Usually denot ed as
low, m id and high, t hese bands can only be cut or boost ed.
Sh e lvin g Filt e r / EQ
We have t ouched on t he use of t one cont rols t hat are form s of EQ. These cont rols cont rol a
t ype of filt er t hat is called a sh e lvin g filt er. I n t he case of t he bass and t reble knobs, low pass
and high pass shelving filt ers are used respect ively.
A low- pass shelving filt er passes all frequencies below it s cut - off frequency, but a t t e n u a t e s
all frequencies above it s cut - off frequency. Sim ilarly, a high- pass filt er passes all frequencies
above it s cut - off frequency, but affect s all frequencies below it s cut - off frequency.
This is t he sim plest t ype of act ive EQ. This EQ can shape response in a num ber of ways:
boost / cut low frequencies, boost / cut high frequencies. This is why I have included t he graph t o
dem onst rat e what happens wit h t he filt ers, low and high pass, in t his t ype of EQ.
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Most m ixers will allow for low and high frequency EQ, and in t he case of shelving filt ers, t heir
m id frequencies are usually fixed.
I t is also com m on for t he filt er slope t o be 6 dB per oct ave. This allows for a gent ler effect .
The shape is shelf like, so t he boost or cut is progressive over a range. Filt ers do not have a
no- effect at a frequency and t hen inst ant ly j um p and suddenly reappear at t he next
frequency. They have t o get t here som ehow. The way, and by how m uch, t hey get t here is
called t he gr a die n t or slope . I n t he case of t he shelving filt er, t he m ost com m on slope is 6
dB gain change per oct av e ( doubling of t he frequency) . I t t akes t im e for t he filt er t o at t enuat e
frequencies, in proport ion t o t he dist ance from t he cut - off point . This is t he slope .
The diagram below illust rat es what happens if you cut or boost frequencies in a low- pass and
a hi- pass filt er.
Low Pa ss
H igh Pa ss
Blue = Boost
Red = Cut
Gr a ph ic EQ
A graphic equalizer is sim ply a set of filt ers, each wit h a fixed cent re frequency t hat cannot be
changed.
The only cont rol you have is t he am ount of boost cut or in each frequency band. This boost or
cut is m ost oft en cont rolled wit h sliders. The sliders are a graphic represent at ion of t he
frequency response, hence t he nam e 'graphic' equalizer.
The m ore frequency bands you have, t he m ore cont rol and accuracy you have over t he
frequency response.
Mixing consoles rarely have graphic EQs, but PA m ixers oft en have a st ereo gr aphic EQ for
EQing t he final st ereo out put .
A graphic equalizer uses a set of ba n d- pa ss filt ers t hat are designed t o com plet ely isolat e
cert ain frequency bands.
The diagram below shows t he frequency response of a band- pass filt er.
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Ba n d Pa ss Filt e r
A filt er t hat passes frequencies bet ween t wo lim it s is known as a ba n d- pa ss filt e r .
This is a great filt er. I t at t enuat es frequencies below and above t he cut - off and leaves t he
frequencies at t he cut - off. I t is, in effect , a low pass and a high pass t oget her. The cool t hing
about t his filt er is t hat you can elim inat e t he lower and higher frequencies and be left wit h a
band of frequencies t hat you can t hen use as eit her an effect , as in having t hat real m id range
t ype of old radio sound, or use it for isolat ing a narrow band of frequencies in recordings t hat
have t oo m uch low and high end.
Try t his filt er on synt hesizer sounds and you will com e up wit h som e wacky sounds. I t really is
a useful filt er and if you can run m ore t han one at a t im e, and select different cut - offs for each
one, t hen you will get even m ore int erest ing result s. I nt erest ingly enough, band pass filt ering
is used on form ant filt ers t hat you find on so m any soft synt hs, plugins, synt hesizers and
sam plers. Em u are known for som e of t heir form at filt ers and t he t echnology is based around
band pass filt ers.
I t is also good for t hinning out sounds and can be used on percussive sounds as well as
creat ing effect s t ype of sounds.
I oft en get em ails from program m ers want ing t o know how t hey can get t hat old radio effect
or t elephone line chat effect or even NASA space dialogue from space t o Houst on. Well, t his is
one of t he t ools. Use it and experim ent .
You will enj oy t his one.
N ot ch Filt e r – a lso k n ow a s Ba n d Re j e ct Filt e r
The inverse of a band pass is t he not ch filt er.
This is a very pot ent EQ/ filt er. I t can hom e in on a single frequency band, and cut / boost it .
Used specifically for ‘problem ’ frequencies, t he not ch can be one of t he m ost useful filt ers.
This is t he exact opposit e of t he band pass filt er. I t allows frequencies below and above t he
cut - off and at t enuat es t he frequencies around t he cut - off point .
Why is t his good?
Well, it elim inat es a narrow band of frequencies, t he frequencies around t he cut - off, so, t hat in
it self is a great t ool. You can use t his on all sounds and can have a dist inct effect on a sound,
not only in t erm s of elim inat ing t he frequencies t hat you want elim inat ed, but also in t erm s of
creat ing a new flavour t o a sound.
But it s real pot ency is in elim inat ing frequencies you don’t want . Because you select t he cut off point , in essence, you are select ing t he frequencies around t hat cut - off point and
elim inat ing t hem .
An invaluable t ool when you want t o hone in on a band of frequencies locat ed, for exam ple,
right in t he m iddle of a sound or recording. I som et im es use a not ch filt er on drum sounds
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t hat have a m uddy or heavy m id sect ion, or on sounds t hat have a lit t le noise or frequency
clash in t he m id sect ion of a sound.
Pa r a m e t r ic
This filt er cont rols t hree param et ers, frequency, bandwidt h and gain. You select t he range of
frequencies you want t o boost or cut , you select t he widt h of t hat range and use t he gain t o
boost or cut t he frequencies, wit hin t he select ed bandwidt h, by a select ed am ount .
The frequencies not in t he bandwidt h are not alt ered. I f you widen t he bandwidt h t o t he lim it
of t he upper and lower frequencies ranges t hen t his is called shelving. Most param et ric filt ers
have shelving param et ers.
Param et ric filt ers are great for m ore com plex filt ering j obs and can be used t o creat e real
dynam ic effect s because t hey can at t enuat e or boost any range of frequencies.
Basically, t he param et ric EQ places several act ive filt ers across t he frequency spect rum . Each
filt er is designat ed t o a frequency range, low, m id, high et c. You have t he usual cut / boost ,
resonant frequency and bandwidt h. I t is t hese qualit ies and t he cont rol over t hem t hat places
t his part icular EQ in t he producer’s arsenal of dynam ic t ools, and m akes it det ailed and
versat ile.
However, you need t o underst and what you are doing when using a param et r ic EQ, ot herwise
t hings can go very wrong.
Underst and frequencies and sound, and you will be in t ot al cont rol.
Qu a si- pa r a m e t r ic EQ
This is j ust anot her form of param et ric EQ but wit hout t he bandwidt h cont rol.
Sw e e p EQ
This is very sim ilar t o a band pass filt er, but wit h variable cent re frequency, and no cont rol
over t he widt h of t he filt er response ( Q) .
You will find t hat m ost m ixers will have band pass EQ, and som e will have sweep EQ ( where
t he cent re frequency can be varied, also known as ‘t u n e a ble ’) , but very few, m ainly digit al,
will have param et ric EQ.
Pa r a gr a ph ic EQ
Anot her variat ion on t he graphic EQ. This EQ provides cont rol over t he cent re frequency of
each band.
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9 . Ph a se t h e bi- pr odu ct
A very im port ant aspect of EQ, in relat ion t o affect ed and non- affect ed frequencies, is t hat of
phase.
We know t hat affect ing t he frequencies t hat we have chosen for equalisat ion, also affect s t he
phase of t hose select ed frequencies, in relat ion t o t he unaffect ed frequencies. The process
it self also affect s t he frequency response of t he signal being t reat ed. We are t alking about t iny
offset s here. Every t im e a frequency range is select ed and t reat ed, t he affect ed frequencies
will exhibit displacem ent , in relat ion t o t he unaffect ed frequencies. This offset is phase.
Whereas we are not t alking about big swirling phase effect s, as in guit ar phasing, we are,
however, t alking about t he pure definit ion of phase. This is probably not som et hing t hat you
will hear as phase, but it is som et hing t hat affect s our percept ion of t he t reat ed frequencies.
Depending on t he nat ure of t he displacem ent , we perceive t he t r eat ed frequencies as dist ance.
Why is t his im port ant ?
This is what different iat es t he t onal charact erist ics of analogue hardware and digit al soft ware
EQs.
The analogue EQ unit will exhibit far m ore m usical phase changes t han it ’s digit al count erpart ,
and at very low gains, whereas t he digit al EQ unit will have t he advant age of leaving t he
phase relat ionships hardly affect ed, t hus allowing for m ore robust gain changes.
They bot h have t heir uses.
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1 0 . Le t I t Be gin
We have covered EQ as a subj ect . I t is now t im e t o begin wit h walk t hrough exam ples.
The following exam ples will deal wit h inst rum ent s and vocals. This way, we have a good
variet y of scenarios t o deal wit h, and a good range of frequencies t o cover and m anipulat e.
Drum s – Kick
Fig 1
List en t o t his file ( K0 2 0 )
As you can see from t he above im age ( Fig 1 ) , I have opened up a kick file in Sound Forge. We
are now going t o m anipulat e t his file and creat e new files, by t he sim ple use of EQ.
However, before we perfor m any t ype of m anipulat ion, I want t o show you how t o evaluat e
and see t he frequency spect rum ( range) of any select ed audio file.
For t his, we use a piece of soft ware, or hardware, called a spect r um analyser.
Sound Forge has t his t ool under t he m enu opt ion, Tools - Spect rum Analyser.
The im age below ( Fig 2 ) , clearly displays t he frequency spect rum of t he kick when played.
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Fig 2
By using t he analyser we are able t o fully see t he frequency st ar t , t he frequency body and t he
frequency t ail- off.
This t ype of t ool is invaluable in helping us t o apply EQ.
You will appreciat e how useful t his t ool is when we com e t o rem oving unwant ed frequencies,
or when we com e t o using EQ t o eit her correct flawed vocals, or t hin out or t hicken vocal lines.
The Y axis ( left hand side figures) denot es am plit ude/ level in dB.
The X axis ( bot t om figures) denot es t he frequency in Hz.
The analyser t ells us t hat t his kick st art s on a frequency of 20 Hz at – 45 dB ( at t ack) , rises t o
65 Hz at - 36 dB ( height of at t ack’s decay) , drops t o and levels off at around 88 dB.
This helps us a great deal in underst anding t he charact erist ic and shape of t he kick file and
t his in t urn gives us a det ailed num erical and graphical reference for set t ing up our EQ
param et ers.
What did I j ust say, in English?
Sim ple: check t he sam e im age but zoom ed in ( Fig 3 )
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Fig 3
I highlight ed t he peak of t he kick file’s waveform wit h t he m ouse and it gave m e t he figure
above.
I can m ove m y m ouse over any part of t he waveform and it will highlight t he dat a I need.
Wit h t his exam ple, I can now decide what t ype of EQ I want t o apply and by how m uch.
The punch com ponent , or at t ack, of m ost bass drum s lies bet ween about 60 and 110Hz. This
is where you find t he low- end ener gy of m ost kicks. Below t his range, you'll m ost ly feel, rat her
t han hear, any boost , and it 's easy t o eit her neglect t his and be left wit h all sort s of frequency
im balances in you