| Definitions/Explanations: |
| Equalization is the increase or decrease of
signal strength for a portion of (a band of) audio frequencies. The audio we record
(the sound made by instruments or voices) is complex. By this we mean that
it is composed of energy at different audio frequencies. If we take a bass control
(a simple equalizer) and turn the knob clockwise, we will get an increase in strength of
the signal (or the signal component) that has lower frequencies (usually any component
below about 500 Hz). Thus equalization effects the tone because it changes the level
relationship of the fundamental
and harmonic frequencies. |
| A Shelf Equalizer boosts (or reduces) energy
at the set frequency and all audio frequencies above it (a high-frequency self
control) or all audio frequencies below it (a low-frequency shelf control). |
| A Peak Equalizer boosts (or reduces) at the
set frequency and a band of frequencies close to the set frequency. |
| The "Q" control sets the width of
the band of frequencies that will be boosted or reduced; in other words it affects the
amount of frequencies around the center frequency which will have a similar amount of
boost or reduction. The width of the band is given in octaves. Q affects this width,
but high Q numbers mean a narrower band of frequencies will be affected. To start,
you will need to be able to identify the "Q" settings that go as narrow as 1/2
octave to as wide as 2 octaves. The conversion chart below relates Q settings to
bandwidth. |
Q Setting |
Bandwidth |
0.7 |
2 Octaves |
1.0 |
1 1/3
Octaves |
1.4 |
1 Octave |
2.8,
no 2.9* |
1/2 Octave |
|
*See
"We Stand
Corrected" Article |
|
| The amount of boost or cut is determined by
the "dB" setting of the equalizer. Most equalizers can boost or reduce
energy by 12 dB (up to 4 times/one-quarter the level). Some equalizers can boost or
reduce up to 15 dB. |
| Tips/Guidelines on determining
Shelf/Peak/Q & Amount of EQ: |
1 |
Shelf equalizers are good for general tone
changes in the bottom or top three octaves of the audio frequencies. Thus a
low-frequency shelf control could be used effectively at 320 Hz or below and a high
frequency shelf control at 2500 Hz or higher. |
2 |
| Shelf equalizers are best used for reducing
rather than boosting energy. The very top octave (10 kHz - 20 kHz) often has more
noise component (hiss) than useful sound. The same is true for the lowest octave (20
Hz to 40 Hz) except the noise is rumble rather than hiss. When boosting for general
increase in brightness or general increase in bass, use a peak equalizer. |
| Suggested settings: For general
increase in brightness, boost 5 kHz with a 2 octave bandwidth (Q= 0.7). For general
increase in bass, boost 80 Hz with a two octave bandwidth (Q=0.7). |
|
3 |
The Q setting of 1.0 (1 1/3 octaves), I call the
"Magic Q". In general this is a bandwidth that matches how the different
instruments cover the different frequency ranges of audio. For more percussive
instruments (such as drums), you can narrow the bandwidth with Q settings as high as about
2.8. For more melodic instruments, such as voices and stringed instruments, you can
broaden the bandwidth down with Q settings as low as 0.7. |
4 |
In general, boost less and cut more. The
ear is accustomed to hearing reduction in energy in a band (due to sound-absorbing
material for instance), thus the ear will hear a boost easier than a cut (a
reduction). In general, a 6 dB boost is about as apparent as a 9 dB reduction.
When equalizing during mixing try to reduce unwanted frequencies more than you boost
desired frequencies. This will result in "clarity" with less
"falseness" to the sound. If you look at a console after a mix that has
been done by an experienced engineer, you will find more reduction settings than boosting
settings. |
5 |
| Equalization is all to often misused to
compensate for poor level settings. If you find you want your settings to be more
than 6 dB boost, investigate and see if a readjustment of levels could help, reducing the
amount of boost at the equalizer. |
| Training hint: I recommend to someone new to
use the "6 dB rule" - Never, while recording or mixing, boost more than 6
dB with the equalizer, period for the first 50 mixes you do. |
|
|
| Recommended Frequencies - Expanded |
Use the following Recommended Expanded Frequencies Chart as a starting
point.
FREQUENCY: |
USES: |
50Hz |
| 1. Increase to add more fullness to
lowest frequency instruments like foot, toms, and the bass. Peak equalization with a 1.4 Q. |
| 2. Reduce to decrease the
"boom" of the bass and will increase overtones and the recognition of bass line
in the mix. This is most often used on loud bass lines like rock. Shelf equalization. |
|
100Hz |
| 1. Increase to add a harder bass
sound to lowest frequency instruments. Peak Equalization with a Q of 1.0 to 1.4.. |
| 2. Increase to add fullness to
guitars, snare. Peak
Equalization with a Q of 1.0.. |
| 3. Increase to add warmth to piano
and horns. Peak Equalization.
For piano use a Q of 1.0. With horn use a Q of 1.4.. |
| 4. Reduce to remove boom on guitars
& increase clarity. Peak
Equalization with a Q of 1.0 to 1.4.. |
|
200Hz |
| 1. Increase to add fullness to
vocals. Peak Equalization with a
Q of 0.7 to 1.0.. |
| 2. Increase to add fullness to
snare and guitar ( harder sound ). Peak Equalization with a Q of 1.4. |
| 3. Reduce to decrease muddiness of
vocals or mid-range instruments. Peak Equalization with a Q of 1.0. |
| 4. Reduce to decrease gong sound of
cymbals. Peak Equalization
with a Q of 1.0. |
|
400Hz |
| 1. Increase to add clarity to bass
lines especially when speakers are at low volume. Peak Equalization with a Q of 1.0. |
| 2. Reduce to decrease
"cardboard" sound of lower drums (foot and toms). Peak Equalization with a Q of 1.4. |
| 3. Reduce to decrease ambiance on
cymbals. Peak Equalization with
a Q of 0.7 to 1.0. Alternately try a shelf EQ with a 320 Hz frequency setting. |
|
800Hz |
| 1. Increase for clarity and
"punch" of bass. Peak
Equalization with a Q of 1.4. |
| 2. Reduce to remove
"cheap" sound of guitars. Peak Equalization with a Q of 1.0. |
|
1.5KHz |
| 1. Increase for "clarity"
and "pluck" of bass.
Peak Equalization with a Q of 1.4.. |
| 2. Reduce to remove dullness of
guitars. Peak Equalization with
a Q of 1.0. |
|
3KHz |
| 1. Increase for more
"pluck" of bass. Peak
Equalization with a Q of 1.4. |
| 2. Increase for more attack of
electric / acoustic guitar. Peak Equalization with a Q of 1.4. |
| 3. Increase for more attack on low
piano parts. Peak
Equalization with a Q of 1.0. |
| 4. Increase for more clarity /
hardness on voice. Peak
Equalization with a Q of 1.0. |
| 5. Reduce to increase breathy, soft
sound on background vocals. Peak Equalization with a Q of 1.0. |
| 6. Reduce to disguise out-of-tune
vocals / guitars. Peak
Equalization with a Q of 1.0. |
| 7. Increase for more attack on the
snare or other drums. Peak
Equalization with a Q of 1.4 to 2.8. |
|
5KHz |
| 1. Increase for vocal presence. Peak Equalization with a Q of 1.0. |
| 2. Increase low frequency drum
attack ( foot / toms). Peak
Equalization with a Q of 1.4 to 2.8. |
| 3. Increase for more "finger
sound" on bass. Peak
Equalization with a Q of 1.4. |
| 4. Increase attack of piano,
acoustic guitar and brightness on guitars (especially rock guitars). Peak Equalization with a Q of 1.4. |
| 5. Reduce to make background parts
more distant. Peak
Equalization with a Q of 1.0. |
| 6. Reduce to soften
"thin" guitar. Peak
Equalization with a Q of 1.0. |
|
7KHz |
| 1. Increase to add attack on low
frequency drums ( more metallic sound ). Peak Equalization with a Q of 1.4 to 2.8. |
| 2. Increase to add attack to
percussion instruments. Peak
Equalization with a Q of 1.4 to 2.8. |
| 3. Increase on dull singer. Peak Equalization with a Q of 1.0. |
| 4. Increase for more "finger
sound" on acoustic bass. Peak
Equalization with a Q of 1.4. |
| 5. Reduce to decrease "s"
sound on singers. Peak
Equalization with a Q of 2.8.
Sweep frequency slightly
(between 7 kHz and 8 kHz) to find the "exact" frequency of the S |
| 6. Increase to add sharpness to
synthesizers, rock guitars, acoustic guitar and piano. Peak Equalization with a Q of 1.0 to 1.4. |
|
10KHz |
| 1. Increase to brighten vocals. Peak Equalization with a Q of 1.0. |
| 2. Increase for "light
brightness" in acoustic guitar and piano. Peak Equalization with a Q of 1.0. |
| 3. Increase for hardness on
cymbals. Peak Equalization with
a Q of 1.4. |
| 4. Reduce to decrease "s"
sound on singers. Peak
Equalization with a Q of 1.4. |
|
15KHz |
| 1. Increase to brighten vocals
(breath sound). Peak
Equalization with a Q of 1.0. |
| 2. Increase to brighten cymbals,
string instruments and flutes. Peak
Equalization with a Q of 1.0. |
| 3. Increase to make sampled
synthesizer sound more real. Peak
Equalization with a Q of 1.4 to 2.8. |
|
|
| Frequency Octaves |
| Use the description of octaves to determine
where you want to set your equalizer's frequency control. Click here to open the description in another
browser window. |
| Equalization Techniques |
1 |
Boosting Harmonic Frequencies |
|
|
|
Boosting harmonics is one of the first
techniques an engineer learns to increase clarity and distinction on instruments. This is
a very valid method of equalizing. Some of the suggested equalizer settings from
equalization frequency chart used these techniques: |
|
Instrument |
Frequency |
Description |
Bass |
400 Hz |
"Increase to add clarity to
bass lines..." |
Bass |
1500 Hz |
" Increase for
‘clarity’ & ‘pluck..." |
Guitar |
3 kHz |
"Increase to add
attack..." |
Guitar |
5 kHz. |
"Increase
‘brightness..." |
Vocal |
5 kHz |
"Increase for vocal
presence." |
Vocal |
10 kHz |
"Increase to brighten
vocals." |
|
|
Notice that there are at least two
frequencies in the harmonic range of the above instruments that could be accented for
"clarity" or "brightness" |
|
|
2 |
Boosting Fundamental Frequencies |
|
|
|
The boosting of fundamental frequencies is
also one of the first things a new engineer tries, but boosting of fundamentals should be
the last thing ever considered. |
|
Accenting fundamental frequencies usually
makes the instrument indistinct and muddy sounding. The fundamental frequencies of two
instruments playing the same part are the same, therefore, accenting the fundamental of
instruments playing the same part makes both instruments closer to sounding the
same (indistinction). When two instruments are playing similar parts in the same key they
also get indistinct when the fundamental of either instrument is boosted. |
|
If an instrument sounds "thin" or
"small" one can carefully boost fundamental frequencies to correct this. The
microphone could have been poorly placed and/or the harmonics over-boosted with EQ.
Another application for boosting fundamental frequencies would be to do so when an
instrument was playing by itself (in solos etc.). |
|
|
3 |
Reducing Fundamental Frequencies |
|
|
|
Reducing fundamental frequencies in an
instrument tends to accent all of the harmonics and is a good alternative to boosting
harmonics. The method is most often used in rock recording but works well for all styles
of music. This technique found its way to the suggested frequencies chart: |
|
Instrument |
Frequency |
Description |
Bass |
40 Hz |
"Reduce to decrease
"boom" and increase recognition." |
Guitar |
100 Hz |
"Reduce to decrease boom and
increase clarity." |
Vocal |
200 Hz |
"Reduce to decrease muddiness
of vocals." |
|
|
|
4 |
Complimentary Equalization |
|
|
|
One of the hardest things to
overcome in mixing is the hearing limitation known as masking. Masking is one sound
covering up all or part of another sound because the frequencies of the two sounds are
close. The sound that is slightly louder sort of "wipes out" the other
sound. |
|
The way this works with music is that one
instrument will make the other instrument sound dull and indistinct. It is
frustrating to both the novice and the experienced engineer that an instrument sounds so
great by itself and so "lifeless" in the mix. |
|
An equalizer is a "level control"
for certain rangers of frequencies. When you boost a frequency with EQ, you are
making the dialed up frequency louder than others (as well as frequencies that are close
to the frequency set on the equalizer). When you dip or cut with an equalizer you
are reducing level of frequencies in that range. |
|
When you have indistinct sound between two
instruments, you can use a method called "complimentary equalization." The
idea is to boost a certain frequency on one instrument and dip that same frequency on
another instrument. This will get both instruments distinct, when properly done. |
|
Some key conflicts that come up often in mixes
include: |
|
Foot Drum Vs. Bass |
Dip between 350 Hz and 400Hz on the foot drum (to remove the
"cardboard" sound) and increase the same frequency on the bass (to add bass
presence). |
Lead Vocals Vs. Background Vocals |
Dip between 3 kHz and 4 kHz on the background vocals to give them
an "airy" sound and increase the same frequency on the lead vocal. |
|
|
When using this method you will be surprised
that you get a lot of change with only a little amount of equalization. Use between
3 dB and 6 dB of boost and cut. |
|
|
| A Typical Example: |
| The following example uses all of the
techniques discussed. instrumentation is Drums, Bass, Electric Guitar,
Keyboard with Lead and Background Vocals. "+" indicates boost and "-"
indicates reduction at given frequency. |
Instrument |
EQ Settings |
Notes |
Foot |
-6 @ 400 Hz +4 @ 5
kHz |
Reduces box quality. Increases
attack |
Snare |
+4 @7 kHz +2 @ 100
kHz |
Increases snap. Adds fullness
to high-tuned snare |
All Drums |
-4 @ 400 Hz +4 @
15 kHz |
Decreases ambiance & increases
bass clarity. Increases cymbal sizzle. |
Bass |
-2 @ 50 Hz +4 @
400 Hz +2 @ 1.5 kHz |
Increase clarity of bass Adds
clarity to bass line and recognition at low volume. Increases pluck and recognition. |
Guitar |
-4 @ 100 Hz +2 @ 3 kHz |
Increases guitar vs. bass
distinction. Increases attack ( 3 kHz needs much less boost once 100 Hz is reduced). |
keyboards |
+4 @ 5 kHz |
Increases clarity & brightness. |
Lead Vocal |
+4 @ 10 kHz +2 @ 5
kHz ? @ 200 Hz |
Brightens and adds presence. At 200
Hz, reduce 2 or 4 to add clarity to low vocals increase 2 or 4 to fill out high
vocals. |
Bkg. Vocal |
-6 @ 5 kHz |
Sets background back and increases
lead vs. background distinction |
|
| This "textbook" EQ can’t be
expected to work on all sessions. On the right session, however, it would give a
very natural sounding recording or mix with surprising clarity and punch. Notice
that boosting two instruments at the same frequency was carefully avoided. Notice
that reductions were generally larger than boosts. |
