Eq 101

[e-vinyl]

I think EQ and compressing are the hards stages in the mix/mastering and

since sureno posted the "compression 101" thread ill leave here something

about EQ.

As you know sound is divided in frequencies.An Equalizer or EQ is used to

"change the volume" of a certain frequency wheter boosting or cutting it.
The goal of EQ is to correct or make equal (that is where the term comes)

certain frequency responses or to make "diferent sounds" as major

equalisation changes the timber.

They are very types of equalizers each one is best used on a determined task.
I will list a few types of equalisers:

Parametric equaliser - This equaliser is best used for accurate corrections

or on the mastering phase of a song/audio file.It has a line graphic showing

the frequency/gain.It is multi banded , this meaning that it has more than

one band of frequencies and it usually comes in 3,5 or 6 bands. It has 3

parameters:

Gain - This indicates how much you want to boost or cut certain

freqeuncy band.
Bandwidth or Q - It is the difference between the upper and lower

cutoff frequencies of or a signal spectrum. If added too much Q the line will

resemble and moutain , the less the Q and it will resemble a spike.
Frequency - The parametric Equalizer allows you to choose accuratly

the frequency you want to boost/cut.

Graphic Equaliser - this is the most common equaliser types of all, it isn't

as accurate as a parametric so it isn't used on cirurgical talks but it grabs

quite a punch :P. It is made out of sliders each with a static frequency

assigned to be controlled that usually ranges from 20hz to 20khz. The graphic

equaliser can go up to 31 bands (although it is still not as accurate as a

parametric).

Some mixers come with simple parametric equalisers which i do not advise for

major corrections.

Filters:

The filters are a type of equalisation which only a certain amount of

frequencies are maintained and the others are cut.

High pass filters : "passes" the high frequencies cutting off the mid and low

range.

Low pass filter : The opposite of a high pass filter.

Band pass filter: This filter has two cut off points: "above" and "below" the

desired frequency bands.

The audio spectrum ,according to what the human ear can hear can be devided

in 3 parts: low frequencies, mid frequencies and high frequencies.

The low frequencies can range from 20hz to +- 250 hz (below 20hz are

infrasonic sounds).

The mid frequencies range from 250hz to 4 khz.

Finally the high frequencies range from 4 khz to 20 khz (above 20khz are

called ultrasonic sounds).


Now i will list some equalising technics:


Shelving: The equal amount of gain for all frequencies above or below a

certain frequency.

Peak: Is a high Q boost on the mid frequencies.

Notch: Notch EQ is used to “notch out” or cut a narrow band of frequencies.


Fixing Common Mix Problems

On the mix the equaliser comes in handy when the instruments "saturate" some

of the frequencies causing it to sound all wrong.
A good aproach is to EQ the tracks/instruments individually rather than apply

EQ to the whole mix as it can ruin some good balance frequency distribution.
I will list some of the problems the mix can get:


Muddy: Possible cause:1- Build-up of low and low-mid information as a result of

the proximity effect from cardioid mics, too many tracks with extended

low-frequency material, or poor room acoustics.
2-Similar-sounding instruments competing for space in the

midrange.

Solution 1: Use a high pass filter on instruments/vocals who may have low frequencies and weren't supposed to (percussion, vocals, guitars, strings) to make room for bass guitars and kick drums.

Solution 2: Use diferent EQ settings on the instruments (for example with 2 guitars boost some of the frequencies on one of the guitars while cutting the same frequencies on the other so that they complement each other in the end).


Dull: Possible cause: Tracks with heavy mid-range presence that mask other instruments who sit on the high-end frequencies.

Solution: Use a low pass filter on the instruments that don't need a high frequency presence or cutting frequencies around 1-2khz.


Shrill: Possible cause: High frequencies being accentuated by one or more tracks.

Solution: Apply lowpass with a gentle slope to strident, overly bright tracks. If this isn’t enough, try making a slight dip in the 4–5kHz range.


Piercing: Possible cause: Ringing drum tones; resonant frequencies from room acoustics picked up by the microphone or spills (microfones intended for one job, recording instruments/voices/sounds that weren't supposed to).

Solution: Notch EQ with narrow bandwidth to reduce or completely cut out unwanted frequencies.


In the end you can still Equalise the overall mix but be careful as too much changes might ruin the mix. The art of Equalising uses mainly the ears of who is equalising so to make good EQ's resting the ears from time to time is advisable.


Sureno here it is with my own "flavor" thanks for the tip. I hope anyone finds this useful and sorry for my bad english.Enjoy

[sureno]

Very nice Mr e-vinyl, very nice indeed

[e-vinyl]

Thank you

[sureno]

Hey e-vinyl just letting you know iv hot linked this article to Eq in the glossary

[e-vinyl]

Originally Posted by sureno

Hey e-vinyl just letting you know iv hot linked this article to Eq in the glossary

thanks we got a new smiley or is it just me? :O

[sphelan]

I haven't read it all yet e-vinyl but nice input!