Equalisation

Posted: Wed Apr 21, 2004 6:12 pm

Well this is a topic that a lot of you have been askin me about. It's hard for me to give you my own personal settings, so i decided to give you some basic lessons in EQ'ing. This lesson was adapted from my course work when I was doing my Music Production course 3 years ago.

EQ
Without any doubt, EQ is the most used – and abused – of all studio effects and it’s an essential part of virtually all types of synthesis. That’s because it works on a very important element of sound – the tone. In fact, at it’s simplest all EQ does is cut and boost certain frequencies of sound. Think of a hi-fi’s treble bass controls – they are basic EQ controls. But, of course technology has made EQ rather more sophisticated than that.

The good old days
EQ is short for equalisation. In the good old days of recording – we’re going back to 70’s here – the recording process was less sophisticated than it is today and it would typically lose the higher frequencies.

EQ was devised as a corrective process to boost higher frequencies to compensate for this loss during recording to make the recorded sound ‘equal’ to the original. That’s no longer the case with modern recording equipment and EQ is now used more than a corrective effect.

The human range of hearing is typically quoted as running from 15Hz to 20kHz, although this varies considerably from individual to individual. In practice, it’s generally not that wide, and we lose sensitivity to the upper frequencies with age and by listening to loud rock and dance music, so many people’s upper limit maybe closer to 15kHz

You might expect this ‘heard’ range of frequencies to be those you’d be interested in EQ’ing. However experiments have shown that frequencies above our normal range can effect our perception of the sound in subtle ways, so don’t ignore them.
The combination of frequencies is what gives a sound a distinctive tone, and when you equalise a sound you boost and cut certain frequencies which alters the tone.
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There are several controls typically used in filters and EQ effects

Cutoff frequency/Cutoff point: The frequency at which a filter comes into play and starts to affect the sound. This determines which part of the frequency spectrum the filter works on.

Attenuation: The opposite of amplification, it reduces the target frequencies

Level/Gain: A level or gain control enables you to cut (attenuate) or boost (amplify) a set of frequencies

Bandwidth/Q/Resonance: The range of frequencies that will be affected by the filter either side of the cutoff point. Defined n Hertz, the terms ‘bandwidth’ and ‘Q’ are most commonly used in recording circles. Bandwidth is the more useful term because it describes exactly what the control does. Resonance is particularly common in synthesis. It boosts the frequencies around the cutoff point and can be used to put the filter into self oscillation; not something you’d want to do in a recording environment.

deadzid · Posted: Wed Apr 21, 2004 7:13 pm Post subject: Soalan bonus...

So, can we remove those "hiss" noise (macam dalam kaset) just by adjusting the EQ? How?

GryMlock · Posted: Wed Apr 21, 2004 7:39 pm Post subject:

weih? i thought noise and hiss can be removed using the "noise reduction" tools?

Ridzi · Posted: Wed Apr 21, 2004 7:53 pm Post subject:

Boleh!! You have to find the target frequency (the frequency of the hiss) manually using a Parametric EQ.

A parametric EQ is an EQ where you can specify the exact frequency you want to cut/boost. The diagram i provided above is a simple 4 channel Parametric EQ.

To find the frequency that the hiss is coming from, on a Parametric EQ simply turn on 1 channel on (any channel pun boleh). ...then set the gain to a relatively low setting. See the diagram below - You can see I have set the Gain at -18dB, the Bandwidth at 2.4 and target frequency of 3348.0Hz

Set the Bandwidth/Q to a narrow setting - As you can see the curve jadi sempit or 'narrow' this is why its called 'Bandwidth'

Hiss usually resides in the high frequenciy registers, so play with the target Frequency in that area...and listen carefuly on-what-setting-the-hiss-disappears That would be the approximate target frequency you want to attenuate/cut. In the diagram below, I am playing with the target frequency. As you can see the curve moves up and down the spectrum (or left and right on the graph below)

Then adjust the Bandwidth/Q and the Gain again accordingly.. atau sesedap telinga ko mendengar....

thats how you can remove hiss manually...tapi kalau aku...aku pakai Dolby NR aje...sonang..hehehehe Dolby NR is basically an EQ with set Target frequencies....

/ridzi

GryMlock · Posted: Wed Apr 21, 2004 8:32 pm Post subject:

honestly, I didn't know how to use the damn parametric eq. read about it, every articles I read said that it's very usefull, but don't know how to apply em. well now i know one way of using it Razz

this is a cun tutorial ridzi.. thanks.
written clearly and straight to the point.

"tapi kalau aku...aku pakai Dolby NR aje...sonang..hehehehe "

part ni jek yg lain machiam ajer bunyi Evil or Very Mad

Ridzi · Posted: Wed Apr 21, 2004 10:28 pm Post subject:

Don't worry.... Next lesson will be about basic EQ'ing the basic band (guitars, bass, drums and vocals). I havent written them yet...but i am already sort of writing it in my head. which should keep me busy tonight after dinner - yes I dont have a life at the moment...hehehe

I guess i might as well use my dead time for useful purposes...i quite enjoy doing them anyway.. Smile

/ridzi

Bode · Joined: 03 Feb 2004 Articles: 10 Comments: 25

EQ, like any effects should be used judiciously to fix a problem. The saying goes that if it aint broken, dont fix it.
A good practice is to play a recording and fiddle and mess around as much as you can with the eq settings, so as to know for instance what is the difference between 2kHz and 3kHz. This will result in clever eq'ing, rather than blind eq'ing which will result in a bigger mess. When you already nail this skill, the next time you hear something which is not right in the sound you can almost immediately see the eq curve in your head and how to fix it. Another thing is, when in the studio, it helps to communicate using scientific terms...for instance, if my acoustic guitar sound is on the thin side, I can ask the producer/engineer to give a wide bandwidth boost of 500Hz by about 5dB from the top of my head and he can understand it right away...rather than use the terms like 'fatten' or 'beef' up the sound...which are rather ambiguous and lends itself to different interpretations.
Knowledge of eq also helps a lot when looking for guitar sounds. When I try a great amp in the shop, I can almost see the eq/gain/efx settings on my rig at home in order to replicate the same sounds....remember...sound is not just to be heard...try to 'see' it as well...
Oh yes before I forget...there are always many ways to achieve a specific sound. There are lots to be gained by cutting the gain as much as boosting. I learned that for instance, to make a sound brighter, you can get a slightly different effect by actually cutting the bass and low mids, compared to boosting the highs....experiment...think laterally..explore...

Ridzi · Posted: Thu Apr 22, 2004 12:01 am Post subject:

What Bode has said is absolutely true (sebenarnya aku lupa nak cakap hehehe Embarassed

) instead of boosting the frequencies that you want its better if you cut the frequencies that you dont want.

This is because boosting causes the track to become 'louder' and you wil have to re-balance the level/gain of the specific track you are EQ'ing.

Betul tak Doc?

/ridzi

Bode · Joined: 03 Feb 2004 Articles: 10 Comments: 25

Betuuuuullll....pandai adik aku nih! Very Happy