The definition of an Equalization would be "the process of adjusting the balance between frequency components within an electronic signal" which was stated in Wikipedia. The function of an equalizer is to strengthen or weaken a certain frequency bands. With the help of an equalizer, the sound quality would be much more better. An equalizer is an important equipment in every studio.
The other uses of an equalizer is to improve an instrument's sound or to make it more prominent. An equalizer too can correct the problem caused by the room's acoustic condition which may cause by an uneven frequencies. Other than that, it can eliminate feedback during live concerts. Feedback are caused by frequency from the monitor which travel to the microphone thus creating an unpleasant sound. By using an equalizer, it can eliminate it by narrowing the bandwith of that certain frequency which will not affect other frequency components. Bandwith is known as the "difference between the upper and lower frequencies in a continuous set of frequencies" as what stated in Wikipedia.
Here's a tip for using an EQ. Do not over EQ or simply put EQ on any tracks. Yes, EQ is used to fix track problems or even enhanced the quality of a track but it does not change a character of a track. For example, you can't make an electronic guitar which is more suitable for rock, to sound like an acoustic guitar. All EQ does are cutting or boosting a certain frequencies in it.
For this topic, there's 5 types of equalization which is :-
Sweep/ Sweepable EQ
Parametric EQ is one of the best EQ in audio industry which cost more than other EQ would. What makes it special than the other EQ? It has a "Quality Factor" which is known only as "Q". This "Q Factor" can be widen or narrow at a certain frequency with such preciseness than other EQs could. As stated from Wikipedia as well, it has one or more section, "each of which implements a "second-order filter" which "attenuates higher frequencies more steeply".
Parametric EQ involves 3 adjustments which is the selection of the center frequencies in Hertz, adjustments of "Q" which determines the sharpness of the bandwith and lastly, the level gain control which you should determine weather to cut or boost the frequencies.
In-button are one of the button from Parametric EQ. It can be use for turning that particular EQ on or off. You can actually turn off the EQ band when you don't need to keep the changes that you made when you equalize a frequency instead of zero out the settings. Another button which is present in Parametric EQ are Shelf/Notch button. This button can be seen in the middle position of the mixer or console. The function of this button is to determine the shape of EQ when it is at ones end and it affect a set of range of frequencies. Parametric EQ has low pass filter and high pass filter. To put it simple, low pass filter boost the high frequencies which mainly consists of treble's sound while high pass filter boost for low frequency which consists of bass sound. This EQ too needs to cut holes in certain instruments. Every instrument needs to dominate it's own primary frequency range so that it will compliment each other. You can do this by cutting holes in your instrument.
How to use Parametric EQ
Firstly, the Gain Control button needs to be tweak. EQ has no effect without this button. The Gain Control determines how much frequency needs to be boost or cut.
After that, use the "Q" button to determine it's wide or narrow the EQ band is.
Other than that, choose a certain frequency for the band effect. It is better to pull down the frequencies instead of boosting them. It is because, when increasing the frequency, the plug-in needs to create extra noise which weren't there before. When cutting down the frequency, it is better to make it narrow and a bit deeper especially when there is no professional studio. As for boosting a frequency, it is better to make the frequency wider but shallower.
Earlier research (Rouse,2007) says that Graphic EQ "allows a user to see graphically and control individually a number of different frequency bands in a stereophonic system". This EQ has several function and one of them is to increase a certain frequency or could "decrease by a certain amount, generally up to 6 or 12 db". Other than that, by adjusting a certain number of frequency bands but limited to only frequency bands that your EQ has. It is advisable to not over EQ tracks as it may sounds worst even before the EQ process.
How to use a Graphic EQ
First of all, the EQ band needs to be set at 0db which is located at the middle on the knob. This will make the audio sound that came out of the monitor with no effect. Note, 0db is not silence. This will allow an original audio to be heard.
After setting the EQ in 0db, listen to the original audio first if it needs anything. Some may need to add a little bit of EQ and some may sound better in original than adding EQ.
The low or bass which usually starts around 20 is on the far left side of the unit and as for the high or treble which usually starts around 16k is on the far right side of the graphical EQ. As for the mid, it is between 400 and 1.6k.
After settling it, the EQ needs to be adjust accordingly. As mentioned before, do not over EQ as it might sounds worst than the original.
After adjusting the EQ, the next step is to adjust the level so that it won't be too loud.
"Most graphic EQ has two identical sets of filter, one for each channel in a stereophonic system".
Graphic EQ are mostly "potentiometers" which the gain control is adjust by moving the control button up or down.
These are some example of Graphic EQ product :-
Dual Channel 31-band Equalizer.
It has two 31-band which makes it a total of 62-bands and 1/3 octove.
It has a switchable boost or cut range of approximately 6 db or 12 db.
12db per octave 50 Hz low-cut filter
Front panel bypass switch
Approximately 12 db range input
4-segment LED ladders for monitory output levels
XLR and TRS inputs and outputs
Internet Torodial Transformer
BEQ700 Bass Graphic Equalizer ( Behringer ) - RM110.00
It is specially designed for bass guitar, even 5 and 6 string instruments.
It has a wide frequency ranges from 50Hz to 10kHz with powerful 15db boost or cut per band.
It can shape your sound and eliminate feedback with 7 band of equalization.
Status LED for effect on or off plus a battery check.
Shelf EQ "affects a range of frequencies above or below the target frequencies". In another word, by choosing a certain frequencies that you want to add EQ, it will affect other range of frequencies which is near the frequencies that you choose. Why is it call "shelf"? It is simply because of the shape of the curve itself. It has a "shelf" like curve. For shelf EQ, it's effect are on the frequency above or below your settings. This EQ are "good for enhancing or reducing high or low frequencies in your recording's mix".
How to use Shelf EQ
First of all, there's a low shelf and high shelf button in the EQ plug-in window which needs to be click. The low shelf and high shelf look like sideway tuning fork. As for the location of the high and low shelf button, it is located second from the left and second from the right above the EQ graph. There would be three parameters that needs to be adjusted in Pro tools and Logic which are :-
Gain - the amount of cutting or boosting that you apply to the signal.
Pro tools : It's either type in the amount into a text box next to
the shelf button or use the knob on the right.
Logic : Use a mouse and point it to the parameter control and drag it up for
boosting and drag it down for cutting.
Frequency - Frequency starts for the shelf
Pro tools : It is similar as gain. Type in the amount in the
text box or use the knob provided.
Logic : Again, similarly with gain which is to use the mouse and control the
parameters or click the EQ graph above the parameter to be
to be drag up or down.
The "Q" Factor - Controls the steepness of your shelf EQ. The curve of the shelf will be
more steeper if the number is higher as well. " The range of
frequencies affected to get the gain change of the shelf is narrower".
Pro tools : This too has the same control as both gain and frequency.
Type the amount into the text box. The type value range are between
1 and 2.
Logic : Control the settings by using a mouse as well but the settings can
be anywhere from 10 to 2.
Sweep EQ are also known as "semi-parametric" which sometimes incorrectly called as "parametric" because it too allows the control of bandwith which was stated by Barlett ( 2009 ). This EQ could be found on a medium priced desks. It has low and high frequencies which are usually fixed at 80Hz and 12Hz but it has one or two sweepable EQ. Those sweepable EQ could select a certain frequency at which the EQ operate. By doing this, it becomes more precise than any fixed EQ because you can choose a frequency that you want to focus on. As said before, they have two knobs, the first knob is to set the amount of gain you wish to apply and as for the second knob, you may select frequency you wish to effect. The reason why it is called "sweep" is because you can either cut or boost a higher or lower frequencies which makes it more precise over any kind of specific tone rather than letting a manufacturer set the frequencies for you.
How to use Sweep EQ
It is best to acquire original sound after recording. Listen to those sound and figure it out if it's need any changes. For example, if you need the vocal or any kind of instruments to have more highs or lows.
After deciding what to do, you will need to adjust the EQ. If you want a brighter sound, you will need to turn up the higher range. If you want more bass into the sound, you will need to turn up the lower range.
At a certain point all the way from the top to the bottom of the frequency range of the board, the high and low EQ usually boost or roll off frequencies but the middle is the sweepable button thus you can change the range that it affects as you wish.
After deciding how you want the sound to be, for example, you want the vocal to be heard when it was lost during recording or was overlapped by other instrument, you could make it louder. If you want a female vocal to stand out, you could set the sweepable midrange to a higher range.
After setting the range, you have to decide weather to cut or boost selected range with the mid range level knob.
Here are some of people's opinion and tips on how's the best way to dial in sweepable mid for live sound and also about other stuff.
"I usually boost the cut or boost knob just a bit and sweep the frequency dial. Depending on what you're doing sometimes you can find the bad sounding frequency and cut it out or sometimes you can use it to make the vocal or lead guitar cut through by boosting a particular frequency range. My motto is.. it's better to cut than to boost but there are exceptions. The best thing to do is to put on a pair of headphones and plug in a microphone and just play." ( Davidson, 2011 )
"Most vocal mics have some level of proximity effect ( 150-300Hz boost ) especially when the singer eats the mic. This boost can muddy up or cover the clarity of the vocal. Set the sweep at 200 and cut to about 10 o'clock or so and rock the sweep knob plus and minus the 200Hz to find the sweet spot that clears up the voice. Want to add some crunch in an electric guitar, dial in some 1.5K and boost to 2 o'clock, sweep plus or minus that1.5 and find the crunch factor after pleasing." ( Hurd, 2011 )
"Headphones during soundcheck would be very helpful in your specific situation. Also, go find a copy of Dave Moulton's Golden Ears audio program. It's a really useful set of drills pink noise and recorded music to help your brain associate the sound of a frequency with it's number on the dial." ( Cole, 2011 )
Filter EQ has been divided into two categories which are High Pass Filter which is widely known as HPF and Low Pass Filter which also widely known as LPF. Not only that, High Pass Filter are often called as Low Cut Filter and as for Low Pass Filter it is often called as High Cut Filter. Putting that aside, we will start by discussing all about High Pass Filter.
High Pass Filter
The function of High Pass Filter are for getting rid of the mud and rumble by letting the high frequencies pass and by blocking the low frequencies hence the name High Pass Filter. For example, an upright basses pick-ups can often generate rumble and mud along with bass tone that you desire. Why is this consider a problem? It is because the low lows muddy up the notes this dispersing the clarity of the sound. This can happen because the monitor is trying to reproduce those very low frequency which interferes with the note that we want the audience to hear. If you want to use these filter, it is best if you adjust the filter and tone control by using your ears rather than depending on numbers until you have good adjustment between thickness and clarity which is based from an author named Golihur (n.d). Before that, I would like to define the meaning of muddiness in an audio track. A muddiness simply means a sound or an audio which could not be heard clearly.
How do you use a High Pass Filter using Soundtrack Pro
To start of, you need to identify any low interference you want to remove in your audio. After you have identify, you need to select it and then go to Process. After doing that, you need to click Effect and find Single Band EQ.
From the Single Band EQ, select High Pass Filter which is located right above High Shelving EQ and below High Cut. "This Soundtrack Pro High Pass Filter will allow you to adjust the parameters of what you are filtering out, just not as much as a different type of filter".
After you have done that, begin by adjusting the frequency of High Pass Filter by determining the exact frequency that are caught and what are allowed to pass. You will also need to adjust the order and smoothing for how you want the sound to appear. You may also presets to High Pass Filter but these will be the ones you set yourself which is recommended as you may encounter common sounds that you have contact and may have been forced to deal with.
These are some tips on how to use High Pass Filter. First of all, it is best to limit the uses of High Pass Filter as well as for your overall amount. Only small amount is needed because it can make a big difference in the sound that could be heard clearly. This is specially true for music tracks that have high frequency range in tracks. By eliminating those very low frequencies, the rest of the sound will not be alter that much but no matter how much you limit the amount of High Pass Filter that is applied in Soundtrack Pro, an alteration will be made to the digital audio playback. All of this are stated by the author himself, Burley ( n.d ).
Low Pass Filter
Low Pass Filter's function is the opposite of High Pass Filter which is to get rid of unwanted high frequencies by letting the low frequency pass and by blocking those high frequency in an audio track hence the name Low Pass Filter. It is said that too much high frequencies may sound distorted and unprofessional. This was stated by an author named Ramsdell ( 2011 ).
This EQ are often use in a subwoofer. A subwoofer is "a speaker used in audio or home theater system for low bass in music or low frequency effects ( LFE) sounds in movie soundtracks." ( Altunian,n.d). Let me continue by telling you how to use Low Pass Filter for mixing and also on a synthesizer.
Uses of Low Pass Filter in Mixing
This was stated by the author named Islwyn (n.d).By using Low Pass Filter, you could eliminate unwanted high frequencies from any track when you are mixing different tracks of a song together. For example, by applying a Low Pass Filter on a screechy violin, it can mellow the sound. Other than that, also by using a Low Pass Filter on a recorded audio tracks that contain a lot of high frequencies, you can remove it from recording. Lastly, by applying a Low Pass Filter on bass or kick drum track, high frequencies would not conflict with the rest of the production.
Uses of Low Pass Filter in Synthesis
This too was stated by the same author named Islwyn (n.d). Low Pass Filter are use in Synthesizer to create bass sound. It is said to "set cutoff point on the filter fairly low, then increase the slope to add presence and punch". "Resonance" or "Res" are usually marked at the slope control on a synthesizer's Low Pass Filter. By using the synthesizer's envelope or low frequency osciallator to modify the filter's cutoff point which creates a pulsing sensation within the sound. In other words, it may create a more interesting bass sound.