General Equalization and Filtering Concept

General Equalization and Filtering Concept

           

              EQ or an equalizer is a vital tool in modern audio production.  Therefore, understanding the basic concept of general equalization and filtering has become very important to mixing engineers.  The followings are some basic knowledge of general equalization and filtering concept that the engineers must know.

An equalizer is a processor that is designed to change the tonal quality of audio passing through its process.   It operates by using a different numbers of filter circuits that have gain functions to audio signals of the specific frequency ranges.  The positive gain function is referred to “boost”, and the negative gain function is referred to “cut”. 

When we listen to sounds, louder always sound better, therefore, boosting frequencies will always sound better than cutting in the short run.  However, in the long run, cutting will create a more natural and cohesive sound. 

In addition, our ears are more sensitive to phase change during boosting and less sensitive when cutting.  Therefore, it is very important to apply as much cutting as possible instead of boosting, and in general, cuttings sound smoother than boostings.  Most of the time, cutting a specific frequency range will efficiently reduces a frequency masking and it will make the upper frequencies more apparent.

When boosting or cutting an audio signal, normally a wider Q or bandwidths are used in boost mode, while a narrower Q or bandwidths are used in cut mode.  Furthermore, sometimes instead of using a wider Q or bandwidths, using two narrower Q or bandwidths to distribute the load and focus on specific frequency ranges work better.

Lastly, when applying equalizer on a whole mix, the fundamental purpose should be to make sure that there is no excess or lack of frequency components throughout the frequency spectrum, and this is called, a “spectral management”.  In addition, using the solo function is only to help you identify some specific frequency component of a sound, therefore, always check the equalized sound within the mix.

Equalization always frustrates people, when they cannot feel the differences.  Always start with an extreme setting to identify the specific frequency range, then do the detail touch while listening the mix.  In addition, remember that when the frequencies are removed, it takes a moment for the brain to adjust.  Do not make an instant judgment.   

  

I Listen to Color

I Listen to Color

I can never imagine the world without colors.  This man has lived his life for years in gray-scaled world.  His name is Neil Harbisson.  Neil was born completely colorblind.  Everything he saw in the past was black and white until he invented the “electronic eye”, which is a device that allows human to identify colors by different audible frequencies.  After watching Neil’s video from Ted.com, I was inspired by his positive attitude toward his life even with disability and amazed with his invention, the electronic eye. 

It is not easy for someone to overcome his or her disability.  However, Neil never lost his faith and hopefulness. Now, he can perceive 360 different colors with his electronic eye, it is equal to the capacity of what humans can identify.  The camera lens detects the object’s color and translates to human ears in sine waves of specific frequencies.  It must took Neil a lots of training and time to finally be able to identify all the different frequencies, because even for sound and mixing engineers, it is hard to tell the exact frequencies of the perceiving sounds.  He explained that when he sees colors of paintings or art works, he hears chords of music through all the different frequencies that he captures.  He can hear a symphony of colors. 
              I think the electronic eye is a huge innovation in the entertainment industry because of the fact that it allows color-blinded people to feel and sense the art works through musical aspects.  It also might be able to work for blind people.  In art galleries or museums, they may not see the figures of image, however they still can sense the colors through their ears.  His innovation in the entertainment industry can further develop the artistic fields of our lives through expressing colors to sounds and may be vice verse.  He created the world where colors and sounds interact together by giving unity sensation to the audience.

Creating a Parallel Compression

Creating a Parallel Compression

A parallel compression is another useful technique that can enhance your mix.  It is also known as New York compression, because this technique was popular among the engineers from New York. 

A parallel compression can be used in many different sounds, but it is mostly used in the percussive aux tracks, such as drum sub-track.  The basic idea of this technique is to mix an unprocessed dry signal, or a lightly compressed signal with a heavy compressed signal.  The concept in this game is to reduce dynamic range by bringing up the soft sounds and adding details to it, rather than brining down the highest peak, which is the normal way we do to the dynamic processors such as compressor.

Once you have drums recorded in your DAW program, do a rough mix to it.  Try to get the balanced levels between each drum tracks.  When you have balanced levels between all the drum tracks, create two auxiliary tracks, and then name the each aux track as Drum Sub and P.C (parallel compression) Drum Sub. 

Send all the drum tracks to Drum Sub by setting the output of each drum tracks to the input of Drum Sub.  On the Drum Sub, you can lightly use compression on the insert if you feel like the recording has too much high peaks, but try to use the minimum.  

Then, you will send a copy of the Drum Sub to the P.C Drum Sub in unity gain by using the send parameter on its track.  Set the same bus on the send of the Drum Sub and the input of P.C Drum Sub.

Now, insert a compressor that you will like to use on the P.C Drum Sub.  We are going to process this compressor heavily to create vicious and nasty sounds.  First, set high ratio, commonly 8:1 or higher, then set a low threshold, which you can see more than -25db gain reduction.  The attack time should be fast, but for the release time, you will need to fairly adjust it by listening to fit the groove of music. 

If you mute the Drum Sub and only listen to the P.C Drum Sub, it will sound disgusting, because it is heavily compressed.  Leave the Drum Sub track at unity and set the P.C Drum Sub track to -∞, then slowly bring up the level of the P.C Drum Sub as you are listening.  This will be your wet and dry control for the parallel compression.  As you bring up the level of the parallel compressed track, you will notice more details in the quiet moments between each drum hits.      

  

Creating a Stereo Image using Haas Effect in Your Mix

Creating a Stereo Image using Haas Effect in Your Mix

When we record sounds, creating a stereo image is very important.  A well-made stereo recording or sound gives us a good localization image of the instruments and pleasure of music in three-dimensional.  A good quality of stereo imaging comes from the correct recording techniques of using two microphones.  There are many different recording techniques to create a stereo image, such as XY, AB, MS, and Blumlein recording.  However, if you failed to record using these proper methods, or you were only able to record with one microphone and do not have time to rerecord, do not be worried. There is a tip, which you can create a stereo image during your mix session.  Before we start talking about the tip, first you have to understand how our human ears perceive sounds.

Duplex Theory of Auditory Localization

            Localization of sound in humans is determined by the interaural time differences (difference in arrival time) and the intensity differences (difference in volume) of the same signal by our two ears.  These two principles form a duplex theory of auditory localization.  If a sound approach from the left side of the listener, it will arrives at the left ear first followed by the right ear.  In addition, it recognized to be louder in the left ear than the right ear.  Sounds directly from front of a listener will arrive at both ears at the same time and will recognized as same intensity in both ears.  If two exact signals come from left and right side in same distance and volume, our brain will perceives them as coming from center.  Our ear is more sensitive to time differences than the intensity differences.  In fact, we can perceive time differences that are small as 0.3 microseconds.

The Haas Effect

Many musicians and engineers think that panning is a solution for creating a stereo image.  However, panning simply uses the intensity differences of the sounds that only give you the positioning.  It does not give you the in-depth stereo image and spacious, which make you feel like you are in the live venue.  Therefore, the key in this game is using the interaural time differences.

            When we localize sounds, our brain gives priority to the signal that arrives at our ears first.  However, when these sounds are closely together, our brain perceives these sounds as a collective whole, rather than two individual signals.  This brain’s perception is called a Haas Effect.  This effect is limited to when the reflection signal is delayed less than 35ms from the direct signal.  If the delay between two signals is longer than 35ms, our brain perceives them as two individual identical signals.

             Let us create a Haas Effect in our mix.  For example, there is a mono recorded guitar track and we want to create a stereo image with this single track.  In order to create a stereo image using Haas Effect, first we simply take this track and duplicate it.  Make the original guitar track hard pan left, and take the duplicated track hard pan right.  Then, put a simple delay plug-in on the duplicated track, and slowly increase the amount of delay time on the plug-in while playing back the tracks.  You will feel the stereo image is getting wider as you increase the amount of delay time on the duplicated guitar track.  Now, we created a Haas Effect in our mix.  Theoretically, since these two tracks are identical signals coming from left and right in equal amplitude, our brain should perceives them as coming from center.  However, by slightly delaying one track, now our brain is thinking that a stereo signal is coming from left and right in wide range.  

            If you compare the track that only used a stereo panning and the track that used Haas Effect, you will hear the huge difference in the range of stereo image.  However, make sure you do not go pass 35ms, because if you go above 35ms, our brain will perceives these signals as two identical signals coming in with echoes.  In addition, you must be aware of using excessive amount of this effect.  Using multiple Haas Effects in one mix can cause too wide stereo spectrum, which makes you feel everything apart.  Also, just remember that using a Haas Effect is only a technique that can give spices to your mix.  The best way to create a stereo image in your mix is recording with correct stereo microphone techniques.