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The Value Of Frequencies

By June 27, 2012No Comments

Audio Spectrum

Our audio spectrum is divided into a range of 20 Hz. – 20,000 Hz. There are many instruments and vocals that must fit into this low to high audible frequency range. Some occupy the same frequencies within this band width. It is the engineer’s goal to have all instruments heard in the mix no matter what place or on top of what they lie along this domain.

Instrument Frequency Range

A cello has a range of frequencies that it occupies to produce its sound in its own way that makes it a cello. The instrument itself should be measured to see what that frequency range is and where on the physical instrument that sound radiates from. This will help us with microphone positioning. We want the low end to come through because that is the cello sound. However, there is still an upper register that must be heard and entered in our mix to complete the cello sound range.

Sound Location

When recording an instrument, find out the portion of the frequency spectrum that your instrument plays in. An acoustical guitar has many areas of sound generating surface. There is the lower area of the guitar That is called the body and that body is responsible for a guitar’s full sound that resonates from inside and outside the guitar body. There is also a middle section of the guitar that covers and portrays the fundamentals of the sounds generated from the guitar body. There is a upper area of the guitar that one hears the picking sounds from and also the string “zing” as it is termed. Air or note space is found in the very upper region of the guitar’s neck.

Frequency Slotting

Be careful with frequency slotting with a piece that has many players. After a time period and living with the track for awhile, you will begin to see where all instruments and vocals really fit to produce the sound that you desire. This knowledge will affect where you place things in the track and this also will become your personal style of recording that will appeal to some people but not others. Just make sure you are comfortable with it yourself. This is your sonic signature and will become the reason people hire you or do not.

Technical Sound Vs. Real Sound

To actually hear these differences in a recording, take a mike and record a guitar track that has finger picking in it. Do not use any EQ. Playback the track and use your EQ and give the track boosts throughout the frequency range of the guitar. Notice the differences in sound as you sweep through the guitar track. Do you hear the parts of the frequency response on the guitar that gives the guitar its body and fullness. Do you notice the frequency range where the guitar has more “air”. This is an important exercise because one can realize what part of the technical side of our recordings produces the sounds we like to hear and want in our guitar. When someone says give it more body or “air”, you will know where to go to get it.

Learn To Record Flat

It is very important to learn how to record instruments flat with no EQ. If you can master the art and science of recording flat you will be ahead of the curve when it comes down to final production. Thinking that one can “fix it in the mix” is not good thinking; garbage in, garbage out. By forcing yourself to record flat, you bring in many variables. You bring in the room, the artist, and the instrument into the equation. If you record a guitar and you get the mike too close to the sound hole, you will get a boomy sound which will blur and smear the middle and high frequencies of the guitar. It is in this frequency range that the real beauty of a guitar lies and one does not want to cover it up.

Fix It In The Mix?

If you try to “fix it in the mix”, you will cut the bass and you may or may not be able to achieve this goal. Your next step then since your mike was too close to the sound hole, is too work on the middles and highs. Unfortunately, if you crank up the highs, they will sound thinner than you want because the original recording was too thin with mids and highs to begin with. Make sure you get it correct from the beginning. It is easier to add 2 db or subtract 2db from a good recording than try to change the original sound with too much EQ. This is not something you will learn overnight. It is a process that takes many instruments and much time.

Begin With A Good Foundation

This process of starting with a nice flat recording will give you a good foundation line to work with. You will then need to refine your technique and start considering not only the instrument played but the song itself. Keep your arrangements free and open in the song so all subtleties can be heard completely. Make sure you can hear all decays and attacks of voice and instrument. Remember, you are after an emotion in the music you are recording and it is your job as engineer to find that emotion with the electronics during the recording process, but then take the electronics out of the playback presentation, so just the words and music come through and the audience can make that emotional connection to the music.

If you record instruments and vocals with no EQ to start, you will begin to learn about the instruments, mike placement, and the room. You will see how all of these factors contribute to the sound. You will develop your own style and form and people will come to you or not for work based on your individual techniques in the recording process. We all know people who are known for good drum recordings or good acoustical guitar recordings. They are no different from you or I. They have just taken the time to get it right with that particular instrument. It did not happen overnight.


I am a structural engineer as well as a master furniture maker. I design cabinets for low frequency, activated carbon absorbers. Connect with me on Google+

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