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.

In the recent internet publication, Recording Magazine, Robert Auld discusses the many benefits that headphones have over loudspeakers in our mixing or monitoring position. Lets summarize his positions and then discuss them.

No Room Sound

His first position is that they are not dependent on room acoustics. This is a true statement and headphones can be even be better than near field monitoring where we sit near field in an attempt to minimize the room sound. It is really only an attempt because we still have the low frequency issues in the room even though middle and high frequencies issues have been managed through our near field positioning.

Only One Driver

Headphones have one driver. Speakers or monitors have numerous drivers all connected with crossovers sending this frequency to one speaker and that frequency to another speaker. This is an unnatural electronic act which tries to duplicate the mono sound produced in nature by most sound generating devices such as animals. Animals generate full spectrum sounds within their given range through the use of only one “speaker” If you have multiple speakers in nature it always comes from many different animals speaking their respective part in the same time.

Mono Speaker – More Natural Sound

If you have ever listened to mono recordings played back through a full range speaker, you will know that there is a definite clarity and separation between the sounds. I had the pleasure in a movie theater in New York of having the music they play while you were coming in the theater and taking your seat, played through a single speaker positioned at center stage front. The sound was amazing and had an involvement to it that made me stare at the speaker as I was listening. I could not believe my ears.

Only One Polar Pattern

Robert also correctly states that there is no agreed upon universal if you will polar pattern for sound distribution from our loudspeakers. This is true. All hi-fi speaker manufactures I know, always take the sound distribution patterns into consideration and how these given sound energy from their design spreads out and interacts with the room boundary surfaces. With headphones you do not have this issue. In headphones, there is one speaker and there is no room for polar patterns to be an issue because there is no room in the space between the driver in the headphone and your head for any patterns of any type to develop except direct energy transmission from the headphone driver through the ear canal to the eardrum.

Some speakers have narrow fields of distribution. Some have more full and not so focused. Neither is right or wrong, they are just different design approaches that probably favor the designer’s tastes more than the consumers. If the customer likes the sound of a manufacturers speaker, he buys the designer’s idea of musical presentation in a small room scenario.

No Crosstalk

All of these issues like single speaker with no crossover, no room effects, and no multiple driver radiation patterns to deal with all contribute to what Robert calls lower crosstalk. With lower crosstalk, we have greater detail in the presentation and are much better able to access attack and decay rates in instruments and achieve high levels of separation in our vocals and instruments. Robert goes on to say that guys that record classical like headphones because of the fact that they can hear more and if an engineer can hear more, he or she stands a much better chance at having a better mix.

Inexpensive and Portable

Headphones are also reasonably inexpensive, light weight, and portable which lends themselves to use in many different locations and environments. You can not beat a good headphone/amp/converter set up fro high resolution detail and image. With all of this sonic exception comes cheaper pricing when one compares headphones to loudspeakers, especially hi-fi loudspeakers. Ease of operation combined with mobility, headphones do have a lot going for them.

Dynamic Vs. Electrostatic

With headphones we have dynamic and electrostatic headphones. Dynamic headphones can have open or closed backs. Therefore, we do not have much difference in the sound producing drivers as one uses a small driver and one uses a small strip of metal to produce the sound energy for listening. Bass energy is usually good with headphones and it is amazing to me that such low frequency energy can be produced with such a small driver. Although some headphones I have listened to still struggle with the low end detail and layering similar to what happens in small room acoustic situations where low frequency energy build up produces modal resonances.

Headphones do offer many advantages. We have a single, sound energy generating driver that produces a sound without the need for multiple drivers that have electronic crossover pathways to contend with. With a single driver we have no speaker polar dispersion patterns to deal with, only the direct signal from the driver to our ear canal. We have eliminated room sound because we have no side, front, or rear wall reflections to contend with. We tried with near field monitoring with speakers but we still get low frequency room sound. Clarity and definition are the strong points with costs and portability coming in a close second when one compares headphones to loudspeakers.