What Is A Broadcast Quality Recording? Part 7: Mixing Techniques
By Jerry Flattum - 02/03/2005 - 06:23 AM EST
What Is A Broadcast Quality Recording?
Part 7: Mixing
Mixers will vary on what they think is the hardest part of mixing, what instrument is the most difficult to record, and what effects to use and how much. Within the range of equipment options, opinions vary even more widely. A survey of 10 top recording studios will help provide a fairly accurate picture of necessary gear found in all studios.
Mixers use different techniques and have different styles. Afterall, they are artists; no different than the ones they’re recording. Mixing is very much like painting. In a nature painting, you’ve got a tree, a lake, the sky, and a couple of furry animals, whatever. Putting them all together is what makes the picture.
The picture could be a well-blended mix of everything, or, attention can focus on one aspect of the painting, like the furry animal or a sunset sky. Some mixers put an emphasis on the vocals, some on the song, some on volume. But, it’s common sense that a good mix is not when something is lost in favor of something else.
Mixing a bad song or bad performance probably causes more problems than anything else.
Achieving a Good Mix
Some mixers place emphasis on the singer while others place emphasis on the song. But a truly excellent mix does not favor one aspect of a recording over another. Being able to hear the words a singer is singing is obviously important, but not at the expense of a bass line, drum fill, or guitar riff. Preventing the arrangement from drowning out the vocals is of course a priority goal in mixing.
Despite the obvious need for a balanced mix, some engineers are guilty of cluttering up tracks with over-arranged, over-produced tricks that take away from the vocals, the song, or even the “feel” or “groove.” So artistically, a good mix is a balance of vocal, song, instrumentation, groove and feel. To accomplish such a mix without loosing subtle nuances is the real art and science of mixing...and mastering.
Favoring volume over dynamics runs the risk of ear fatigue and destroys the elements of a recording that make a song and/or arrangement special.
Goals of a Mix
The goals of a mix, other than an overall blend, are to bring out the highs and lows, so bass does not drown out high notes, or cymbal crashes don’t bury the vocals. It’s a balance between capturing the “feel” and the “rhythm” of a song/performance.
How a recording is ultimately heard played back calls for a variety of mixing strategies. Generally, most recordings are mixed for FM Radio. But a recording sounds different played on a home system than it does radio or on a portable CD player. Unless you are requested to mix for a specific situation mixing for CD and FM Radio is the safest approach.
Mixing and mastering is exponential. Each track, submix, overall mix, effect and frequency can be processed separately and together. You can divide a track into a range of frequencies. Then you can do the same for a submix and the final mix. Each F/X unit is divided into a range of frequencies. This allows for an infinite variety of processing possibilities. And the art of mixing/mastering is in knowing what affects one area changes another. This explains the very essence of the term “mix.” You are finding a balance in all areas of the recording: balancing the instruments in an arrangement; balancing the use of effects on individual tracks with effects used in the final mix and then once again in mastering; balancing highs and lows; balancing volume levels of individual tracks within a song and the collection of songs on a CD.
Rock and roll is notorious for not being able to hear the words a singer is singing. In some cases, when there’s extensive screaming involved, it’s impossible to hear the words. This makes sense in a live situation where the volume of the instruments drowns out the vocals. But in a controlled studio situation, a mixer has control over the volume of each individual instrument and track. So loss of vocal clarity might not be a mixing problem but a singing one.
In an age of superstardom, it is usually the singer who gets the most attention, not just publically, but in a mix as well. The vocals are mixed “up front,” meaning within the stereo field, the vocals are heard front and center at a higher volume than anything else in the mix. When vocals are used like instruments, an up front mix would not be the case.
It is generally the song—the melody sung by a singer—that defines a song and sells a song. But this focus is illusional. Strip away the rest of the instrumentation and there’s not much left to listen to. So, the concept of pulling a singer and melody out of context goes only so far.
Clearly, vocals are the most important part of any mix. However, not all recordings reflect this priority. The most common complaint in rock music is the inability to hear the words. Rock is notorious for favoring the sound of a vocalist over the lyrics.
Generally, the next instrument to mix is the bass. The bass and bass drum usually handle the bottom end, so punch, attack and clarity is important to prevent mud. It's quite common for less experienced engineers to make the low end sound too big. And of course, DJ's in clubs and guys trying to impress girls in their cars will boost the bass plenty. Some mixers account for this common sound alteration by keeping the low end relatively flat.
Balancing the low-end with high end, such as high-hats, which have little low-end at all, is by no means easy. Some mixers will solo the bass drum, bass guitar and hi-hat and do a submix before adding other tracks.
The Bass Drum
During the disco 70s, did producers and DJs just simply turn up the volume on the bass drum track? Or did the writing of the song start with a steady bass drum beat? Would what is normally called a disco song work without a disco beat? Is the beat implied in an acoustic rendering, meaning, the song is sung acappella, but the listener can “hear” the danceable beat underneath?
The word “tight” is often used to describe how instruments and vocals sit together in the mix. This is controled by spacial distances created by effects, EQ settings, and/or volume levels.
After drums, bass and vocals, other instruments like guitars, keyboards, strings and horns are added. Arrangements can be mixed according to the role instruments play. If a superstar horn section is part of the recording, it will be featured, as opposed to a horn section used as background fill.
Some engineers use variations on both mono and stereo mixes, depending on whether they are mixing for home stereo systems or radio. Home stereo systems are more dynamic, whereas radio broadcasts can suffer serious loss of dynamics. Sometimes the singles from a CD are mixed for radio while the other tracks are mixed for the home.
Volume plays an important role since certain frequencies, regardless of how good the mix, cannot be heard at low volume levels. When someone shouts, “Turn it up,” it's not always just because they are excited about their favorite song, but also because they can't hear all the ingredients that make that song happen (explore the Fletcher and Munson Effect). The human ear hears certain frequencies at certain volumes.
Mixing also alters our perceptions of how loud something is relative to something else. In life, shouting is obviously louder than whispering. But through a mix, a whisper can become a roar. Compression is often used to balance or favor out these inherent differences in volumes. Some mixers are compressor obsessed, compressing individual tracks as well as the overall mix. Other mixers abhor the use of compression to increase volume since it has a tendency to destroy dynamics.
Compressors, limiters, expanders and gates adjust the dynamics of a mix. Multiband dynamic effects are used to adjust specific frequencies. Single band compressors are applied to the full range of frequencies in a mix. Equalizers shape the tonal balance. Reverbs are used to create space for individual instruments and applied to the overall mix. Stereo Imaging effects adjust width and image within the stereo field. Harmonic Exciters add presence or “sparkle.” Loudness Maximizers increase loudness and limit peaks to prevent clipping. Dither provides the ability to convert higher word length recordings (24 or 32 bit) to lower bit depths for CD (16 bit) while maintaining dynamic range and minimizing quantization distortion.
For a guide on dithering go to iZotope Ozone.
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