What is an Audio Mixer?
An audio mixer is an electronic device that channels incoming audio signals while maintaining control over such effects as volume level, tonality, placement, and other dynamics for music production. In professional sound mixing, this device is sometimes called a soundboard (sound board), mixing console, or mixer.
Traditional audio mixers are physical pieces of equipment with inputs for instruments and digital devices such as drum machines, auxiliary line-ins, and microphones. Mixing technology is also available via software, but requires an advanced sound card that features instrument inputs. Alternately, a person can transfer pre-recorded tracks to a computer for use with audio software.
Modern digital mixers are made for both professional and nonprofessional use, covering a wide range of quality and price. Studios commonly use a dedicated one, while in the nonprofessional market, it is often coupled with a digital recorder. The least expensive, nonprofessional models feature 4-track digital recording with built-in mixer. Additional channels add to the price, all else being equal, with high-end models featuring 24 channels.
Each channel on a mixer or soundboard is dedicated to a separate track, such as one channel for drums, one for lead guitar, rhythm, bass, keyboards, and so on. By keeping each instrument on its own track, channels not only stay clean of artifacts, but the sound engineer has maximum control over every element and aspect of the project.
Even after a track is recorded, the volume, echo, reverb, equalization, and various other effects can be applied as needed to tweak the sound. When tracks are played through the audio mixer simultaneously, the engineer can adjust or manipulate individual instruments or vocals to get the blend just right, as each channel has its own “lane” of controls. If drums overpower the mix at some point, they can be leveled down. If the lead guitar is buried, it can be brought out front. If vocals are muddy, they can be brightened.
A good audio mixer also features panoramic potentiometers otherwise known as “pan pots.” This control places an audio track to the left, center, or right within the mix to create a full stereo image. Traditionally, vocals are centered, with lead and rhythm guitars taking up opposite ends of the mix, and drums filling the background. This builds an acoustical environment, as if the band is surrounding the listener. Keyboards, percussion, and other instruments are also carefully placed within the image. In some instances, a drum roll or lead riff might “slide” or “roll” (pan) from one stereo channel to the other for effect, creating a sensation of movement.
In music production, the drum track is typically produced first, providing the foundation on which to build the other tracks. Once a second track is finished, it can be “bounced” to the drum track to free up another channel, and so on. Though there are limits to how many tracks can be bounced, even an inexpensive 4-track recorder with a built in mixer is generally capable of producing eight tracks or more. In all cases, the end result is mixed down to a 2-track stereo recording known as the “master,” from which a compact disk can be made for duplication.
Musicians who play at home and would like to record and produce their own original music may find that a mobile, palm-sized 4-channel audio mixer can be sufficient for the job. Some models come complete with built-in digital bass and drum kits for accompaniment, and an array of guitar effects. These affordable audio recorder/mixers won’t have the capability or control of larger, more professional models, but they do have astounding feature sets for their class. Some models use flash cards for unlimited memory, and many models offer universal serial bus (USB) or Firewire® ports so the final mix can be more easily transferred to a computer for burning to compact disk.
If the musician would like something with greater editing features, 8-16 track digital models might be a better choice. A mixer, recorder, and burner in one, the person can lay down his or her tracks, mix them, and burn the master to CD with a single machine that’s half the size of a laptop and a fraction of its weight. A similar but less expensive model will not include the burner, and the user can transfer the music to his or her computer to burn it.
A 24-track audio mixer is generally more soundboard than the average person needs, though standard in studio production. As expected, these models can cost a great deal of money, though a low-end model can be had for less. Before a musician purchases one, he or she would be wise to check for professional reviews along with consumer reviews.
@gravois - It is indeed. Each one of those knobs, buttons and sliders controls a different input. Tweaking any of them in the slightest way can change the qualities of a sound significantly. Production has gotten so sophisticated and complicated that audio mixing boards are now the size of dining room tables. I can't wait to see what they look like it 20 years.
On MTV I always see guys sitting behind huge tables filled with knobs and sliders. Is this an audio mixing board?
@chivebasil - So true. As someone who has both produced albums and been in bands who have had our albums produced, I can attest to how hard it is. There is not a magic button you press to make your album sound big and bold, the effect is accomplished through the careful manipulation of hundreds of different variables that change throughout the song. It can be a long, frustrating, and extremely labor intensive process filled with a lot of trial and error. It is not for the impatient.
@jonrss - Great point. If you read the liner notes you will see that most band either jump around between producers or stick with one through their entire career. That is because the producer is responsible for what the band will sound like when their songs are captured on record.
Are they going to be big and epic, dark and distant, muddy and grungy, crisp and bright, reverby? There is literally a million different approaches a produced can take when they are trying to establish a bands recorded sound. It is both an art and an incredible technical achievement.
I remember when I first figured out exactly what audio production meant. Up until that point I had always figured that a band wrote a song, and then recorded a song and that was pretty much what you heard when you bought the CD.
But there is so much more going on and often times the producer is like an unofficial member of the band. I had this big revelation when I was listening to Joy Division. Me and my friends had learned to play Transmission, but somehow our version never sounded like the one on the CD.
That is because the album track has careful production that makes it sound darker and more filled with echoes. We were playing the same notes as the band, but we didn't have a producer and a mixing board to give the song that haunting effect.
Audio mixers are so cool because they serve a purpose that is both practical and artistic. On the one hand you need to have a well mixed piece of audio just so you can hear everything. You do not want to bury the vocals so that they are impossible to hear or crank the base up so much that it drowns everything else out.
But once you establish a baseline mix that sounds pretty good, an audio mixing board can be used to embellish and accentuate the sound of your recording in lots of interesting ways. Maybe you want to have a quiet and distant drum track, or a blast of vocals, or a guitar solo that fades in and out, all of these can be accomplished by simply adjusting the levels on a mixing board. This simple machine can elevate a song to the level of composition.
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