In the twenty-first century, the outboard mixer is no longer a necessity, although many people will always use one. In professional recording studios, outboard mixers are an essential, irreplaceable part of the studio. Even as technology continues to change, the outboard mixer in some form or another refuses to go away.

The word “mix” is defined as combining or blending into one mass or mixture. In the case of recorded audio, a mixer serves as a control over many individual sounds, or channels (tracks). A mixer has two uses: The first is to manage many inputs of sound and help to route them into the recorder, including setting the appropriate recording input level and pream-plifying microphones and instruments. The mixer can also be used after recording to provide balance and EQ, add additional signal effects, and provide a final master mix of your sound.

Do You Even Need a Mixer?

Twenty years ago, you had to have an outboard mixer, because there was no other way to control inputs to the recorder. These days, especially for home recording, you might not need one. For computer recording, every major brand of recording software provides a virtual mixer that allows you to change the balance of audio tracks and much more, all with your mouse. With a virtual mixer, you can even record the movement of the on-screen faders to be played back automatically during the final mix down (when everything is recorded to a single file) after you've finished mixing.

If you like the idea of moving volume sliders with your hands while using a computer, you can use “control surfaces” that move the onscreen faders. You can find more about control surfaces in Chapter 17.

Benefits of Using an Outboard Mixer

Even if you have the ability to mix built into your equipment, you might want a separate outboard mixer. Many computer-recording interfaces aren't exactly generous with the number of inputs and outputs they provide. Countless interfaces tout eight or more channels of simultaneous recording, yet they provide only two microphone inputs. So what do you do when you want to record more than two channels of microphones? In this situation, an outboard mixer is going to come in really handy.

Whether you use an outboard mixer or a virtual mixer on your computer, you'll have access to the same features. The virtual computer emulations do just that—emulate the hardware version. Computer mixers are designed so that an engineer who knows hardware mixers will have no trouble transferring her skills over to a computer.

An outboard mixer will allow you to take eight microphones and mix them down to a stereo (two-track) mix that you can bring into the computer. That works great for the computer interfaces that have only two inputs. The only downside is that you lose the ability to change the volume of individual channels after you record. Some studio and live recordings are still done this way.

For recording devices that give you only two microphone channels and additional line inputs, you can take advantage of the microphone preamps that many, if not all, outboard mixers have built in. You can plug in additional microphones to the mixer, preamplify the microphones, and send their individual outputs from the mixer to the line inputs of the recording device. This is the easiest way to increase the number of microphone channels. Not only can buying an outboard mixer be cheaper than buying a new recording device or additional microphone preamplifiers, but having one comes in handy if you play live or have to mix sound. A few companies, such as Mackie, Behringer, Alesis, Nady, Carvin, and Soundcraft, make small outboard mixers appropriate for home studios. Some mixers even incorporate a FireWire or USB connector, allowing you to use your mixer as a two-channel interface.