Every studio needs a console of some form. Whether the central nervous system of your studio has actual mass or exists in flat-panel cyberspace, hardware and software mixers share many features. Often, the controls are similar, but there are key differences. Hardware consoles interface with actual cables whereas virtual mixers shuffle digital audio around within the computer and include basic input and output indicators. Even if you've used drum machines, synths or other intricate gear, working with consoles in the beginning can be intimidating. A prerequisite to understanding consoles is a thorough knowledge of signal flow.
PLUG IT IN, PLUG IT IN
The primary role of a console is to enable an operator to mix and process a collection of discrete signals at the same time. Can you honestly look at your console or software mixer and know what each knob, input and button can do? That is the understanding of signal flow.
Inputs on various boards differ, and it is important to match the correct cable to the different connections for reasons of level and impedance matching. Inputs include balanced XLR jacks for mics, balanced or unbalanced phono (¼-inch) jacks for line-level sources, tape or phono inputs (often on RCA-type connectors), and auxiliary and effects inputs. Inputs on software mixers generally correspond to the physical inputs on the soundcard, just as the outputs correspond to the soundcard's outputs. Outputs on hardware consoles include the main mix, auxiliary sends, direct outputs, record or control-room outs, headphone jacks and submaster outputs.
One specialty connector on consoles is the insert. Inserts are single ¼-inch jacks on mains, individual channels and submixes, among other places. The jacks serve as inputs and outputs simultaneously. Inserts let you “tap” the signal with a single TRS plug that splits out to two plugs. These connect respectively to the inputs and outputs of external processing. The processed signal is then returned to the source before it is routed to the outputs. The special cables used are called send/return, or insert, cables.
MAJOR CONTROL ISSUES
With careful examination of boards, you can make a mental picture of the “pipeline” of signal flow. Now, turn your attention to the various controls of those signals. Volume faders are known as potentiometers, or pots (on hardware), and can be linear or rotary type. On both consoles and virtual mixers, mute and solo buttons are usually placed just above the faders. Mutes silence a channel in the main mix while allowing the signal to pass through to the headphones, as well as the auxiliary and monitor outputs. Solo buttons mute all other channels simultaneously, allowing you to hear one channel at a time. Be careful: This happens in the mains! Pan pots (or balances) are often just above the solos and mutes. By panning different tracks left and right, you can create a dynamic stereo mix.
Equalizers can vary wildly from mixer to mixer. Some consoles employ basic 2-band EQs with fixed-frequency treble and bass gains only. Top-notch mixers employ fully parametric EQs, in which both the center frequency and the width (Q) of each band are adjustable. Software mixers, on the other hand, often use plug-ins for their EQs. These can be extremely versatile, from fully parametric to 31-band linear EQs. Low-cut switches are also common on most boards. When activated, these cut out all frequencies below a certain frequency — normally 70 to 100 Hz — to eliminate rumble. Whereas EQ is used to dial in the tone of a signal, trim pots are used for controlling how loud the signal is — in other words, the preamplification of a channel. Trims are usually only found on hardware consoles and provide a sweepable gain of 40 to 70 dB. (They are not needed in software mixers; the recorded signals have already been preamped.) Some mixers also have pad switches, which instantly lower the level of a channel by a preset amount, usually between 10 and 30 dB. These are used to avoid internal clipping on unusually hot signals.
TRAINS, PLANES AND BUSES
The word bus in mixer terms can mean a number of things, but, here, the focus is on submasters, which are commonly called buses. These have their own volume faders. The main purpose of submasters is to group individual channels so that they can be mixed or effected together before being sent to the main mix. For example, in a live-band situation, you might use five mics on the drums but need to lower the volume of the drummer. This can be accomplished easily with one submaster rather than five individual faders. Or if you're mixing in the computer, you may want reverb on three tracks. Instead of using three plug-ins, route those tracks to a bus.
Auxiliary and effects sends and returns are another beast. These are used as extra outputs for a number of jobs, from feeding stage monitors or tape decks to sending multiple-channel signals to and from signal processors, such as delay or EQ (thus the name send/return). The more of these a board has, the more flexible it is. Finally, one more item deserves mention: phantom power. This switch exists solely on hardware mixers and is used for powering condenser mics. It typically supplies 18 to 48V of DC power through the microphone lines to the equipment that requires this power.
There are several more buttons, knobs and blinking lights on consoles that I haven't the room to discuss here, but this is a roundup of many of the most important items. Many great books on sound reinforcement are available, so grab one — they're fascinating, and you'll be glad you did.