The ability to mix multiple audio sources together can add a dimension of versatility to your video productions.
Whether you call it a board or a console, an audio mixer can be one of the most flexible additions to your video production arsenal. Not only do mixers allow you to live-mix multiple audio sources during production, they also allow intricate post-production audio adjustments. Check out some of the features to look for when searching for the audio mixer that’s best for your needs. (These features correspond to the column headings in our Buyer’s Guide grid.)
Ins and Outs
Number of Input Channels: The number of possible sources available on the mixer. These can be any number of microphones and line-level inputs such as CD players, DAT recorders and microphones, just to name a few. Each input channel typically ties to a potentiometer (pot) that can adjust its gain (volume).
Types of Inputs and Types of Outputs: This dictates the type of equipment that attaches to the mixer without adapters. Balanced, 3-pin XLR connections are probably the most common connection used on mixers. RCA jacks (also known as phono jacks) are a common way to attach line sources such as CD players. Euroblock, multipin and TA3 connectors are also out there but are not nearly as ubiquitous.
Obviously, all mixers have a variety of inputs and outputs, which essentially define the usefulness and flexibility of a mixer. Of course, the size and cost of a mixer also increases with more inputs and outputs, so shopping is a balancing act.
Headphone-style jacks commonly come in two different configurations. The most common are unbalanced 1/4-inch connectors, like those found on less-expensive microphones. There is such a thing as a balanced 1/4-inch jack, but they are somewhat rare. They use the same connector as stereo headphones, but they carry only one channel of audio. In this configuration we refer them as tip-ring-sleeve or TRS connectors Finally, a few boards can handle 1/8-inch headphone-style mini-jacks that are generally found on computer sound cards and portable audio devices.
Number of Mono Inputs and Number of Stereo Inputs: This is the number of mono and stereo inputs on the board. It is a simple task to split stereo sources to two mono channels on the mixer if you need to.
Phantom Power on Microphone Inputs: If you use condenser microphones, you can power the mikes through a mixer’s phantom power connections. This feature isn’t as important if you use only dynamic microphones or if all of your condenser mikes have batteries, but it is a feature that’s well worth considering if you have plans for expanding your audio system.
Stereo Output: Whether the mixer can mix your sources down to a stereo program. This is an important feature to consider, but depending on the other equipment you’re working with, it may not be mandatory.
Meter Type: Whether the mixer has analog (needle-style) meters, digital (LED) meters or no meters at all. Analog meters are what some users are most comfortable with, but analog meters tend to over-emphasize some frequencies, giving readings that aren’t quite as accurate as they could be. LED meters are often not as graduated as their analog counterparts, but the color of the LEDs (generally green for normal range, amber for near-limit and red for over-limit) can give you a quick indication at a glance.
Microphone Gain Range and Line Gain Range: Given in decibels (dB), this is the range that the incoming signals are adjusted.
Overload/Clip Indicator: Whether the mixer can alert you that an incoming signal is too hot to deal with. If a source is clipped, you should immediately turn down the gain of that channel.
Number of EQ Bands: Specifies the number of bands (frequencies) of equalization that are available. A three-band equalizer might have separate controls for Low, Mid and High.
Cue: A cue monitor is especially useful if you’re live mixing, because it allows you to preview a channel without sending it out the main output channel.
Fader Type: Faders come in two main varieties: sliders and rotary pots. Sliders are generally preferred over rotary pots, as it’s easier to see how they are set; and they can slide up and down faster than the twist of a pot.
Auxiliary Send/Return: The auxiliary send/return allows you send mixed sound to external processing equipment, such as compressors, effect processors or amplifiers.
Once you connect your sources to the mixer, the board mixes and processes the signals using a variety of tools.
Battery Operation: Some smaller, battery-powered mixers allow you to take your mixer into the field for live mixing. This isn’t a necessary feature if you plan to use your mixer exclusively in the studio.
Dimensions and Weight: The size dictates where you can put the mixer and where you can take it. Naturally, you can’t put a very large mixer on a very small table.
Carry Cases: Portable mixers might have custom cases for the road.
The size of the mixer will also determine its usefulness. The needs of a solo-shooter in the field are quite different from those of a studio engineer.
Down with the Mix
Once you introduce a mixer into your audio production work, you may never want to go back to your previous setup. The versatility that a mixer gives you makes it an invaluable asset in your video production toolbox.