Balanced Line

A circuit incorporating 2 wires to carry the signal voltage, wrapped with a shield that is grounded. This method is preferred over an unbalanced type line because it cancels any stray hum or noise that may be induced in the line from outside sources. An input or an output using an XLR is usually, but not always, balanced. A mono 1/4" phone plug is always unbalanced.

 

Equalisation 

The ability to adjust the tonal balance of a signal. This can be of a very broad nature, such as the bass and treble controls of a home stereo unit, or of a finely tuned nature, such as a 31 band Graphic Equaliser.

Fader

The channel fader determines the overall volume level of the channel. It is normally best to keep this fader at about 3/4 level for optimum headroom and lowest background noise.

 1/4" Plug

Also known as a phone plug, this is the common "guitar" type plug used on most electronic music instruments and amplifiers.

 

Feedback

Whenever a portion of an amplifiers output is returned to its input, and therefore re-amplified, a loud howl or squeal - i.e. feedback - is created. Most commonly, this occurs in sound systems when the output of the Speakers is picked up again and again by the Microphone forming a feedback "loop."

Mixer

A unit which blends several audio sources, such as microphones, CD's and tapes, together into a single mono or stereo output.

Headroom

The amount of available operating level before a circuit is overloaded and begins to distort.

PFL

Pre-fader listen. A type of solo, PFL allows the engineer to listen to the signal as it enters the console but before it travels through much of the circuitry of the console. Thus, if an overload occurs, the engineer can easily tell at what point in the signal path.

 

 

Phase Cancellation

The change in timbre that occurs when a signal partially cancels itself out. This frequently happens when a sound appears at a microphone at the same time as its reflection.

Gain or Trim Controls

A control on a mixer that sets or "trims" the input gain of the channel.

 

XLR

A mating male and female plug used for balanced operation and normally found on professional audio equipment. These are desirable because of their locking feature (making them difficult to accidentally disconnect) and sturdy construction.

Mute

Turns the channel off.