Most likely, you've never heard of a variable-gain amplifier or a gate or a compressor. The words "expander" or "limiter" probably sound Greek to you, too. But, it might be time to get familiar with these terms, which are actually audio components that the pros use to sweeten the sound of speech and music. Today, these audio components have plummeted in price, and many of these devices are available in the virtual world of computers. So, now almost anybody can own and operate one of these semi-obscure gadgets.
These gizmos are off the main highway of regular videomaking, down one of the side roads that musicians and advanced audio editors take. But, if you do a lot of music videos, or even industrial or instructional videos, these gadgets should be on your list, right after a reverb/echo/delay device and an equalizer. (See the article on reverbs and equalizers in the October 2002 issue of C&CV--Editor.)
Variable-gain amplifiers, or VGA, modify the dynamic range, the ratio between loudness and softness of sounds. Examples of VGAs are noise gates, expanders, limiters, and compressors.
A VGA is like a genie with his hand on your volume control. As the genie hears the sound coming into the VGA, he raises or lowers the volume of the output sound nearly instantaneously, and only for a moment. Depending upon the settings, the genie could lower the volume for a millisecond to take the edge off a certain percussive sound. Working just the opposite, the genie could raise the volume for just a millisecond, increasing the punch of the percussive sound.
In the first case, the VGA can tame the hardness of a drumbeat or the bump of a table during a conference. …