Glossary 293
Glossary
A/D converter—An electronic device for converting analog signals to digital signals.
AFL (After Fader Listen)—Monitoring signals after the channel fader. Contrast with PFL.
Aliasing—A type of signal distortion that occurs during A/D conversion if the sampling rate is less than twice that of the highest audio frequency. A/D converters employ aliasing filters to remove audio frequencies higher than half the sampling rate. See also Nyquist Sampling Theorem.
Anti-aliasing—In digital audio, a technique used to prevent aliasing in the form of an anti-aliasing filter before A/D conversion. This filter removes audio frequencies that are higher than half the sampling frequency (e.g., for a 32 kHz sampling rate, audio frequencies above 16 kHz are filtered).
Balancing—A technique for reducing interference in audio cables by using two con- ductors, known as the hot (+) and cold (–), to carry two versions of the audio signal, 180 degrees out of phase with each other. Since any interference picked up will be in the same phase on both conductors, the differential amplifier at the balanced input cancels out the noise, but amplifies the audio signal.
Bulk Dump—A MIDI function for transferring data between MIDI equipment. Data is transmitted as MIDI System Exclusive messages.
Bus—A common conductor used to collect and distribute audio signals.
Cascade—A technique for increasing the number of available inputs by connecting two or more audio mixers together.
CH—Abbreviation for channel.
Clipping—The unwanted distortion effect caused by inputting too large a signal to an audio circuit.
Coaxial—The electrical connection for transmitting and receiving consumer format digital audio, typically using phono connectors. See also Consumer format.
Consumer format—The consumer digital audio format, developed by Sony and Philips, for transferring digital audio data between consumer-type digital audio equip- ment, such as CD players, DAT, DCC, and MiniDisc decks. Two channels of digital audio (left & right) are carried in one connection, usually a phono connection. This format is also referred to as IEC60958 (formerly 958) and S/PDIF. See also Coaxial.
Control Change—A type of MIDI message providing real-time parameter control. Typical Control Changes include Modulation, Volume, Pan, and Portamento.
D/A converter—An electronic device for converting digital signals to analog signals.
De-emphasis—SeeEmphasis.
DIO—Abbreviation for digital input and output.
Dither—The process of adding low-level random noise to audio signals in order to reduce A/D converter quantization noise. Dither techniques are also used for digital audio wordlength reduction (e.g., 20 to 16-bit conversion).
DSP (Digital Signal Processor)—A chip designed specifically for processing large amounts of data at high speed and in real time. This type of processor is ideal for handling digital audio data.
Dynamic range—The difference between the loudest and quietest signal levels in a system. In an audio device, usually the difference between the maximum output level and the residual noise floor. In a digital system, the available dynamic range is deter-
