Audio-Visual Glossary



Q: In electronics, “Q” stands for quantity. In an equaliser, “Q” expresses how many frequencies are affected by an equaliser. The Q is usually adjustable. For example, when increasing the high frequencies (treble) with an equaliser, the “Q knob” can be rotated to affect many individual high frequencies all at the same time, or just a few. The Q is how many frequencies are to be affected by the equaliser’s other controls.


QC: Abbreviation for Quality Control, the checking and monitoring of product quality at each stage of production, including a final inspection and verification that the product is actually a VFP.


QOS: Abbreviation for Quality of Source. Refers to how good the original recording was to work with in mixing.


Q SURROUND: “Q-Surround” is a simulation of surround sound. Mainly intended for headphone listening, this is a quasi-surround mode that has been out for a number of years. It is included on some computer sound cards for listening to video games over one’s little computer loudspeakers or headphones. However, there have been some cd’s mixed with the Q-surround process which gave a panoramic effect to the sound.


QUADRAPHONIC SOUND: A 1970’s “stereo” system which involved the use of four speakers placed around the room to surround a listener with sound. Quadraphonic sound required that the music be specially mixed and released in the format. After it was introduced it rapidly died due to consumer disinterest.


QUAD SOUND: Same as Quadraphonic. (See QUADRAPHONIC SOUND.)






QUANTISE, QUANTISATION: The word “quantise”“ comes from the Latin word meaning “how much”. Quantise means dividing something into separate, distinct parts and assigning a value to each of those parts. Quantisation is what computers or computerised audiovisual equipment does to transform an analogue signal into a digital signal – they assign a numerical value to the analogue signal, moment to moment. Digital signals are not “mirror-images” of the physical universe. Rather, they are numerical representations of it. For example, if you lined up a group of children and had each count off “0” or “1” (every boy a “0” and each girl a “1”), you would have a “quantisation” of that group of children. The numerical representation (quantisation) might read as follows; 1001111010100111. You can now look at that quantisation and tell what the group of children consisted of (a girl, 2 boys, then 4 girls, another boy, a girl, a boy, a girl, two boys, and lastly, three girls). The quantisation is merely a representation of the children using two numbers, 0 and 1, which is the binary numbering system. In digital audiovisual equipment, the term “quantisation” means that the audio or video signal is assigned a value many times each second. An analogue to digital converter does this for any digital recording. For example, in producing a c.d., the audio is quantised 44,100 times per second.


QUANTISATION ERROR: A faulty conversion of the original sound, image or other data into digital information. “Quantisation error” is the difference between the numerical representation of an analogue signal and the actual analogue signal itself. This error can be heard (or seen) as noise and distortion.


QUANTISER: The electronic circuit inside a computer or piece of computerised equipment which transforms (converts) incoming signals, such as analogue audio and video signals, into bits of digital information. There are quantisers, for example, inside all analogue to digital converters. (See QUANTISE.)


QUARTER TRACK: A format in audio tape recording where each track (channel of sound) takes up 1/4 of a quarter inch tape’s width. Quarter track allows stereo recording in two directions on the tape, so one can have a side A and a side B.  


QUIESCENT CURRENT DRAW: The word “quiescent” means “at rest”. Quiescent current draw is how much electrical current from the wall outlet a piece of audiovisual equipment draws when it is idling (turned on, but not doing anything). For example, an audio power amp left turned on, but not producing any sound over loudspeakers, has a certain amount of “quiescent” current draw.


QUESTED: A loudspeaker and audio amplifier manufacturing company in England that specialises in making loudspeakers for professional studio use. Owner and designer is Roger Quested.


QUICKTIME: QuickTime is a computer program that is used often in the filmmaking industry to rapidly review film footage shot for a film in progress or any other footage to be rapidly reviewed for suitability. An entire movie can be presented in QuickTime. It is a computer program from Apple Computers that is part of the Mac Operating system.