Audio T | Key Word | Glossary of Technical Terms

Glossary of Technical Terms


  • 4K RESOLUTION - Displays with a resolution of 3840 x 2160 pixels or an 8 Megapixel image, giving 4 x the resolution of current 1080(Full HD Screens). ?
  • 8K RESOLUTION - Refers to an image or display resolution with a width of approximately 8,000 pixels. 8K UHD (7680?×?4320) is the highest resolution defined in the Rec. 2020 (UHDTV) standard


  • AAC - Compressed audio format, largely used by Apple that sounds better than MP3 for a given bitrate, though fewer products use it.
  • ACTIVE SPEAKER - design in which the crossover, used to split frequencies between the drive-units, is located before the amplification. Each drive-unit, or group of drivers (e.g. for bass or treble), then has its own dedicated amplifier. Not all 'active' speakers are fully active: some are merely conventional speakers with amplification built-in, which really should be termed “Powered Speakers”.
  • AIFF - (Audio Interchange File Format) Apple terminology for CD-quality files. Uncompressed 16-bit/44.1kHz music is stored on Apple computers as .aiff files.
  • AIRPLAY - Apple's solution for audio and video streaming between its portable devices, computers running its iTunes software, and third-party components enabled for the service. Using it, music can be streamed over a home network to a connected audio system or, via the Apple TV device, video and audio can be streamed directly to a television.
  • ALIGNMENT - Most commonly used to describe positioning the cartridge within the head-shell of the turntable. There are many different alignments, all trying to achieve the lowest distortion across the playing surface of the record. It is crucial that this is accurate and an “Alignment Protractor” will be used to exactly line up the cartridge as the position will vary in the head-shell depending on the arm/turntable combination.
  • ANALOGUE - The original way of storing audio data, as used by LPs and cassettes.
  • APP - Short for 'application': small piece of software available for download to add functionality to a device, usually at relatively low cost if not for free. For example, various consumer electronics manufacturers now offer control apps, able to be downloaded from Apple's iTunes Store to iPods, iPhones and iPads, to control items of equipment such as Streamers and Hi-Fi systems.
  • APPLE LOSSLESS - (aka ALAC) audio compression format from Apple: has the advantage of (theoretically) identical sound to uncompressed audio, while reducing file size; has the disadvantage of being a proprietary Apple format, and thus not playable on some network devices.
  • ARC - (Audio Return Channel), a convenient way of getting audio from your TV, back to your amplifier using the HDMI connection to the TV, requires equipment to be compatible though.


  • BALANCED CONNECTION- A type of audio signal connection designed to reject noise, particularly over longer length cables, hence its popularity in professional applications. This type of connection can be used for both analogue and digital connections in the hi-fi world, although it is relatively uncommon and uses XLR connectors normally.
  • BASS REFLEX - A Speaker design using airflow from a port in the cabinet to help deliver extended bass reproduction.
  • BI-AMPLIFICATION - (or bi-amping) Each drive unit of a speaker is driven by a separate amp channel, so a pair of two-way speakers needs two stereo amps and two runs of cable to each speaker.
  • BITRATE - The measure of the quality of a digital file, in units of kilobits per second. However, simply having a higher bitrate doesn't guarantee better sound as the encoding format also plays a major part, but on the whole bigger is better!
  • BI-WIRING - Is thought by some to give some of the benefits of bi-amping, but at lower cost. You need suitable speakers (with two sets of inputs and a split crossover), then send twin runs of cable from the same amp to each loudspeaker.
  • BLU-RAY - Digital disc format aiming to provide a higher-quality successor to DVD. Blu-Ray offers a high-definition image and less-compressed sound than DVD.


  • CARTRIDGE - The device that plays a record. It converts the undulations in the record grooves into electrical signals for an amplifier to boost up.
  • COAXIAL DIGITAL - A digital audio connection, using 75 ohms interconnect cable. Can be terminated with either conventional phono plugs or locking BNC connectors.
  • COMPRESSION - The process of squeezing data files to make them smaller, sometimes by discarding some of the musical information to make the files more portable, a “Lossy” compression system like MP3 uses this as opposed to FLAC and ALAC which are “Mathematically” compressed so they can be restored to their full glory, like a computer ZIP file for example.
  • CROSSOVER - A circuit designed to split the incoming signal, sending high frequencies to the tweeter, and low ones to the woofer.


  • DAB - (Digital Audio Broadcasting) or digital radio in the UK.
  • DAC - (Digital-to-analogue converters) change digital strings of bits (i.e Digital/Optical Outputs) into analogue audio that can be amplified and reproduced through loudspeakers.
  • DECIBEL - (dB) Measures sound pressure. A change of 1dB is just about audible, +10dB is a doubling of level.
  • DECODING - Blu-ray soundtracks usually include multichannel audio eg Dolby HD or DTS Master Audio. You need a processor or AV amplifier to decode the data and pass it on to your speakers.
  • DHCP - (Dynamic Host Configuration Protocol), the system by which all devices including computers and music streamers etc, on your computer network are automatically assigned an IP Address, or location if you like, where it can be found by others.
  • DIGITAL - Digital data is stored in bits – as on/off signals (or pulses), able to be transferred with little overall loss of quality.
  • DLNA - The (Digital Living Network Alliance), an organisation set-up by leading consumer electronics manufacturers to ensure compatibility between components, for example for the streaming of audio and video between computers and components such as TV and Blu-ray players (see also UPnP).
  • DOLBY - A company whose technology is used to encode the multichannel soundtracks for films, which get transferred to Blu-ray and DVD.
  • DOLBY ATMOS - A surround sound format launched in cinemas in 2012 and then for home use in 2014. It adds overhead sound effects to the already established 5.1 or 7.1 channel layouts. At home it is achieved by adding 2 or 4 overhead ceiling speakers or upward firing traditional speakers to bounce sound off of the ceiling. This adds a new dimension to the sound with airborne effects actually flying over your head for much greater realism and immersion. New decoding equipment is required along with material carrying the Atmos soundtrack. The good news is that older equipment will play the new Atmos based material as normal 5.1/7.1 channels.
  • DTS - Like Dolby, DTS is a system for encoding audio on to movie soundtracks for playback on compatible AV receivers.
  • DYNAMICS - The range in decibels between the largest and smallest audio signals reproduced by hi-fi, or stored on a recording.


  • ETHERNET - Commonly accepted term for the IEEE802.3 standard for wired Local Area Network (LAN) connections between devices, using simple twisted-pair cabling, often referred to as Cat5 or Cat6 and terminated in standard RJ45 plugs. The type of cable used to plug your computer into your broadband router. Although replaced by Wi-Fi wireless networking in many homes, Ethernet can give much more reliable connectivity for the streaming of music.


  • FLAC - (Free Lossless Audio Codec). An open-source (i.e. free) audio coding and decoding system, using lossless compression to reduce file sizes, theoretically without loss of quality (though some feel they can hear a difference between music stored in FLAC and uncompressed CD-quality WAV files).
  • FRAME RATE - Films on Blu-ray are produced at 24 frames per second, PAL TV at 25 frames per second and American Video at 30 frames per second. Your TV must handle all these to keep motion natural and most current TVs have this capability.
  • FREEVIEW - 70-plus TV and Radio channels including HD broadcasts available for free using a normal aerial. One of the main platforms for the digital TV switchover in the UK.
  • FREESAT - The satellite equivalent of Freeview offering over 150 free TV and Radio stations including HD channels using a dish in the UK.
  • FULL HD - Whereas HD uses 720 horizontal lines of picture, Full HD uses 1080. It offers even more detailed TV images.


  • HARD DRIVE/DISK - This is a device for storing large quantities of data. Hard disks first appeared in computers, and are now found in MP3 players (for audio and photos), set-top boxes, DVD recorders (for video and audio), and network music servers.
  • HDMI - (High-definition multimedia interface) A High-quality digital video/audio connection used between Blu-ray and DVD players and AV amplifiers and Displays. It is able to carry multichannel high-resolution audio as well as digital video and now has a return for TV tuner audio, see ARC.
  • HIGH-RESOLUTION AUDIO - Usually understood to mean any audio format beyond the 16 bit/44.1 kHz Compact Disc standard. Common high-resolution formats which should offer better sound quality include 24 bit/96 kHz and 24 bit/192 khz. However these require special players to handle them, including some streaming players and even a few amplifier/receivers. As with all things matters can be confused in this case by internet streaming services offering 'HD Radio' for example. At 320kbps this is not HD Audio as we expect it, but is 'higher definition' than most existing web-streamed services (and indeed DAB) but not actually better than CD quality.


  • IMPEDANCE - A low impedance draws a high current from the source, while high value impedance draws a little. Loudspeakers or headphones with low impedance are likely to be more difficult to power. Bear in mind that the impedance figure given by speaker manufacturers is usually a nominal one and that impedance can vary with frequency, to a greater or lesser degree depending on the speaker design.
  • INFINITE BAFFLE - Describes the mental state of an individual before reading this Gobbledegook Decoder and to a lesser extent a type of speaker cabinet design without bass ports, forming a sealed box instead.
  • IP ADDRESS - A unique identifier for a device on a home network that enables other devices to find it. Think of it as being like your house number within your street for example. On many home networks IP addresses are assigned dynamically according to the order in which components are connected, using something called Dynamic Host Configuration Protocol, or DHCP: this can cause problems if an item is turned off and then on again or disconnected and reconnected. For example, in a streaming music system the player may find that the network music storage is no longer where it 'expects it to be' – i.e. its IP address has been reassigned by DHCP – and so music can't be played. It is the same situation as if your neighbour ran across the street and moved into another house when you were out, then the next time you knocked on his usual door he would not be there! The solution is to assign, a static (Fixed) IP address to crucial components on such a network, so they can always 'find' each other.


  • KBPS - (or Kb/s Kilobits per second). This is either a transfer rate – how fast data can be piped down a cable – or, more commonly, a compression rate: how much data has been retained when a music track (e.g. an MP3) has been compressed. A higher figure means larger files, but usually better sound.


  • LINE LEVEL - Inputs that don’t need additional amplification/equalisation before a preamplifier can handle them. For example, the analogue output from CD players, radio tuners, etc.
  • LCD - Along with plasma, the main flat screen TV technology. LCD is the dominant type for sets with screens up to 40in. Picture quality is improving with the addition of LED backlights. Similar technology is used for many projectors.


  • MC CARTRIDGE - A moving coil cartridge.
  • MM CARTRIDGE - Moving Magnet Cartridge
  • MP3 - Audio compression for music files. Can reduce file sizes up to a factor of 10 compared with CDs, but can also reduce quality.
  • MQA - stands for Master Quality Authenticated, which is a codec using lossless compression and a form of file fingerprinting intended for high fidelity audio internet streaming and downloading.


  • NAS - A (Network Attached Storage) device: a hard-disk storage unit connected to the router for a home network, allowing its content (music, video, pictures, other files) to be accessed by any computer or other device on that network.
  • NETWORK SERVER - Stores tracks from a large number of CDs, in a variety of formats such as AAC,ALAC,FLAC,MP3 and WMA, so they can be piped around your home.
  • NETWORK PLAYER - Connects to a router or a network server via Wi-Fi or Ethernet, and allows you to access music or video files stored on your network, most likely on a computer or NAS drive in your home.
  • NFC - (Near Field Communication), mainly used in Home Entertainment circles to enable the simple “pairing” of streaming devices by simply touching them together, with the same action to disconnect.


  • OLED - (Organic Light Emitting Diode) Upcoming flat screen technology will combine the high contrast and fast response of Plasma screens with the high brightness of LED. Currently in its infancy as far as large screen technology goes with high cost and unknown long term reliability. A very exciting technology, one day your TV might roll up when you are not watching it!
  • OPTICAL DIGITAL - A digital audio connector, using light to transmit data down a transparent fibre, sometimes made of glass, but more usually plastic. (See Coaxial.)


  • PAL - (Phase Alternating Line) the European system of TV broadcasting.
  • PCM - ( Pulse Code Modulation) Digitally stored, uncompressed audio, as used by CDs. Also available as a soundtrack option on some Blu-ray discs.
  • PASSIVE LOUDSPEAKER - The most commonly available speaker type, where an external amplifier is used to power the loudspeaker and the crossover is built into the speaker cabinet.
  • PHONO STAGE - A turntables cartridge outputs signals at a much lower level than a CD player so it needs extra amplification from a phono stage as well as audio equalisation to the RIAA curve. Some amplifiers have them built-in.
  • POWER AMPLIFIER - Increases the level of audio signals from a preamplifier to a sufficient level to drive loudspeakers.
  • POWER-HANDLING - The highest safe power for speakers. Note: it’s easier to damage speakers with an amplifier of low output power driven hard, than with a high power amplifier working well within its limits.
  • PREAMPLIFIER - The control part of an amp, allowing input selection, possibly tone control and of course volume. Built into integrated amps, but can be separate and used with a power amp or active speakers.
  • PROGRESSIVE SCAN - is the term to describe creating a TV picture on screen in one hit, writing all the lines of picture information at once rather than writing alternate lines and relying on persistence of vision, effectively fooling our brains, to build up the whole picture as in interlaced TV scanning. This method gives clearer, flicker-free images. Blu-ray is capable of delivering 1080p (1080 lines, progressive scan), while HD TV via satellite or terrestrial platforms is 1080i (interlaced) at best.
  • PROJECTOR - currently the best way of achieving a cinematic image at home, requires a dark environment to give its best, usually a ceiling mounted device that illuminates a large fixed or retractable screen from across the room, just like an actual cinema!


  • RIAA EQUALISATION - (Recording Industry Association of America) During the production of vinyl records the bass content of the recording is reduced and the treble content boosted prior to transferring the recording on to the vinyl itself to improve playability and quality. This means that on playback the reverse must happen. The phono stage will not only amplify the tiny signal from your record player but also reverse the changes applied when making the record according to the RIAA equalisation curve.
  • RTFM - Refers to making sure you have read the flipping manual before deciding your kit is broken!


  • SENSITIVITY - Most likely used to describe how much output a loudspeaker can produce in Decibels when measured with 1 Watt of input power at a set distance of usually 1 metre, for example 89dB@1m.
  • S/PDIF - (Sony/Phillips Digital Interface) is aq type of digital interface used in consumer audio electronics.


  • THX - A set of standards for home cinema that should ensure a certain quality of sound. Equipment and software (i.e. DVDs/Blu-rays) are submitted to THX for testing to ensure they adhere to the standards the company sets, but that's not to say products without the THX certification are any less capable.
  • TRACKING WEIGHT - The downward force applied to a turntables stylus when playing vinyl, adjusted by moving the counter-weight at the rear of the arm. Each cartridge will specify the optimum weight for the best performance and will be set during the Alignment procedure (See Above).
  • TRANSIENTS - Short and sudden events in music such as a cymbal crash or the crack of a stick on a snare drum, all of which are difficult for a hi-fi to reproduce.


  • UPnP - (Universal Plug and Play) is a set of networking standards designed to ensure compatibility between computer devices and suitable audio/video components. As an example, UPnP server software loaded onto a home computer or network storage device will allow it to be accessed by streaming music and video players on the network around your house.
  • USB - (Universal Serial Bus) A type of data connection originally used on computers, but now commonly used with MP3 players and other hi-fi and home cinema products, superseded by USB 2.0, USB 3.0 and now in some cases, USB-C.


  • VALVE - Also known as “Tubes” in the USA. Electrical components used to amplify signals that use electrodes in a vacuum tube, now replaced by the Transistor in most applications. Felt by some enthusiasts to give a warm, seductive sound with great tonality that transistors lack.
  • VTA - (Vertical Tracking Angle), applies to the angle of the Stylus Cantilever relative to the record playing surface, generally adjusted by raising/lowering the turntable arm height and set during the Alignment procedure. (See Above.)


  • WATT - More Watts can equal more output, but the levels achievable depend on speaker sensitivity and room size.
  • WIDESCREEN - The 16:9 (1.78:1) screen shape used on most modern TVs and DVDs. Many cinema films are made in an even-wider 21:9 (2.35:1) shape, so your picture will still have black bars top and bottom on a widescreen TV.
  • WI-FI - Commonly accepted term for the IEEE802.11 standard that wirelessly connects data and AV devices and commonly found on laptops and tablet computers. Available in various versions such as Wireless b, g and n, in ascending order of speed. The standard requires that faster versions should be backwardly compatible with the slower ones, but bear in mind that using a wireless “b” device on a wireless “n” network for example will slow everything down to the lower speed.
  • WMA - (Windows Media Audio) is Microsoft's rival to MP3 which is claimed to offer similar sound with more effective audio compression.