Neumann KH 80 DSP 160×600
DynPEQ 160×400

Welcome to our Glossary of Tech Terms! We’ll define those terms and acronyms that ay be unfamiliar to you, enabling you to get the most out of our Resource Library. Our Editors and Contributors will continue to add definitions you’ll hopefully find to be helpful, so check back.

A-weighted

In equipment that tests sound pressure levels, employing a curve that allows the device to measure sound in a way that is similar to how we hear at moderate sound pressure levels. (See also c-weighted).

 

Active Monitor

Monitor speaker that has an amplifier and power supply (and possibly other electronics) built into it.

 

AES/EBU

Short for Audio Engineering Society/European Broadcast Union. Typically using balanced XLR connectors, this format transfers digital audio (two channels) with timing data and sample rate information. Mostly found on pro-level devices. AES/EBU is not subject to SCMS.

 

Attenuation

A signal loss, a lowering of level, as in attenuating the loudness of one audio component. Opposites: Amplification, boost.

 

A/D converter

A device that converts analog signals into digital signals, via a process usually called sampling. The opposite of a D/A converter.

 

ADR

Short for Automated Dialog Replacement, the overdubbing of audio for film or video work, required when the original location sound is inadequate or unusable.

 

Amplification

The strengthening of an audio signal for an increase in loudness. Opposite: Attenuation.

 

Automation

A feature in DAWs (digital work stations) and on some consoles that allows changes in a mix to be drawn in or recorded, and played back in real-time.

 

Acoustic Treatment

Materials, electronic devices, and specially designed Fixtures that change they way sound dissipates in a room. Since few rooms are built for acoustic quality, most rooms will accent or diminish certain frequencies based on a room’s dimensions, building materials, and surface finishes. Acoustic treatment helps to rectify anomalies that would prevent successful mixes.

 

ADSR

Short for Attack, Decay, Sustain, and Release, one way of defining the stages a sound wave goes through as it moves through the air. In reference to synthesizers, these are changeable parameters that allow the user to modify the envelope of a sound.

 

ASIO

Short for Audio Stream Input/Output, a driver protocol developed by Steinberg that allows a software application to have direct access to a computer’s sound card.

Baffle

Any construction or device which reduces the strength of a sound wave as it travels through the air. Baffles help control the way sound reacts in a space. Speaker cabinets use baffles to absorb sound pressure and control cabinet resonance. Baffle is sometimes used interchangeably with Gobo.

 

Balanced (Audio Term)

A method of connecting audio devices using impedance-matched inputs and outputs, reducing the chance of noise entering the signal path.

 

Bandwidth

A span of audio frequencies or a measure of data throughput capacity. The audio bandwidth of the human ear is generally accepted as 20 Hz – 20,000 Hz. In computing (usually referring to networking), bandwidth refers to an amount of data transfer that a system can handle (measured in bits per second).

 

Bantam Connector

A type of connector often used in patchbays and other applications, favored for its space-saving dimensions (4.4 mm (0.173″). Also known as TT/tiny telephone.

 

Bass Trap

A low-frequency sound absorber, used to minimize undesirable room resonances.

 

Bi-Directional

A type of microphone polar pattern where the mic is most sensitive directly in front of and directly behind the capsule. It has maximum rejection at the sides of the mic. Also called “figure-8,” the bi-directional polar pattern is typical of ribbon microphones, but is found in some condenser microphones also.

 

Bit Rate

In digital audio, the bit rate is equal to the sampling frequency multiplied by the number of bits per sample for each channel. 1.41 Mbit/s is the data bit rate for a CD. The highest bit rate for an mp3 is 320kbit/s. Also known as bit depth.

 

Bleed (Audio Term)

Sound transfer, usually undesirable and often hard to control, as in sound from one instrument being picked up by a microphone dedicated to another instrument, or signals from one tape track appearing on adjacent tracks, or sound escaping from a supposedly soundproofed environment.

C weighted

In equipment that tests sound pressure levels, employing a curve that is basically flat with a 3 dB drop at 31.5 Hz and a 3 dB roll-off starting at 8 kHz. It is designed to mimic the way we process sound at higher sound pressure levels. (See also a-weighted).

 

Cannon Connector

See XLR.

 

Cardioid

A microphone polar pattern in which the highest sensitivity is at the front, becoming less sensitive on the sides, and rejecting sound coming from the rear of the mic.

 

Coaxial

Any cable that consists of an outer conducting metal shield that is insulated from a central conducting core.

 

Codec

Short for coder-decoder or compression-decompression – a device or program that compresses digital data into a different (usually smaller) format than the original and is then capable of decompressing and “re-translating” the information.

 

Compression (Audio Term)

In reference to sound waves, the first half of a sound wave that creates a high pressure area due to its movement through the air.

 

Compressor

In audio, a device that enables automated control of dynamics (loudness control).(See also limiter)

 

Control Change Messages

A MIDI protocol that can send a range of values (0-127) that can modify parameters in MIDI equipment. 0-31 are continuous controllers that you can imagine as MIDI “knobs.” 64-95 are on/off controllers that you can imagine as “switches.” Some of these messages have predefined uses. Others are undefined and many synthesizers, samplers, and MIDI software programs allow you to assign your own parameters to the MIDI messages. Common MIDI controllers are: #1 modulation wheel, #7 volume, #10 pan, and #64 sustain pedal.

D/A Converter

A device that converts digital audio data into analog voltages (usually for playback). The opposite of an A/D converter. (See also Sampling).

 

DAT

DAT (short for Digital Audio Tape) [TAB] DAT is linear magnetic tape format for digital audio, much in use during the late ‘80s and early ‘90s, employing the same rotary head technology as VCRs (Video Cassette Recorders—remember those?). DAT can record at lower (32 kHz), equal (44.1 kHz) or higher (48 kHz) sample rates than a CD.

For fear of piracy from CDs and other digital audio sources, legislation was enacted, at the behest of the RIAA (Recording Industry Association of America) in 1992 as part of the Audio Home Recording Act that required DAT recorders equipped with S/PDIF inputs to have Serial Copy Management System (SCMS) implemented, a feature to prevent digital copying of 44.1 kHz audio files for more than a single generation.

 

Decay

In reference to sound waves, the portion of a sound wave in which its amplitude decreases until it is inaudible. In envelopes like ADSR the D stands for decay, the timing parameter that controls how quickly a signal is attenuated after the first Attack peak.

 

Decca Tree

A stereo miking technique in which at least three omni-directional microphones are used, with two mics placed around six feet apart, and the third halfway between the two mics but about 5 feet closer to the sound source. Picture an upside-down “T.” This technique is commonly used for orchestras and film recording.

 

Delay (Audio Term)

A reiteration of sound that is heard as a separate event from the original sound (as in an echo).

 

Dither

During bit-depth reduction, e.g. from 24 to 16 bits, quantization errors can introduce unwanted distortion. The process of dither can counteract that distortion. A low-level noise source is introduced, and the noise (called dither, typically white noise that has had filtering applied, often called noise-shaping) prevents the squaring-off of waveforms around the least significant bit, thus keeping the signal just above the threshold of the least significant bit. This results in smoother sound at the reduced resolution (lower bit rate).

Dithering is programmed into devices and software programs, and different programmers do it differently, so choosing one device or program over another to do your bit-depth reduction can produce greatly differing results – trial and error is often recommended.

 

DVD-Audio

A high-resolution digital audio format using DVD discs to store the audio data. DVD-A can run 74 minutes of either two channels of 192 kHz/24-bit or six channels of 96 kHz/24-bit. Due to the storage capacity, there is no need for lossy compression formats. At the high end of digital audio, DVD-A competes wth SACD.

 

Dynamic Microphone

A microphone that uses a diaphragm connected to a coiled wire where the coiled wire is suspended in a magnetic field. When sound waves hit the diaphragm, the coil moves, creating an electrical current due to its movement in the magnetic field.

 

Dynamic Range

The difference, measured in decibels, between the softest and loudest parts of an audio event.

Edit Decision List (abbr. EDL)

A way to make changes to audio files in a DAW, where the original audio files are not changed. Instead, the DAW makes notations of the cuts and edits made. This notation is the edit decision list. The DAW uses the edit decision list to know what parts of the original audio file to play, when to play them, and how to play them.

 

Editing (Audio Term)

In audio, editing is the art, science, and magic of re-arranging and correcting all or parts of a recording.

 

Envelope

In reference to audio (e.g. as programmable on synthesizers), a description of the timings and level changes of a sound event, from beginning to end. (See also ADSR).

 

Equalization

The act of changing the tonal characteristics of a sound, by raising/boosting or attenuating/cutting specific frequency bands.

Fader

A manual control commonly used on mixing consoles and graphic equalizers. A variable, attenuating potentiometer that slides up and down (as opposed to working with circular motion like control knobs or jog wheels do).

 

Feedback

An output signal returning to its own input, either acoustically (e.g. a mic signal coming out of speakers and being picked up again by the same mic), or electronically. In digital delays, the feedback parameter (also called regeneration) controls the repeats (echo).

 

Figure-eight

See “bi-directional”.

 

Finalize (Audio Term)

The final step in creating a CD, “closing” the disc so it can be played in most standard CD players. During this process, the TOC (or Table of Contents) is included on the CD.

 

FireWire

See IEEE 1394

 

Fletcher-Munson Hearing Curves

Fletcher and Munson were researchers in the ’30s who published findings about the way the human ear reacts to sound. Their findings showed that at lower sound levels humans are most sensitive to mid-range frequencies and less sensitive to low- and high-range frequencies. As a sound’s amplitude increases, the ear’s response tends to even out across the audio spectrum.

 

Foley

The creating of sound effects, usually for film and video. Many times the items used to create sound effects are not what you would expect. Think about the opening scene of Monty Python And The Holy Grail, where coconuts provide the sound of horse hooves…

 

Frequency Response

How an audio device reacts to frequencies across the audio spectrum; usually depicted in a frequency response chart, a graph that displays how the device reacts to specific frequency bands at specific amplitudes. Be sure to know the resolution of the graph and if smoothing has been applied, and realize that (especially in the case of microphones and speakers) your ears may tell a different story from the graphs.

 

Full Scale (abbr. FS)

In digital audio the absolute highest permissible audio level. Exceeding it causes severe clipping, a nasty kind of distortion. Instances where the signal goes into digital clipping are called overs.

 

Fundamental (Audio Term)

The root frequency of a sound wave, the first harmonic in the overtone series.

Gaffer Tape

A more expensive but far superior alternative to the better-known duct tape, it won’t leave residue after it is removed from a surface, can be torn by hand but is very resilient, and can be reused. Comes in many sizes and colors and finishes, not widely available but worth searching for. Referred to as “gaff” tape for short.

 

Gain (Audio Term)

How much an electronic circuit amplifies a signal, measured in decibels.

 

Generational Loss

The degradation in quality of the audio signal when transferring audio from one analog tape to another analog tape.

 

Gobo

Short for go-between, this can be any type of barrier that is placed between instruments or microphones to help control bleed and other sonic issues. If you are recording in a very live room, you could place a gobo behind the mic to reduce the amount of room reflections that are being picked up by the mic. In a pinch, a gobo can be as simple as a couple chairs and a thick comforter.

 

Graphic Equalizer

An equalizer that uses sliding faders instead of rotating knobs, thus giving you a graphic representation of your settings.

 

Ground (Electrical Term)

An electrical path to the earth, as provided by the ground prong of a three-prong ac connector. Proper grounding of electrical equipment avoids undesirable hum and buzz noises, and it is important in preventing harm to gear or people.

 

GUI

Short for Graphic User Interface, what you see and work with on contemporary computer screens that lets you take control—icons, folders, windows etc.

IEEE 1394

(IEEE=Institute of Electrical and Electronics Engineers), an interface protocol to connect computer devices. There are two versions, one transmitting up to 400 Mb/s, the other up to 800 Mb/s. Apple’s trademarked term for the IEEE 1394 protocol is FireWire, Sony calls it iLink, Texas instruments calls it Lynx.

 

iLink

See IEEE 1394

 

Insert (Audio Term)

A send-and-return signal pathway that allows a signsl from an individual console track to be sent to and returned from an external device (typically an outboard effect processor), all on one single TRS connector.

 

Iso Booth

Short for isolation booth, any room or space that is acoustically sealed off from a main tracking area. Using an iso booth keeps louder instruments from bleeding too much into other mics in a room. Tossing a guitar cabinet into the front coat closet with a few extra blankets is one way to create an iso booth on the fly.

Kef America LS50 – 728×90

Jack (Audio Term)

The receptor part of a connector, the hole where the plug goes. (In Europe, jack is commonly used for just the 1/4” connector as opposed to RCA, XLR and other types).

Leakage

Sound transfer, usually undesirable and often hard to control, as in sound from one instrument being picked up by a microphone dedicated to another instrument, or signals from one tape track appearing on adjacent tracks, or sound escaping from a supposedly soundproofed environment.

 

Limiter

A type of compressor that controls the dynamics (loudness fluctuations) of signals.

 

Line Level

A type of level (strength) of electrical signal used in professional audio equipment. There are two versions—professional gear runs at +4 dBu (1.23 volts) and consumer line level is at -10 dBV (.316 volts). (The two most common other level types: mic level, speaker level.)

 

Lynx

See IEEE 1394.

Mastering (Audio Term)

According to renowned mastering engineer Bob Katz, mastering is the art of refining and polishing a mix to take it to the next quality level. Originally, mastering was the preparation of audio for the transfer from tape to vinyl. Nowadays, it can mean varying levels of processing at the end of the production chain, where recorded material is prepared for duplication and distribution.

 

Mic Level

A type of level (strength) of electrical signal used in professional audio equipment, a weak signal measured in mV (millivolts) generated by the microphone; about 60 dB lower than line level, it requires a pre-amplifier to bring it up to line level.

 

Mix (Audio Term)

The combination of tracks into a temporary or final sound file representing the totality of the project.

 

Motherboard

The main circuit board of a computer. It houses and connects all of the hardware necessary for computing. This includes the processor (CPU), the memory (RAM), and other peripherals (PCI cards, video cards, networking cards, etc).

 

Mp3

A file compression format that significantly reduces the size of an audio file. The full name is MPEG-1 Audio Layer 3, where mpeg stands for Moving Picture Experts Group. Mp3 files are much smaller than their CD versions—at 128 kbit/s (the most common compression) the ratio is roughly 1:10. It is a lossy compression, sound quality deteriorates with compression and cannot be regained.

Near Field Monitor

Monitor designed to have a sweet spot that is about 3-4 feet from the listener. (The term is in common usage but believed to be a trademark of Edward M. Long Associates of Oakland, CA.)

 

Noise (Audio Term)

Any type of undesirable sound that is recorded or reproduced live.

 

Nyquist Frequency

In digital audio, the highest frequency that can be accurately sampled—it can be no higher than at ½ of a chosen sample rate. Example: The CD sampling rate of 44.1 kHz allows accurate representation of frequencies up to around 21 kHz (hence here the Nyquist frequency) which is near the upper limit of human hearing.

OS

Operating system

 

Over (Audio Term)

A type of digital clipping that occurs when an input signal exceeds 0 dB Full Scale.

 

Overdub

To overdub is to record additional material after the “basics”, e.g. a singer being recorded (overdubbed) in isolation after the rhythm section has been tracked.

 

Overheads

Mics that are placed above a sound source, configured to create a stereo image. Commonly used with drums to record the cymbals and the entire kit from above; overheads can be used on small ensembles as well.

Parametric Equalizer

An equalizer that allows you to control the gain, target frequency, and “Q” (bandwidth) of a frequency band.

 

Passive Monitor

Monitor speaker requiring speaker-level signals from the power output stage of an external power amplifier to produce sound.

 

Patch (Audio Term)

When used as a verb, to patch means to route signal to/from an external device, usually with patchcords and possibly with a patchbay. In synthesizers, a patch is a configured sound that can be recalled for playback. In computer terms, a patch is a correction that fixes functionality problems in a software program.

 

Patch Bay

A device that consolidates signal routing between audio devices, made of rows of jacks in an “output over input” configuration (see picture).

 

Peak Hold

A meter setting that will display the highest signal on a peak meter, usually by leaving an LED lit up at the peak level. The length of time the peak remains indicated may be adjusted to the users preference.

 

Peak Program Meter

Abbr. PPM, a meter that is designed to respond to peak levels which is especially important in digital recording to avoid clipping.

 

Phantom Power

Typically a 48 volts DC current applied to pins 2 and 3 on an XLR mic cable connected to a condenser mic requiring phantom power to operate.

 

Phone Connector

See 1/4”

 

Phono Connector

See RCA connector.

 

Plug-in

Software that is designed to be used within another software program.

 

Producer’s Desk/Couch

Many consoles have, at one end, a surface without any audio controls, where traditionally a producer settles in, unless s/he prefers the producer’s couch in the back of the room. The one who sits here is the only one who can say “Make it so” without fear of contradiction….

RAID

Short for Redundant Array of Independent Disks, a technology that allows a computer to store data on multiple hard drives simultaneously. RAID level 1 lets users keep a real-time, backup copy of data in case one drive fails. In the event of drive failure, the computer simply uses the drive(s) that still work(s). There are different levels and functions of RAID, but RAID level 1 is the most useful for audio applications.

 

RCA connector

An unbalanced connector where the plug has one pin housed in a small, circular casing. The pin is hot and the surrounding case is the shield. Also known as a phono connector.

 

Region (Audio Term)

A function of a DAW that designates a section of an audio file for multiple purposes. Regions can be references for playlists or can be edited independent of the rest of audio file.

 

Resolution (Audio Term)

A numeric measurement defining the smallest detail, which in turn defines the level of accuracy of representation. In digital audio the resolution depends on Bit Rate, Sample Rate, Quantization and Compression. Other usages of the term: Clock fractions per quarter note in MIDI sequencers; number of available steps for MIDI controllers, typically 128 steps, except for Pitch Bend, not technically a CC Control Change message, with 14-bit resolution resulting in 16,384 values. In other fields: Pixel (picture elements) resolution in digital video and photography and print media.

 

RTAS

Short for Real Time Audio Suite, a software plug-in format designed by Digidesign. RTAS uses a host computer’s hardware for processing.

Neumann TLM107 728×90

S/PDIF

Short for Sony/Philips Digital Interchange Format. Typically using Phono/RCA connectors or optical cables (Toslink), this format transfers digital audio (stereo) with timing data, Mostly found on semi-pro and consumer devices where the SCMS protection may inhibit repeated copying of files via S/PDIF even if these files are the user’s own.

 

SACD

Short for Super Audio Compact Disc. SACD is a high-resolution consumer digital audio format that uses DSD (Direct Stream Digital) technology. DSD uses a 1-bit 2.8 MHz sampling rate for digital conversion. A hybrid SACD can store the hi-res stereo and 5.1 surround version of an album, as well as the standard 44.1 kHz/16-bit version (which any CD player can play). The SACD spec also makes room for images and video clips. At the high end of hi-res consumer digital audio, SACD competes wth DVD-A.

 

Sampling (Audio Term)

In digital audio, the process of taking regular measurements of an analog signal’s voltage, converting sound we can hear into data that computerized devices can handle and store. See also A/D converter and D/A converter.

 

Sampling Frequency

The number of times per second that a measurement of the analog audio signal’s voltage is taken by the A/D converter. (See picture.) The sampling rate standard for CD audio is 44.1 kHz. Higher sampling rates produce better sound quality (all else being equal).

 

Sampling Rate

The number of times per second that a measurement of the analog audio signal’s voltage is taken by the A/D converter. (See picture.) The sampling rate standard for CD audio is 44.1 kHz. Higher sampling rates produce better sound quality (all else being equal).

 

SCMS

SCMS (short for Serial Copy Management System) is a protection technology to prevent repeated copying of digital audio files of 44.1 kHz sample rate on S/PDIF inputs among consumer audio devices, allowing no more than a single copy.

 

Scrub (Audio Term)

The action of moving tape back and forth across a playback head, to find an exact spot in the audio. Scrubbing on a DAW’s computer screen is done similarly, with the mouse, moving back and forth through a portion of an audio waveform display—to find optimal locations for editing.

 

Scrubbing

The action of moving tape back and forth across a playback head, to find an exact spot in the audio. Scrubbing on a DAW’s computer screen is done similarly, with the mouse, moving back and forth through a portion of an audio waveform display—to find optimal locations for editing.

 

Send (Audio Term)

A type of output from a DAW or console that allows signal to be routed to external devices. Sends usually have returns which accept signal coming back from the external device (typically processors like reverbs etc.). In live sound, sends can be used for monitor mixes, alternative board mixes for other devices, and cue mixes (in theater sound).

 

Shield

A structure or arrangement of conducting material that protects equipment from electrostatic or magnetic interference. This is also found in cables surrounding the insulated conductors. In a cable, the shield will either be wrapped-foil or a braided conductor.

 

Soffit mounted monitors

Monitor speakers flush-mounted in a wall enclosure that is acoustically decoupled from the wall and control room. Typically found in larger studios.

 

Speaker Level

A type of signal level (strength) of electrical signal, used between the power output stage of an amplifier and the (passive) loudspeakers connected to the amp’s speaker terminals.

 

Stem (Audio Term)

A type of submix, the contents of which need to be specified in detail from project to project. Stems are often supplied as the basis for overdubs or for mixes.

 

Submix

A combination of a selection of tracks from within a project, e.g. just the lead and background vocals combined into a stereo submix. Submixes can serve as stems.

Talkback Mic/Button

A feature on consoles that allows the engineer to communicate to the musicians in the tracking room or on stage.

 

TDM

Short for Time Division Multiplexing, a software plug-in format designed by Digidesign. TDM uses proprietary hardware cards for processing.

 

Time Code

Digital information that is used for synchronization between media devices and media formats.

 

TOC

Short for Table Of Contents, the additional track on the innermost portion of a CD that contains information about the number of tracks, where the tracks are, and how long they are. This is written during the finalizing process.

 

Toslink

Short for Toshiba Link, Toslink is a connector standard for digital audio transfer. Employing fiber optic cables, Toslink connectors are used for S/PDIF optical, ADAT Lightpipe and digital audio transfer in consumer electronic devices.

 

Track (Audio Term)

On analog tape, a track is the line of magnetization caused by a single record head as the tape passes over the head during recording and is read by the playback head during playback. In digital audio, this metaphor is continued in the GUI, although a track is no longer a strictly linear entity.

 

Tracking (Audio Term)

The action of recording (basics as well as overdubs), as opposed to editing, mixing, or mastering.

 

TRS connector

See 1/4”

 

TS connector

See 1/4”

 

TT connector

Tiny Telephone. See Bantam.

USB

Short for Universal Serial Bus, an interface protocol to connect computer devices. There are two versions, USB 1.0 (or 1.1) transmitting about 12 Mbps (megabits per second), and USB 2.0 transmitting up to 480 Mbps.

Virtual Instrument

The sounds of an instrument playable from a computer, sounds that were not recorded (not digitally sampled), but instead are being simulated by a computer program using your computer’s hardware to generate audio signals. Many virtual instruments respond to MIDI messages and DAWs use virtual instruments as plug-ins.

 

VST

Short for Virtual Studio Technology, an interface first introduced by Steinberg (now part of Yamaha) that allows synthesizers, plug-ins, and DAWs to work together.

 

VU Meter

Short for volume unit meter, a meter that is designed to respond to sound in the same way our ears do. Instead of measuring peaks and transients, the VU meter has slower response that shows average levels. It is referenced to +4 dBu at 0 VU and has specific needle ballistics that are set by ANSI (American National Standards Institute).

XLR

A type of connector used for analog or digital signal carriers, most commonly found on microphones and on pro-level equipment. Typically has 3 pins and is housed in a circular casing. Pin 1 is the ground/shield, pin 2 is hot and pin 3 is cold (but this could vary depending on the country you are in). Also known as a Cannon connector.

1/4” connector

A connector that transmits signal through its tip and provides ground/shield through its sleeve. A guitar cable uses this type of connector. Comes as unbalanced tip-ring (TS) or balanced tip-ring-sleeve (TRS) configuration. The TRS has multiple uses—it can transmit stereo signal (T = left, R = right, S = shield/ground), balanced signal (+ and– tied to the T and R, with S as the shield), or it can be used as an insert cable (T = send, R = return, S = ground/shield). The 1/4” connector is sometimes called Phone connector or Phone plug (not to be confused with Phono/RCA).

 

10 dB rule

When using multiple mics in close proximity to one another, differences in a sound wave’s time of arrival can cause phasing problems. If the sound of one instrument is going into multiple microphones, then make sure that there is (at least) a 10 dB signal difference between them to avoid phasing issues. (See also 3:1 rule).

 

3:1 rule/4:1 rule

When recording with multiple mics in close proximity, you can avoid phase problems by separating the mics by at least 3 times the mic-to-source distance. (see picture) For instance, if a mic is one foot away from its sound source, then no other mic should be closer than three feet from this first mic. (See also 10 dB rule.)

Kef America 55 Years of British Engineering – 728×90