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A patch cable, patch cord or patch lead is an electrical or
optical cable A fiber-optic cable, also known as an optical-fiber cable, is an assembly similar to an electrical cable, but containing one or more optical fibers that are used to carry light. The optical fiber elements are typically individually coated with ...
used to connect ("patch in") one electronic or optical device to another for signal routing. Devices of different types (e.g., a switch connected to a computer, or a switch to a router) are connected with patch cords. Patch cords are usually produced in many different colors so as to be easily distinguishable from each other. Types of patch cords include
microphone A microphone, colloquially called a mic or mike (), is a transducer that converts sound into an electrical signal. Microphones are used in many applications such as telephones, hearing aids, public address systems for concert halls and publ ...
cables, fiber optic
spectroscopy Spectroscopy is the field of study that measures and interprets the electromagnetic spectra that result from the interaction between electromagnetic radiation and matter as a function of the wavelength or frequency of the radiation. Matter ...
cables,
headphone Headphones are a pair of small loudspeaker drivers worn on or around the head over a user's ears. They are electroacoustic transducers, which convert an electrical signal to a corresponding sound. Headphones let a single user listen to an a ...
extension cables, XLR connector, Tiny Telephone (TT) connector,
RCA connector The RCA connector is a type of electrical connector commonly used to carry audio and video signals. The name ''RCA'' derives from the company Radio Corporation of America, which introduced the design in the 1930s. The connectors male plug a ...
and ¼" TRS phone connector cables (as well as
modular Broadly speaking, modularity is the degree to which a system's components may be separated and recombined, often with the benefit of flexibility and variety in use. The concept of modularity is used primarily to reduce complexity by breaking a s ...
Ethernet Ethernet () is a family of wired computer networking technologies commonly used in local area networks (LAN), metropolitan area networks (MAN) and wide area networks (WAN). It was commercially introduced in 1980 and first standardized in 1 ...
cables), and thicker, hose-like cords ( snake cable) used to carry
video Video is an electronic medium for the recording, copying, playback, broadcasting, and display of moving visual media. Video was first developed for mechanical television systems, which were quickly replaced by cathode-ray tube (CRT) sy ...
or amplified signals. However, patch cords typically refer only to short cords used with patch panels. The term "patch" came from early use in telephony and radio studios, where extra equipment kept on standby could be temporarily substituted for failed devices. This reconnection was done via patch cords and patch panels, like the jack fields of cord-type telephone switchboards. Furthermore, patching could also create temporary atypical connections between devices for unusual needs. Analog music synthesizers typically use patch cables to interconnect functional sections, such as oscillators, filters, etc.


Construction

A patch cord cable differs from a standard structured cabling in that a patch cable is stranded for flexibility, whereas a standard cable is solid copper. Because the patch cord is stranded copper construction the
attenuation In physics, attenuation (in some contexts, extinction) is the gradual loss of flux intensity through a medium. For instance, dark glasses attenuate sunlight, lead attenuates X-rays, and water and air attenuate both light and sound at var ...
(signal loss) is higher on patch cords than solid cable so short lengths should be adhered to. They can be as short as , to connect stacked components or route signals through a
patch bay A patch panel is a device or unit featuring a number of jacks, usually of the same or similar type, for the use of connecting and routing circuits for monitoring, interconnecting, and testing circuits in a convenient, flexible manner. Patch ...
, or between for snake cables. As length increases, the cables are thicker or more shielded, or both, to prevent signal loss (
attenuation In physics, attenuation (in some contexts, extinction) is the gradual loss of flux intensity through a medium. For instance, dark glasses attenuate sunlight, lead attenuates X-rays, and water and air attenuate both light and sound at var ...
) and the introduction of unwanted radio frequencies and hum (
electromagnetic interference Electromagnetic interference (EMI), also called radio-frequency interference (RFI) when in the radio frequency spectrum, is a disturbance generated by an external source that affects an electrical circuit by electromagnetic induction, electrost ...
). Patch cords are often made of
coaxial cable Coaxial cable, or coax (pronounced ) is a type of electrical cable consisting of an inner conductor surrounded by a concentric conducting shield, with the two separated by a dielectric ( insulating material); many coaxial cables also have a p ...
s, with the signal carried through a shielded core, and the
electrical ground In electrical engineering, ground or earth is a reference point in an electrical circuit from which voltages are measured, a common return path for electric current, or a direct physical connection to the Earth. Electrical circuits may be co ...
or earthed return connection carried through a wire mesh surrounding the core. Each end of the cable is attached to a connector so that the cord may be plugged in. Connector types may vary widely, particularly with adapting cables. Patch cords may be: * single- conductor wires using, for example, banana connectors (or pin plugs) *
coaxial cable Coaxial cable, or coax (pronounced ) is a type of electrical cable consisting of an inner conductor surrounded by a concentric conducting shield, with the two separated by a dielectric ( insulating material); many coaxial cables also have a p ...
s using, for example, BNC connectors * shielded or unshielded Cat5, Cat5e, Cat6 or Cat6A cables using
8P8C A modular connector is a type of electrical connector for cords and cables of electronic devices and appliances, such as in computer networking, telecommunication equipment, and audio headsets. Modular connectors were originally developed fo ...
(RJ-45) modular connectors with straight-through T568A or T568B wiring (modular cables wired to T568A at one end and T568B on the other are more commonly referred to as crossover cables) * qualified
optical fiber An optical fiber, or optical fibre in Commonwealth English, is a flexible, transparent fiber made by drawing glass ( silica) or plastic to a diameter slightly thicker than that of a human hair Hair is a protein filament that grows ...
cables for use with modular fiber optic spectroscopy equipment A patch cord is always fitted with connectors at both ends. A pigtail is similar to a patch cord and is the informal name given to a cable fitted with a connector at one end and bare wires (or bare fibre) at the other. In the context of copper cabling, these cables are sometimes referred to as blunt patch cords and the non-connectorized end ("the pigtail") is intended to be permanently attached to a component or terminal. Optical fiber pigtails, in contrast to copper pigtails, can be more accurately described as a connector than a cable or cord. A fiber pigtail is a single, short, usually tight-buffered, optical fiber that has an optical connector pre-installed on one end and a length of exposed fiber at the other end. The end of the fiber pigtail is stripped and fusion spliced to a single fiber of a multi-fiber trunk. Splicing of pigtails to each fiber in the trunk "breaks out" the multi-fiber cable into its component fibers for connection to the end equipment.


Music and sound recording

A variety of cables are used to carry electrical signals in sound recording studios and with electronic or electrical musical instruments. Microphones are typically connected to mixing boards or PA systems with XLR
microphone A microphone, colloquially called a mic or mike (), is a transducer that converts sound into an electrical signal. Microphones are used in many applications such as telephones, hearing aids, public address systems for concert halls and publ ...
cables which use three-pin XLR connectors. A huge range of electric or electronic instruments use 1/4 inch mono patch cords to connect the instrument to the amplifier, such as the
electric guitar An electric guitar is a guitar that requires external amplification in order to be heard at typical performance volumes, unlike a standard acoustic guitar (however combinations of the two - a semi-acoustic guitar and an electric acoustic gu ...
, electric bass,
synthesizer A synthesizer (also spelled synthesiser) is an electronic musical instrument that generates audio signals. Synthesizers typically create sounds by generating waveforms through methods including subtractive synthesis, additive synthesis a ...
, electric piano, or electronic drum machine. Musicians playing electric or electronic instruments often use longer cables (from 10 to 20 feet) between their instrument and their amplifier, and then use shorter patch cords (from a few inches to one or two feet long) to connect chains of effects devices, "
stomp box A stomp box (or stompbox) is a percussion instrument consisting of a small box placed under the foot, which is tapped or stamped on rhythmically to produce a sound similar to that of a bass drum. A stomp box allows a performer such as a sing ...
" pedals, or other signal processors. DJs using record players connect their turntables to mixers or PA systems with stereo
RCA connector The RCA connector is a type of electrical connector commonly used to carry audio and video signals. The name ''RCA'' derives from the company Radio Corporation of America, which introduced the design in the 1930s. The connectors male plug a ...
s. DJs sometimes have to use equipment with multiple cable types, which can create connection difficulties; for example, the DJ's record players and DJ mixers all use RCA connectors, but if they use a drum machine or a bass synthesizer, it may have a 1/4 inch mono connector. To resolve this problem, DJs can either use adapters or special cables (e.g., RCA to 1/4 inch mono). Heavier-gauge cables are used for carrying amplified signals from
amplifier An amplifier, electronic amplifier or (informally) amp is an electronic device that can increase the magnitude of a signal (a time-varying voltage or current). It may increase the power significantly, or its main effect may be to boost t ...
s to speakers (both in a PA system and with instrument amplifiers). ¼" TRS phone connector cables can carry stereo signals, so they are used for stereo headphones and for some patching purposes (e.g., inserting an effect into an insert connection in a mixer). Music venues, concert halls, and recording studios also use a thicker, hose-like cord called a snake cable (or a "snake"), which consists of a bundle of many individual cables with
patch bay A patch panel is a device or unit featuring a number of jacks, usually of the same or similar type, for the use of connecting and routing circuits for monitoring, interconnecting, and testing circuits in a convenient, flexible manner. Patch ...
s at either end so that audio gear can be connected. The patch bay is a flat panel of audio connectors where XLR cables (often both "male" and "female") and 1/4 inch jacks can be plugged in. The "snake" cable makes setup more convenient, because if a sound engineer did not have a "snake", she or he would have to run 20 or 30 individual microphone and instrument cables from the stage to the mixing booth. The cables could get tangled or mixed up, and it would be hard to know, when faced with 20 connectors at the end of the cable run, which cable was associated with which microphone or instrument. The patch bay is numbered, so that the engineer can note which microphone or instrument is plugged into each numbered connection. Patch cables can also be used on
video synthesizer A video synthesizer is a device that electronically creates a video signal. A video synthesizer is able to generate a variety of visual material without camera input through the use of internal video pattern generators. It can also accept and ...
s.


See also

* Cable management *
Crossover cable A crossover cable connects two devices of the same type, for example DTE-DTE or DCE-DCE, usually connected asymmetrically (DTE-DCE), by a modified cable called a crosslink. Such a distinction between devices was introduced by IBM. The cros ...


References


External links


White Papers - Cable Anatomy (microphone, speaker, and instrument)
Telephony equipment Networking hardware