Multicore cable
Encyclopedia
An audio multicore cable (often colloquially referred to in America as a snake cable or just a snake) is a cable which contains from 4 to 64 individual audio cables inside a common outer jacket. Audio multicore cable
Multicore cable
An audio multicore cable is a cable which contains from 4 to 64 individual audio cables inside a common outer jacket. Audio multicore cables are widely used whenever multiple audio signals, for example from a number of microphones, need to be conveyed between common locations...

s are widely used whenever multiple audio signals, for example from a number of microphone
Microphone
A microphone is an acoustic-to-electric transducer or sensor that converts sound into an electrical signal. In 1877, Emile Berliner invented the first microphone used as a telephone voice transmitter...

s, need to be conveyed between common locations. Typical professional audio
Professional audio
Professional audio, also 'pro audio', refers to both an activity and a type of audio equipment. Typically it encompasses the production or reproduction of sound for an audience, by individuals who do such work as an occupation like live event support, using sound reinforcement systems designed for...

 applications include audio recording, sound reinforcement, and broadcasting
Broadcasting
Broadcasting is the distribution of audio and video content to a dispersed audience via any audio visual medium. Receiving parties may include the general public or a relatively large subset of thereof...

.

The term can be used to refer to the basic cable as may be obtained from a supplier, or a cable with the ends terminated in either a multipin connector, a number of separate connectors on the individual pairs, or a box or panel with a number of chassis-mounted connectors. Different termination methods can be used on each end to suit the application. When individual connectors are used, three pin XLR connector
XLR connector
The XLR connector is a style of electrical connector, primarily found on professional audio, video, and stage lighting equipment. The connectors are circular in design and have between 3 and 7 pins...

s are most common, although 1/4" jack connectors are also occasionally used.

Assembled audio multicore cables are found in both portable applications, where they are stored loose or on a cable drum, or are permanently installed in a building.

Core conductors

The vast majority of audio multicore cables consist of a number of twisted-pair copper wires, suitable for balanced audio
Balanced audio
Balanced audio is a method of interconnecting audio equipment using impedance-balanced lines. This type of connection is very important in sound recording and production because it allows for the use of long cables while reducing susceptibility to external noise.Balanced connections use...

. However, the broadcast industry tends to use audio multicores containing starquad cables, due to their increased rejection of radio-frequency interference. Some multicore cables designed for unbalanced audio are made, and they contain a number of single-core screened cables.

Core screening

The individual cables inside the multicore are usually individually screened. This reduces crosstalk between cables and also enables each cable to have a screen or ground that is isolated from other cables, significantly reducing the possibility of earth loops.

A foil-screen is typically used, comprising thin aluminium wrapped around the conductors. An uninsulated drain wire is contained inside the screen to facilitate ground connection. A less common construction is a lapped or braided screen compromising thin wires wrapped around the conductors. This is felt to give improved flexibility but less effective screening.

Core insulation

This describes the method used to isolate the screening between individual cores; two approaches are common. The first method has an extruded plastic sheath around each individual core, making the multicore appear like a number of individual audio cables bundled together inside an outer sheath. The second method dispenses with the individual sheath and typically wraps the screening with very thin plastic; in some cases this plastic is bonded to the foil sheath.

The individually-sheathed construction has the advantage that individually cores can easily be terminated to individual connectors at the ends of the cable. Its disadvantage is that the size and weight of the cable are increased. When a cable without individual sheaths has to be terminated to multiple connectors, it is common practice to create individual sheaths using heat-shrinkable tubing.

Overall screen

A small number of multicore cables compromise twisted-pairs with an overall screen. These are virtually obsolete and typically only found in older broadcast installations, the use of individual screens is now virtually standard.

Some multicore cables do contain an overall braid screen in addition to the individual screens on each core. This also increases the mechanical durability of the cable.

Core identification

Different cable manufacturers use different methods of identification for the shielded pairs of cable. Belden
Belden Inc.
Belden Inc.Belden Inc. designs, manufactures, and markets highly engineered signal transmission products for demanding applications. These cable, connectivity and networking products serve the industrial automation, enterprise, security, transportation, infrastructure, residential and consumer...

 have a sequenced color code and a number for each of the conductors in their products of up to 52 pair cables, for their plenum cables each pair is covered with their patended Belfoil shield, that is only conductive on the inner surface. For their portable cables they use a French braid
French braid
A French braid, or French plait, is a type of braided hairstyle.-Description:Unlike the simplest form of three-strand braid, in which all of the hair is initially divided into three sections which are simultaneously gathered together near the scalp , a French braid starts with three small sections...

. Canare, Mogami, and GEPCO mark numbers on the PVC
PVC
Polyvinyl chloride is a plastic.PVC may also refer to:*Param Vir Chakra, India's highest military honor*Peripheral venous catheter, a small, flexible tube placed into a peripheral vein in order to administer medication or fluids...

 insulation
Electrical insulation
thumb|250px|[[Coaxial Cable]] with dielectric insulator supporting a central coreThis article refers to electrical insulation. For insulation of heat, see Thermal insulation...

 of the individual pairs.

Composite multicores

Composite multicores combine different types of signals in the one cable. They may contain coaxial
Coaxial
In geometry, coaxial means that two or more forms share a common axis; it is the three-dimensional linear analogue of concentric.Coaxial cable, as a common example, has a wire conductor in the centre a circumferential outer conductor and an insulating medium called the dielectric separating...

 cores for video
Video
Video is the technology of electronically capturing, recording, processing, storing, transmitting, and reconstructing a sequence of still images representing scenes in motion.- History :...

 , twisted pair
Twisted pair
Twisted pair cabling is a type of wiring in which two conductors are twisted together for the purposes of canceling out electromagnetic interference from external sources; for instance, electromagnetic radiation from unshielded twisted pair cables, and crosstalk between neighboring pairs...

 for data or low voltage
Voltage
Voltage, otherwise known as electrical potential difference or electric tension is the difference in electric potential between two points — or the difference in electric potential energy per unit charge between two points...

 cores for mains power. Composite multicores are usually used to connect professional video camera
Professional video camera
A professional video camera is a high-end device for creating electronic moving images...

s, but they are now gaining usage in live event support with the introduction of the Yamaha PM1D which uses a composite cable to connect it to the stage box.

Analog multicore

The multicore cable runs from the stage box
Stage box
A stage box is a rugged metal housing used in the audio engineering and entertainment fields to connect microphones and other sound equipment to the multicore cable. It functions as an extension of the equipment cables, allowing for the sound desk to be situated further away from the stage, and...

 or microphone splitter
Microphone splitter
A microphone splitter has an input from a microphone and provides multiple output. Also known as a rathouse due to the large amount of cabling involved. A splitter is often used at larger venues to provide feeds from microphones or other sources to both a front of house mixing desk and a monitor desk...

 and then to the front-of-house
Front of House
Front of house is primarily a theatrical term, referring to the portion of the building that is open to the public. In theatre and live music venues, it typically refers to the auditorium and foyer, as opposed to the stage and backstage areas...

 sound desk or mixing console
Mixing console
In professional audio, a mixing console, or audio mixer, also called a sound board, mixing desk, or mixer is an electronic device for combining , routing, and changing the level, timbre and/or dynamics of audio signals. A mixer can mix analog or digital signals, depending on the type of mixer...

. Permanent installations have stage boxes mounted in the floor or side of stage and the plenum
Plenum cable
Plenum cable is cable that is laid in the plenum spaces of buildings. The plenum is the space that can facilitate air circulation for heating and air conditioning systems, by providing pathways for either heated/conditioned or return airflows...

 cable runs through the ceiling
Ceiling
A ceiling is an overhead interior surface that covers the upper limit of a room. It is generally not a structural element, but a finished surface concealing the underside of the floor or roof structure above....

 or false floor to the console, located either in the auditorium or the bio-box.

For temporary shows the stage box is placed at the side or rear of the stage and generally 75% of the connectors are female XLR
XLR connector
The XLR connector is a style of electrical connector, primarily found on professional audio, video, and stage lighting equipment. The connectors are circular in design and have between 3 and 7 pins...

 with the balance male XLR. The male XLR are used as returns to the stage for foldback
Foldback (sound engineering)
Foldback is the use of rear-facing heavy-duty loudspeakers known as monitor speaker cabinets on stage during live music performances. The sound is amplified with power amplifiers or a public address system and the speakers are aimed at the on-stage performers rather than the audience...

 (on-stage monitoring) or FOH at line level. Larger multicores have male and female connectors for each channel at the stage box end giving it more flexibility. In this system the male XLRs may be used to give a split to the foldback
Foldback
Foldback may refer to:*Foldback , a current-limiting device in power amplifiers*Foldback , a speaker used to direct sound to performers...

 desk. The foldback desk is connected by a cable with tails at both ends. The console end always has the opposite sex XLR connector. Larger shows tend to use a system with subsnakes which plug into the main stage box so one can use shorter mic leads on stage and have less clutter
Clutter
Clutter may refer to any of the following:*Excessive physical disorder** Clutter , a confusing or disorderly state or collection, and possible symptom of compulsive hoarding** A type of light pollution...

.

Balanced lines

The output of most microphones is balanced
Balanced line
In telecommunications and professional audio, a balanced line or balanced signal pair is a transmission line consisting of two conductors of the same type, each of which have equal impedances along their lengths and equal impedances to ground and to other circuits. The chief advantage of the...

 to reduce the pickup of electrical noise, and therefore requires two signal wires and an earth per channel. This necessitates the use of three-pin connectors. To reduce noise, the shields of each channel should be isolated from the other channels. If "phone jacks" are used instead of XLRs, TRS connector
TRS connector
A TRS connector is a common family of connector typically used for analog signals including audio. It is cylindrical in shape, typically with three contacts, although sometimes with two or four . It is also called an audio jack, phone jack, phone plug, and jack plug...

s should be used so that balanced signals can be maintained. A TRS connector plugged into a TS socket will ground the ring and maintain the positive signal integrity and work in a pseudo-balanced state. The use of TS connectors forces the system into an unbalanced state at all times and should be avoided.

Tails

The end of the multicore where the channels fanout is called the tail and it generally goes at the mixing desk end. Tails used for patching may have a mixture of male and female XLRs, or TRS connector
TRS connector
A TRS connector is a common family of connector typically used for analog signals including audio. It is cylindrical in shape, typically with three contacts, although sometimes with two or four . It is also called an audio jack, phone jack, phone plug, and jack plug...

s on each end.

Breakout cables

An audio multicore may also function as a breakout cable
Breakout cable
Breakout-style fiberoptic cable, often referred to as just "breakout cable", is basically several jacketed simplex fibers packaged individually inside one jacket. This differs from distribution style cable, in which several tight-buffered fibers are bundled together within the same jacket...

, if it has a compound connector on one end and component connectors on the other. This is more common in short multicores meant for in-studio
Studio
A studio is an artist's or worker's workroom, or the catchall term for an artist and his or her employees who work within that studio. This can be for the purpose of architecture, painting, pottery , sculpture, scrapbooking, photography, graphic design, filmmaking, animation, radio or television...

 connections, such as audio engines, analog to digital converters or digital mixing consoles. Multicore cables may also connect to either the front or back of patch panel
Patch panel
A patch panel or patch bay is a panel, typically rackmounted, that houses cable connections. One typically shorter patch cable will plug into the front side, whereas the back holds the connection of a much longer and more permanent cable...

s, when the patch panel is used as an access point or breakout box for connecting external inputs and outputs.

Multipin multicores

The ideal system uses multipins to connect the subsnakes to the main stage box (which may be rack mounted) and multipins to the main cores. This allows the system to be expanded by channel count or length. The multipin connectors are based on the MIL C5015 standard and are made by companies like Link in Italy
Italy
Italy , officially the Italian Republic languages]] under the European Charter for Regional or Minority Languages. In each of these, Italy's official name is as follows:;;;;;;;;), is a unitary parliamentary republic in South-Central Europe. To the north it borders France, Switzerland, Austria and...

 or Amphenol
Amphenol
Amphenol Corporation is a major producer of electronic and fiber optic connectors, cable and interconnect systems such as Coaxial cables. Amphenol is a portmanteau from the corporation's original name, American Phenolic Corp....

 in the United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...

. Alternative connectors like EDAC and Burndy are also used but lack the reliability of the alloy mil-spec style connectors. Examples include;
Multicore MIL C5015 Multipin Sends/Returns
8 core 25 pole 8/0
12 core 37 pole 8/4
16 core 54 pole 12/4
24 core 85 pole 20/4


While the sound reinforcement industry generally uses proprietary multicores depending on the application, the television
Television
Television is a telecommunication medium for transmitting and receiving moving images that can be monochrome or colored, with accompanying sound...

 industry has standardized on a 12-channel snake with a common 36-pin connector on each end known as DT-12. DT-12 snakes are commonly built into sports venues and run from where the TV truck is parked to areas such as the press box or playing field where audio is required by the TV production. The truck can then simply run a DT-12 patch snake between the truck and the house cabling, with actual XLR connectors then only being required at the very end of the snake in order to plug in microphones.

Snake cables can be replaced by using audio over Ethernet
Audio over Ethernet
In audio engineering and broadcast engineering, Audio over Ethernet is the use of an Ethernet-based network to distribute real-time digital audio....

, and similar multichannel digital audio
Digital audio
Digital audio is sound reproduction using pulse-code modulation and digital signals. Digital audio systems include analog-to-digital conversion , digital-to-analog conversion , digital storage, processing and transmission components...

 technologies such as AES10 (MADI).

Digital multicores

State of the art systems can now use digital multicore systems whereby the audio signal is encoded to digital using analog-to-digital converter
Analog-to-digital converter
An analog-to-digital converter is a device that converts a continuous quantity to a discrete time digital representation. An ADC may also provide an isolated measurement...

s, the channels are bundled together to be transported on a single wire to a destination then re-converted back to analog using D-to-As
Digital-to-analog converter
In electronics, a digital-to-analog converter is a device that converts a digital code to an analog signal . An analog-to-digital converter performs the reverse operation...

. Such systems are branded under names such CobraNet or EtherSound (respectively manufactured by Peak Technologies and Digigram) and licenced to many companies. Sometimes all that is run to the mix positions is control and all audio processing occurs in the Mix Box, or Stage Box.

The main problem with digital multicores is latency
Latency (audio)
Latency refers to a short period of delay between when an audio signal enters and when it emerges from a system...

, the time taken to encode into digital
Digital
A digital system is a data technology that uses discrete values. By contrast, non-digital systems use a continuous range of values to represent information...

 and then back into analog
Analog signal
An analog or analogue signal is any continuous signal for which the time varying feature of the signal is a representation of some other time varying quantity, i.e., analogous to another time varying signal. It differs from a digital signal in terms of small fluctuations in the signal which are...

 at the mixing console. Most stand alone digital consoles take their inputs in analog format and the cumulative latency is too great to go unnoticed. The second problem is cost, it is currently much more expensive to use a digital multicore for small systems. Most multicore systems use Ethernet
Ethernet
Ethernet is a family of computer networking technologies for local area networks commercially introduced in 1980. Standardized in IEEE 802.3, Ethernet has largely replaced competing wired LAN technologies....

 wiring as the physical medium, but the system must be as close to synchronous as possible and cannot share the same cable as data systems due to the risk of collisions.

CobraNet

The first viable Ethernet based audio multicore suffers from excessive latency and is only really being used for permanent installs. It is acceptable for the sound to the lobby to be delayed from the FOH
Front of House
Front of house is primarily a theatrical term, referring to the portion of the building that is open to the public. In theatre and live music venues, it typically refers to the auditorium and foyer, as opposed to the stage and backstage areas...

 as you cannot hear the direct sound from stage. CobraNet cards are available for Yamaha digital consoles.

EtherSound

The most recent Ethernet based system is rapidly gaining acceptance for live sound because of its low latency. Ethersound cards are available for Yamaha
Yamaha
Yamaha may refer to:* Yamaha Corporation, a Japanese company with a wide range of products and services** Yamaha Motor Company, a Japanese motorized vehicle-producing company...

 and Studer
Studer
Studer is a Swiss manufacturer of professional audio equipment, founded in Zurich in 1948 by Willi Studer. It is known primarily for the design and manufacture of analog tape recorders and mixing consoles. Studer also produce other technology solutions, such as telephony management systems and...

 digital consoles but the slots in Yamaha desks are limited to 16 inputs and outputs. When digital consoles come fitted with EtherSound, digital multicores will gain widespread acceptance.

Roland RSS Digital Snake

Roland Corporation
Roland Corporation
is a Japanese manufacturer of electronic musical instruments, electronic equipment and software. It was founded by Ikutaro Kakehashi in Osaka on April 18, 1972, with ¥33 million in capital. In 2005 Roland's headquarters relocated to Hamamatsu in Shizuoka Prefecture. Today it has factories in Japan,...

 RSS Digital Snake is a 40-channel digital audio transmission system using one standard CAT 5e cable. It features high quality remote controllable microphone preamps, configurable inputs and outputs and immunity to RF and electrical interference. A remote control unit allows users to easily adjust input gain and also features “scene” recall of preamp settings including level and phantom power status. The system offers built-in cable redundancy, automatically switching to a backup cable should the main cable be compromised. The system inputs can be “split” using approved Ethernet
Ethernet
Ethernet is a family of computer networking technologies for local area networks commercially introduced in 1980. Standardized in IEEE 802.3, Ethernet has largely replaced competing wired LAN technologies....

fast switching hubs providing for multiple “transformerless” audio feeds to monitor consoles, recording devices, and broadcast facilities.
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