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An audio multicore cable (often colloquially referred to as a multicore, snake cable or snake) is a thick cable which usually contains 4–64 individual audio cables inside a common, sturdy outer jacket. Audio
multicore cable
A multicore cable is a type of electrical cable that combines multiple signals or power feeds into a single jacketed cable. The term is normally only used in relation to a cable that has more cores than commonly encountered. Not all cables with mu ...
s are used to convey many
audio signal
An audio signal is a representation of sound, typically using either a changing level of electrical voltage for analog signals, or a series of binary numbers for digital signals. Audio signals have frequencies in the audio frequency range of r ...
s between two locations, such as in
audio recording
Sound recording and reproduction is the electrical, mechanical, electronic, or digital inscription and re-creation of sound waves, such as spoken voice, singing, instrumental music, or sound effects. The two main classes of sound recording te ...
,
sound reinforcement
A sound reinforcement system is the combination of microphones, signal processors, amplifiers, and loudspeakers in enclosures all controlled by a mixing console that makes live or pre-recorded sounds louder and may also distribute those sounds ...
,
PA system
A public address system (or PA system) is an electronic system comprising microphones, amplifiers, loudspeakers, and related equipment. It increases the apparent volume (loudness) of a human voice, musical instrument, or other acoustic sound sou ...
s and
broadcasting
Broadcasting is the distribution (business), distribution of sound, audio or video content to a dispersed audience via any electronic medium (communication), mass communications medium, but typically one using the electromagnetic spectrum (radio ...
.
Multicores often route many signals from microphones or musical instruments to a
mixing console
A mixing console or mixing desk is an electronic device for mixing audio signals, used in sound recording and reproduction and sound reinforcement systems. Inputs to the console include microphones, signals from electric or electronic inst ...
, and can also carry signals from a mixing console back to speakers.
In
audio engineering
Audio most commonly refers to sound, as it is transmitted in signal form. It may also refer to:
Sound
* Audio signal, an electrical representation of sound
*Audio frequency, a frequency in the audio spectrum
* Digital audio, representation of sou ...
, the term ''multicore'' may refer to the several things:
*an unterminated length of
multicore cable
A multicore cable is a type of electrical cable that combines multiple signals or power feeds into a single jacketed cable. The term is normally only used in relation to a cable that has more cores than commonly encountered. Not all cables with mu ...
intended for
analog audio
Analog recording is a technique used for the recording of analog signals which, among many possibilities, allows analog audio for later playback.
Analog audio recording began with mechanical systems such as the phonautograph and phonograph. L ...
signals (a type of
cable harness
A cable harness, also known as a wire harness, wiring harness, cable assembly, wiring assembly or wiring loom, is an assembly of electrical cables or wires which transmit signals or electrical power. The cables are bound together by a durable mat ...
)
*a terminated cable, with a multipin connector or many individual connectors
*the entire assembly of a terminated multicore cable and stage box
Applications
![Pats drums (2941761250)](https://upload.wikimedia.org/wikipedia/commons/e/e4/Pats_drums_%282941761250%29.jpg)
Multicores usually create a link between the
stage
Stage or stages may refer to:
Acting
* Stage (theatre), a space for the performance of theatrical productions
* Theatre, a branch of the performing arts, often referred to as "the stage"
* ''The Stage'', a weekly British theatre newspaper
* Sta ...
and
sound desk, or live room and control room. When used in sound reinforcement, the multicore cable runs from the
stage box
A stage box is an interface device used in sound reinforcement and recording studios to connect equipment to a mixing console. It provides a central location to connect microphones, instruments, and speakers to a multicore cable (snake), which ...
or
microphone splitter
Audio signal flow is the path an audio signal takes from source to output. The concept of audio signal flow is closely related to the concept of audio gain staging; each component in the signal flow can be thought of as a gain stage.
In typical h ...
to the
front-of-house sound desk, where it connects to a mixing console.
Portable multicore cables, stored loose or on a drum, enable sound systems to be set up at temporary outdoor locations such as
music festival
A music festival is a community event with performances of singing and instrument playing that is often presented with a theme such as musical genre (e.g., rock, blues, folk, jazz, classical music), nationality, locality of musicians, or h ...
s.
Permanent installations, especially
recording studio
A recording studio is a specialized facility for sound recording, mixing, and audio production of instrumental or vocal musical performances, spoken words, and other sounds. They range in size from a small in-home project studio large enoug ...
s, use stage boxes mounted in the floor or walls, with the multicore cable running through the
ceiling
A ceiling is an overhead interior surface that covers the upper limits of a room. It is not generally considered a structural element, but a finished surface concealing the underside of the roof structure or the floor of a story above. Ceilings ...
or
false floor.
Without a snake, a rock band performing onstage, for example, would require 20 or more individual microphone cables running from the stage to the mixing console (typically located at the rear of a venue). This would be harder to set up, would cause tangled cables, and it would be difficult to identify each cable.
Varieties
Terminations
Different termination methods can be used on each end to suit the application. When individual connectors are used, three pin
XLR connector
The XLR connector is a type of electrical connector primarily used in professional audio, video, and stage lighting equipment. XLR connectors are cylindical in design, and have three to seven connector pins, and are often employed for analog b ...
s are most common, although
phone connectors are occasionally used.
An end with many individual connectors fanning out is sometimes called a ''tail'' or ''fanout'', and generally connects directly to a mixing console.
The number of connectors on a multicore is often specified by notation such as "8/4" or "8×4" for 8 sends and 4 returns. ''Sends'' usually connect a microphone to a mixing console, and ''returns'' connect a mixing console to speakers.
A snake with only returns is often called a ''drive snake''.
Some systems use large multipin connectors, colloquially called ''mults'',
which make it easier to join snakes togetherfor example, to connect subsnakes to a main stage box. This allows the system to be expanded by channel count or length. Connectors based on
MIL-DTL-5015
MIL-DTL-5015 is a United States Military Standard which covers heavy-duty circular electrical connectors with soldered or crimped contacts. They are used for both digital and analog signals, as well as power distribution, and are common in v ...
(historically MIL-C-5015) are common.
Alternatives include EDAC, Burndy, and DB-25 connectors.
While the sound reinforcement industry often uses proprietary premade multicores, the
television
Television, sometimes shortened to TV, is a telecommunication medium for transmitting moving images and sound. The term can refer to a television set, or the medium of television transmission. Television is a mass medium for advertisin ...
broadcasting industry uses a standardized 12-channel multicore, with a common 37-pin connector on each end known as DT12. Only 36 pins are used and sometimes the unused pin is omitted. DT12 snakes are commonly built into sports venues and stadiums for easy connection of
outside broadcasting
Outside broadcasting (OB) is the electronic field production (EFP) of television or radio programmes (typically to cover television news and sports television events) from a mobile remote broadcast television studio. Professional video camera ...
trucks.
Subsnakes
A ''subsnake'' usually refers to a smaller multicore cable, or one not connected directly to the mixing console.
Subsnakes may be used to connect a few instruments from one side of the stage to the main snake, which is neater and allows for shorter
patch cable
A patch cable, patch cord or patch lead is an electrical or optical cable 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 sw ...
s. Subsnakes use smaller stage boxes called
''drop boxes''.
Composite multicores
Composite multicores combine different types of signals in the one cable. They may contain
coaxial
In geometry, coaxial means that several three-dimensional linear or planar forms share a common axis. The two-dimensional analog is ''concentric''.
Common examples:
A coaxial cable is a three-dimensional linear structure. It has a wire conduc ...
cores for
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) syste ...
,
twisted pair
Twisted pair cabling is a type of wiring used for communications in which two conductors of a single circuit are twisted together for the purposes of improving electromagnetic compatibility. Compared to a single conductor or an untwisted ba ...
for data or low
voltage
Voltage, also known as electric pressure, electric tension, or (electric) potential difference, is the difference in electric potential between two points. In a static electric field, it corresponds to the work needed per unit of charge to m ...
cores for mains power. Composite multicores are usually used to connect
professional video camera
A professional video camera (often called a television camera even though its use has spread beyond television) is a high-end device for creating electronic moving images (as opposed to a movie camera, that earlier recorded the images on film). O ...
s, but they are now gaining usage in
live event support
Live event support includes staging, scenery, mechanicals, sound, lighting, video, special effects, transport, packaging, communications, costume and makeup for live performance events including theater, music, dance, and opera. They all share th ...
with the introduction of the Yamaha PM1D which uses a composite cable to connect it to the
stage box
A stage box is an interface device used in sound reinforcement and recording studios to connect equipment to a mixing console. It provides a central location to connect microphones, instruments, and speakers to a multicore cable (snake), which ...
.
Breakout cables
An audio multicore may also function as a type of
breakout cable
Breakout-style fiberoptic cable (also called breakout cable or fanout cable), is an optical fiber cable containing several jacketed simplex optical fibers packaged together inside an outer jacket. This differs from distribution-style cable, in w ...
, sometimes referred to as a ''fan'' or some variation, if it has a compound (multipin) connector on one end and individual connectors on the other.
This is more common in short multicores meant for in-
studio
A studio is an artist or worker's workroom. This can be for the purpose of acting, architecture, painting, pottery (ceramics), sculpture, origami, woodworking, scrapbooking, photography, graphic design, filmmaking, animation, industrial design ...
connections, such as
audio engines,
analog-to-digital converter
In electronics, an analog-to-digital converter (ADC, A/D, or A-to-D) is a system that converts an analog signal, such as a sound picked up by a microphone or light entering a digital camera, into a digital signal. An ADC may also provide ...
s or
digital mixing consoles
Digital usually refers to something using discrete digits, often binary digits.
Technology and computing Hardware
*Digital electronics, electronic circuits which operate using digital signals
**Digital camera, which captures and stores digital i ...
. Multicore cables may also connect to either the front or back of
patch panel
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, when the patch panel is used as an access point or breakout box for connecting external inputs and outputs.
Cable construction
:''In this section, core refers to a single channel within a multicore cable, whilst conductor refers to a single wire.''
Core conductor arrangement
The vast majority of audio multicore cables consist of a number of twisted-pair
copper wire
Copper has been used in electrical wiring since the invention of the electromagnet and the telegraph in the 1820s. The invention of the telephone in 1876 created further demand for copper wire as an electrical conductor.
Copper is the electr ...
s, suitable for
balanced audio Balanced audio is a method of interconnecting audio equipment using balanced interfaces. This type of connection is very important in sound recording and production because it allows the use of long cables while reducing susceptibility to external ...
.
To reduce noise, the shield of each channel is often isolated from the other shields. Balanced connections may use XLR connectors or TRS phone connectors .
The broadcast industry tends to use audio multicores containing
star quad cable
Star-quad cable is a four-conductor cable that has a special quadrupole geometry which provides magnetic immunity when used in a balanced line. Four conductors are used to carry the two legs of the balanced line. All four conductors must be an ...
s, 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 screened independently. This reduces
crosstalk
In electronics, crosstalk is any phenomenon by which a signal transmitted on one circuit or channel of a transmission system creates an undesired effect in another circuit or channel. Crosstalk is usually caused by undesired capacitive, induc ...
between cables and also enables each cable to have a screen or ground that is isolated from other cables, significantly reducing the possibility of
ground loops which can cause unwanted hum.
A foil-screen is typically used, comprising thin aluminium wrapped around the group of conductors. An uninsulated drain wire is contained inside the screen to facilitate ground connection.
A less common construction is a lapped or braided screen comprising thin wires wrapped around the conductors. This gives 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 screening
A small number of multicore cables compromise twisted-pairs with only 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.
Overall insulation
Multicore cables usually have a thick PVC or
cross-linked polyethylene
Cross-linked polyethylene, commonly abbreviated PEX, XPE or XLPE, is a form of polyethylene with cross-links. It is used predominantly in building services pipework systems, hydronic radiant heating and cooling systems, domestic water piping, ins ...
sheath protecting the bundle of individual cables.
The PVC sheath is extruded around the inner cables, and solidifies to hold the cables in a tight group. This stops the cables from coming out of their tight braid (a phenomenon known as ''corkscrewing''),
and absorbs mechanical stress such as a person stepping on the cable.
A typical 48 channel multicore has an outside diameter of .
Core identification
Different cable manufacturers use different methods of identification for the shielded pairs of cable.
Belden 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 patented Beldfoil shield that is only
conductive
In physics and electrical engineering, a conductor is an object or type of material that allows the flow of charge (electric current) in one or more directions. Materials made of metal are common electrical conductors. Electric current is gener ...
on the inner surface. For their portable cables they use a
French braid
A French braid, also called a French plait, is a type of braided hairstyle. The three-strand gathered plait includes three sections of hair that are braided together from the crown of the head to the nape of the neck.
Description
In the simples ...
.
Canare,
Mogami,
Clark Wire & Cable and
GEPCO
Gujranwala Electric Power Company (GEPCO) ( ur, ) is an electric distribution company which supplies electricity to the Gujranwala region in Punjab, Pakistan. The jurisdiction of the company includes Sialkot, Narowal, Gujranwala, Gujrat, Hafiz ...
mark numbers on the
PVC insulation
Insulation may refer to:
Thermal
* Thermal insulation, use of materials to reduce rates of heat transfer
** List of insulation materials
** Building insulation, thermal insulation added to buildings for comfort and energy efficiency
*** Insulated ...
of the individual pairs.
Digital alternatives
Whilst traditional analog multicore cables are common in sound engineering, the advent of
digital mixing console
In professional audio, a digital mixing console (DMC) is a type of mixing console used to combine, route, and change the dynamics, equalization and other properties of multiple audio input signals, using digital signal processing rather than an ...
s have made so-called ''digital multicores'' favorable for many scenarios where multiple signals need to be run a long distance.
Whilst not technically a multicore cable, this newer system performs the same function, but comprises a
digital stage box connected directly to a mixing console through a single
twisted pair
Twisted pair cabling is a type of wiring used for communications in which two conductors of a single circuit are twisted together for the purposes of improving electromagnetic compatibility. Compared to a single conductor or an untwisted ba ...
or
fiber optic 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 ...
. The stage box converts between
analog
Analog or analogue may refer to:
Computing and electronics
* Analog signal, in which information is encoded in a continuous variable
** Analog device, an apparatus that operates on analog signals
*** Analog electronics, circuits which use analog ...
and
digital
Digital usually refers to something using discrete digits, often binary digits.
Technology and computing Hardware
*Digital electronics, electronic circuits which operate using digital signals
**Digital camera, which captures and stores digital i ...
signals with
DA and
AD converters.
This has the advantage of being much easier to set up and move, since only a single small cable needs to be run.
Digital audio
Digital audio is a representation of sound recorded in, or converted into, digital form. In digital audio, the sound wave of the audio signal is typically encoded as numerical samples in a continuous sequence. For example, in CD audio, sa ...
signals are also virtually insusceptible to
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, electros ...
, which is a great advantage in some applications such as long cable runs.
Sometimes the only cable run between the stage and sound desk is a single digital cable, and all audio processing occurs in digital format at the mixing console and stage box.
Common protocols used for digital multicores include
audio over Ethernet
In audio and broadcast engineering, Audio over Ethernet (sometimes AoE—not to be confused with ATA over Ethernet) is the use of an Ethernet-based network to distribute real-time digital audio. AoE replaces bulky snake cables or audio-specific i ...
and
AES10 (MADI).
References
{{reflist
Audio electronics
Signal cables