Audio multicore cable

Multicores usually create a link between the stage and sound desk, or live room and control room. When used in sound reinforcement, the multicore cable runs from the stage box or microphone splitter 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 festivals. Permanent installations, especially recording studios, use stage boxes mounted in the floor or walls, with the multicore cable running through the ceiling 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 connectors are most common, although phone connectors are occasionally used. connectors. While the sound reinforcement industry often uses proprietary premade multicores, the television 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 trucks. Subsnakes A subsnake usually refers to a smaller multicore cable, or one not connected directly to the mixing console. This is more common in short multicores meant for in-studio 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 panels, 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 wires, suitable for balanced audio. 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 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 individual 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 feature multiple twisted pairs with only a single 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 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), for their plenum cables each pair is covered with their patented Beldfoil shield that is only conductive on the inner surface. For their portable cables they use a French braid. Canare, Mogami, Clark Wire & Cable and GEPCO mark numbers on the PVC insulation of the individual pairs. == Digital alternatives ==

Whilst traditional analog multicore cables are common in sound engineering, the advent of digital mixing consoles have made so-called digital multicores favorable for many scenarios where multiple signals need to be run a long distance. 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 and AES10 (MADI). ==References==