Interconnects are cables that connect line level (non-amplified
) stereo components (e.g. from CD player to pre-amp). Their most common manifestation is the red and white RCA
tipped cables that ship with every piece of consumer electronics on the planet (VCRs, tape decks, TiVOs, CD players, DVD players, etc.)
There are two general classes of interconnects based on the type of signal they carry: analog and digital.
Among analog interconnects, there are, again, two types: single-ended and balanced.
Single ended is the format most people are familiar with. They are the type used by every mass-produced component on the market. Usually they are coded with a red connector and white connector on each end. Single-ended interconnects use RCA type terminations and 2 (signal and ground) conductors (excluding shielding). Often the shielding is electrically connected to the ground conductor at the source end of the cable, this reduces the amount of noise picked up from RF sources. It also makes the cable "directional" in the sense that it performs better when the shield-ground connection is at the source end. Cables with this type of shielding are marked with arrows to indicate the proper orientation. Multi-conductor variants like the Nordost "Blue Heaven" use 36 conductors, half for signal, half for ground.
Balanced interconnects use 3 conductors and a symmetrical signal. They are used throughout professional audio (e.g. microphone to mixer) because even very long runs are almost immune to picking up noise. They are also used in high end stereo connections for the same reason. Balanced interconnects are most frequently terminated with XLR type connectors.
Digital interconnects move data between a digital transport and an outboard DAC or digital surround processor. There are several types of digital interconnect. Both TosLink and coaxial transmit S/PDIF formatted data, and Balanced types transmit using the AES/EBU standard and are terminated with XLR connectors.
TosLink is an optical connection, using plastic or glass optical fiber to move the data.
Coax connections are similar to regular single-ended analog interconnects, though their impedance needs to be as close to 75 ohms as possible to avoid echoes and signal smearing.
AES/EBU interconnects use a balanced connection and are found on professional and high end audio equipment. They use 3 conductors and a symmetrical signal configuration which allows for noise rejection, they require a 110 ohm cable. There is also the I2S type connection, it transmits the different signal types and clock sync information in 4 separate lines, avoiding jitter. However, this type of interconnect is uncommon and only supported by a few manufacturers.