In the world of pro audio, there’s a multitude of a specialized gear at our disposal along with plenty of ways to connect them. While it might not be the most exciting topic, knowing what kind of audio cable is right for the job – as well as what they do – is just too important to ignore. While we will be covering the most common cables and connectors you will run across, this is by no means the complete list.
Originally invented for manual telephone switchboards, the standard 1/4-inch plug has been around since the late 1800s and is still the most common type of connectors for musicians. The TRS acronym stands for “Tip-Ring-Sleeve,” representing the three parts of the connector (Tip = positive, Ring = negative, and Sleeve = ground) and carries a balanced signal. Balanced signals are needed for longer runs of cable, as unbalanced signals can create noise over long distances.
The TS (Tip-Sleeve) version is a two-wire, unbalanced version. Due to their similar appearance and physical compatibility, it’s easy to confuse a TRS connector with a two-conductor unbalanced quarter-inch plug — and if you’re only hearing one side of your stereo field, chances are that’s exactly what you’ve done.
Standard quarter-inch TS plugs are most commonly used for guitar and other electrical instrument cables. The stereo versions are common on headphones, insert cables, and inputs and outputs on audio equipment that don’t need long runs of cable to connect — like studio mixers, compressors, and preamps.
If you’ve spent any time in a traditional recording studio, you’ve likely seen another variation of the TRS plug. The pro audio and telecommunications industries have long used TT (tiny telephone) connectors in patch bays. Slightly smaller than a standard quarter-inch connector, TT patch bays have been fairly ubiquitous in the racks and consoles of recording studios, their size allowing up to 96 jacks to fit into a standard 19-inch space.
In the past decade or so, smaller variations of the TRS/TS connector have become increasingly popular, including the miniature (eighth-inch) and subminiature (3/32-inch) versions now used by most phones and MP3 players.
Introduced by Cannon Electric (now part of ITT), XLR is sometimes still referred to as a cannon connector, or colloquially as “Extra Long Run,” referring to the extra long cables that can be used with this balanced connection.
The connectors are circular, with anywhere from three to seven pins. Most commonly, the balanced three-wire version has been the de facto standard for microphones for many years. Three-pin XLRs are also used for loudspeaker connections, low-voltage power supplies, lighting controllers, and a host of other applications. They also carry digital audio signals through the professional-grade AES/EBU protocol.
Unlike an analog XLR microphone cable, AES/EBU digital connections run two channels of digital audio over a single cable. Depending on the gear, common sample rates between 44.1kHz and 96kHz can usually run through this standard “Single Wire” mode. However, “Dual Wire” mode is sometimes needed in order to run at higher sample rates for ultra high-fidelity audio, such as 176.4kHz or 192kHz. This is where only one channel of audio can run over a single XLR cable.
Other variations of XLR connectors include four-pin versions, which are used as the standard for 12-volt power in the broadcast, film, and television industries. Five-pin XLR connectors are used for some stereo microphones, like the Shure VP88. Six-pin versions are used for some stage lighting applications and intercom systems, while seven-pin models are sometimes found on older condenser microphones which use their own power supplies (as opposed to phantom power).
Sometimes referred to as phono or cinch connectors, RCA is a two-conductor, unbalanced protocol commonly found on “prosumer” gear, as well as on turntables and consumer electronics. The RCA name comes from the electronics giant Radio Corporation of America (now a part of BMG), who introduced the design in the 1940s.
RCA connectors can also carry digital audio signals using the S/PDIF (Sony/Philips Digital Interconnect Format) protocol. They are also found on a wide range of computer audio interfaces and video equipment. Unlike an analog RCA cable, S/PDIF digital connections typically run two channels of audio over a single cable.
MIDI (Musical Instrument Digital Interface) cables have been used since the mid-1980s to interconnect computers, sequencers, keyboards, drum modules, effects boxes, and other devices, controlling them via MIDI data commands. MIDI connections also carry MTC (MIDI Time Code), which is used to synchronize DAWs, sequencers, instruments, and other MIDI-equipped devices.
These DIN-style connectors come in a variety of formats and pin configurations, but the five-pin MIDI variety is probably what you’re most accustomed to seeing. Unlike the other connectors we’ve talked about thus far, MIDI cables are strictly for data.
The banana connector (commonly banana plug for the male, banana socket or banana jack for the female) was invented by Richard Hirschmann, founder of the Hirschmann company, in 1924.
The plug is a single-wire (one conductor) electrical connector used for joining wires to equipment. The term 4 mm connector is also used, especially in Europe, although not all banana connectors will mate with 4 mm parts. The plug is a four-leafed spring tip that snaps into the jack. While they are often used as the plugs on the cables connecting the amplifier to the loudspeakers in hi-fi sound systems, banana plugs are also used to terminate patch cords for electronic test equipment.
US-style Dual Banana connectors contain two banana plugs, allowing simultaneous connection of a signal line and a ground (earth) line. The housing may allow the connection of individual wires, a permanently attached coaxial cable providing both signal and ground, or a coaxial connector such as the BNC connector.