Audio cables seem simple enough, but when you begin shopping you quickly discover that they vary greatly in purpose, price, and quality. This guide will help you sort out the various types of cables and connectors, and will demystify the jargon used to describe them.
Cable Quality Levels
The basic purpose of a cable is to move an electrical signal from one component to another without degrading the signal significantly or introducing noise. There are expensive, audiophile-quality cables that are designed and constructed to keep the signal pristine and noise-free. Most musicians do not need quite this level of cable performance for their stage gear, but still you want cables of high quality. Quality cables will deliver better sound, and if you sound better, you’ll play better.
Other “quality” features, such as gold-plated connectors and oxygen-free copper wire, are not necessarily important. Gold-plating may lessen resistance, but is more subject to wear than nickel-plating, so may be a liability on connectors that are plugged and unplugged a lot. Oxygen-free wire may offer slightly less resistance, but larger gauges help more.
Mainly you want cables that are flexible, durable, and that have quality hardware and well-soldered connections. Other features are epoxy potted or hot glue connectors (filled with one substance or the other to prevent the wire ends from moving) and heat shrinking on the ends of the cable (a plastic sleeve around the wires and terminals that is heated to shrink it to a tight fit that keeps the wires from moving). Instrument cables especially need to be durable. They move, get pulled, stepped on, and plugged in and unplugged frequently. No instrument cable will last forever, but good ones last longer. You also want to buy cables that are sufficient in length, but not excessively long (the longer a cable is, the more susceptible it is to noise).
Types Of Cable By Function
Musicians are generally concerned with cables that fall into four basic categories: instrument cables, patch cables, speaker cables, and microphone cables. The number-one rule is to buy a cable designed for your specific purpose. An instrument cable should not be used to connect a speaker. It will work but not properly and, under some circumstances, can cause problems. And you never want to use a speaker cable as an instrument or patch cable because it is unshielded and extremely susceptible to sources of noise.
|Instrument cable: As the name implies, it connects a guitar, bass, keyboard, or other electronic instrument to its amplifier. It has a positive wire and shielding that serves as a ground. It is designed to carry low voltage instrument signals and most often uses 1/4" phone plug connectors.||Patch cable: A short cable used to link various components in a PA or recording setup, or to link effects pedals to each other and to the instrument-to-amp circuit. Most often patch cables are similar to instrument cables, but they can also be balanced (explained below), and can have various kinds of connectors (XLR, 1/4" phone, TRS, RCA).|
|Microphone cable: A shielded and balanced cable with an XLR male connector on one end and an XLR female connector on the other. Some microphone cables have a TRS mini plug or USB connector on the delivery end for plugging directly into a computer sound card or digital recording device. A mic cable is often used as a long, balanced patch cable linking a mixing board with a powered speaker. Similarly, a mic cable is often used for a D.I. connection between an amp and a mixing console. Mic cables are also sometimes used for AES/EBU digital output.||Speaker cable: An unshielded two-wire cable of a much larger gauge than a patch, instrument, or mic cable. Speaker cables need bigger wires because they carry much higher voltage signals. Even mains cable can be used as a speaker cables. They can have 1/4" phone, banana clip (also called MDP connectors), binding post (as commonly found on stereo amplifiers), or Speakon connectors.|
|Multi Core/Snakes: Snakes are essentially bundled sets of cables. Stage snakes may contain microphone, patch, or speaker cables and are used for two-way connection between the stage and a remote mixing and effects station. They have a fan of connectors on one end, and a box on the stage end that houses a panel of connectors. In shopping for a snake, the length and the type of connections are the main considerations. There are also audio snakes for studios that bundle various cables needed for connecting studio components.|
Balanced And Unbalanced Cables
Patch cables can be balanced or unbalanced. Balanced cables are quieter than the unbalanced type and are used in more critical applications where line noise can be an issue. Unbalanced cables are more common and simpler. They are two-conductor cables having a conductor and a ground, and usually have tip/sleeve (TS) phone connectors. Balanced lines are three legged, having two conductors—a positive and a negative—plus a shielding ground. Because balanced cables have more wires to connect, they require XLR or tip/ring/sleeve (TRS) phone connectors. Signals are carried simultaneously on both conductors and reversed polarity cancels out any line noise that is generated. Because balanced lines are noise-canceling, they can be longer than unbalanced cables without creating noise problems. Unbalanced cables longer than 10' are susceptible to line noise and amplify ground loops.
It is important not to mistake single stereo cables with balanced mono cables. Though they use the same TRS connectors, they are wired differently and are application specific.
All audio cables with the exception of speaker wires and optical cables are shielded to protect the signal from interference that causes noise. The shielding is most often a wire braid that surrounds the insulator for the center conductor(s). The purpose of shielding is to protect the signal from sources of noise, such as radio transmissions, AC power cords, fluorescent lighting, rheostat dimmers, and some appliances. When you hear radio chatter through your amp, it usually means that the shielding around your amp’s gain components is inadequate, but your instrument cable’s shielding can also be implicated. Good shielding blocks interference and also may serve as a ground.
There are several types of shielding. The most common is the braided shield. Small wire strands are braided to form a sheath around the insulation of the current-conducting wire. This type of shielding is flexible and durable. Onstage mic and instrument cables are constantly being bent, pulled, and stepped on, and braided shielding holds up best under these conditions.
Another type of shielding is the spiral-wrapped or serve shield. This sheath is formed by wrapping a flat strip of wire strands around the center wires in a spiral. The serve shield, while it lacks the tensile strength of a braided shield, is more flexible than a braided shield because it stretches when the cable is bent. It is less resistant to radio frequency (RF) interference, because it is actually a coil and has inductance. It is also easier to manufacture so cables using serve shielding are usually less expensive.
The foil shield is yet another kind of shielding. It is a mylar-backed aluminum tube with a copper drain wire connected at each end. This is the kind of shielding used in thin patch cables such as the RCA-ended connecting wires that link stereo system components. Foil shielding is cheap and easy to manufacture and can be an effective shield, but is fragile and can easily be damaged by flexing. It is best used in non-critical applications where the cables stay put, such as stereo cables that once connected aren’t moved.
Types Of Cable Connectors
|TS 1/4" phone jack: This is the most common connector and is used on unbalanced patch cables, instrument cables, and speaker cables. TS stands for tip and sleeve. The hot wire of the cable connects to the tip, the ground (usually the shielding) attaches to the sleeve.||TRS phone jack: this jack looks like the TS 1/4" phone jack but has an extra segment in the shaft called the ring. The tip, ring, and sleeve allow connection of two wires as well as a ground. TRS connectors are used for balanced cables, stereo, and can serve as a single jack for in and out signal flow. Often channel insert points use TRS jacks as an in/out connection to an effects unit.|
|XLR connectors: XLR male and female connectors are those you see on the ends of microphone cables. They are three-pin connectors and are also used on balanced patch cables, for sending a balanced signal from a mixing board to powered speakers, and on DMX-enabled lighting equipment.||Phono/RCA connectors: Most commonly used on consumer stereo equipment, CD players, and turntables, RCA cables are usually a pair of wires molded together so that only the ends are separate. Many mixing boards have RCA inputs for connecting a stereo CD player to a PA system, and some mixers also have RCA outputs for connection to recording devices.|
|Banana plug: this is a two-pronged connector used on speaker cables, often on just the amp end, but on both ends when the speakers have the appropriate jack. The main advantage of the banana plug is that the wires are not soldered. The end of the wire slips into a hole and is held in place by a locking screw. This simple design allows fast repairs on the fly.||Speakon connectors: Speakon connectors are being used more and more for connecting speakers in PA systems. They are desirable because they lock and can’t be inadvertently pulled out, as can banana plugs or phone jacks.|
|1/8" mini jack: These jacks can be either TS or TRS. They are used frequently on digital recording gear and sound cards where a small jack is required. They are also used on lightweight headphones, instrument cables that plug into body pack transmitters of wireless systems, and many consumer electronics devices.||D-Sub cables and connectors: D-sub is an abbreviation of D-Subminiature and is used as a prefix to describe multi-pin connectors commonly used in audio equipment. D-Sub connectors come in 9-, 15-, 25-, 37, and 50-pin configurations. The DB25 size D-Sub is commonly used by some audio brands (Tascam and others) for analog/digital I/O. Mackie mixers use the DB25 for connecting to a FireWire interface. DB25 connectors are also used in some audio snakes for analog connections, particularly those using the Tascam standard.|
As you add equipment and as technologies change, you may find you need a cable with an unusual combination of connectors. We recommend you consult with us for technical assistance. Our staff try to keep up on new developments and knows what is available. They can refer you to the specific cable you need or recommend a proper adapter.
If you have a PA system that you use routinely for gigs, a cable tester is a piece of gear worth investing in. Cables can fail, or fail intermittently, and a cable tester can quickly tell you where the problem is and what kind of problem it is.
Digital Cables And Connectors
The connectors described above are the primary analog connectors and cables used for PA systems, instrument setups, and traditional studios. Now digital technology has added many types of connectors and cables that connect computer serial buses to various peripherals such as printers, drives, interfaces, digital recorders and processors, video equipment, and DJ gear. The many different cables, connectors, and protocols reflect the continual changes in digital technology. New technology is often accompanied by new protocols involving computer hardware, software, and drivers. What follows is a description of some of currently most common connectors and cables. One important caution is that often digital gear uses the same type of connectors as analog gear (XLR and RCA connectors, for example), but the cables are usually designed for different resistances and therefore are not interchangeable with similar looking analog cables.
|MIDI: The name MIDI is an acronym which stands for Musical Instrument Digital Interface. It’s a protocol developed to allow electronic instruments and peripheral devices to communicate. It transmits every aspect of a musical performance except audio—that is, what note is keyed, how long it is held, the velocity of the strike, etc.—while the actual tone is generated by the connected sound module. MIDI can also transmit control parameters to software and synths, allowing you to virtually turn knobs and push sliders using a MIDI-enabled remote control surface.||USB: this relatively new type of computer connection has become a standard for connecting peripherals such as printers, cameras, musical instruments, and digital audio gear. USB cables have type A or type B connectors on one end, and another connector specific to the device being connected on the other. USB can also serve as a power source for the connected device. In the years since its introduction, specifications have been upgraded from the original 1.1 standard, to the 2.0 standard, the primary difference being that the latter can transfer data at a faster rate. USB 2.0 is backward compatible with the 1.1. A third, newer USB connector is the mini USB jack, often seen on MP3 players and on some of Roland’s gear.|
|FireWire (IEEE 1394): A protocol first developed for video because it allows high-speed data transfers up to 800 mbps; now widely used for audio applications. Currently there are three kinds of FireWire connectors: 4-pin, 6-pin, and 9-pin. The 4- and 6-pin versions are known as FW400. The 9-pin version is known as FW800. The 6-pin has the same data-transfer speed as the 4-pin but can supply power. The 9-pin supplies power and is twice as fast as the 6 or 4. Adapters are available when you need to link devices requiring different connectors. The FW800 is backwards compatible with the other two, but not vice versa.||S/PDIF: An abbreviation for Sony Philips Digital Interface Format. This interface for digital audio uses either optical or coaxial cables for transmission. The coaxial version uses RCA plugs but these cables are not interchangeable with analog RCAs, as the S/PDIF versions must be 75 ohms. The optical version uses TOSLINK, which is a connection developed by Toshiba. Both versions are capable of carrying two audio streams, typically the left and right channels of a stereo signal.|
|AES/EBU: An interface format for digital signals developed by the Audio Engineering Society (AES) and European Broadcasting Union (EBU) in the early 1980s. It uses AES Type 1 cabling—a three-conductor, 110-ohm cable and XLR connections. It transfers two channels through one connection and is the transfer protocol which S/PDIF is based on. Because of differences in resistance, an XLR microphone cable, although it has the same connectors, will not work as an AES/EBU cable.||BNC connectors: The BNC is a bayonet-style connector often found on cables that carry synchronizing clock signals between digital studio components. They are also found on video equipment and audio testing devices. Sometimes in a non-digital application, mixing boards have a BNC connector for plugging in a gooseneck lamp.|
|Optical cables and connectors: fiber-optics technology is often used in digital devices for data transfer. Optical cables convey data as light and are noise-free. Many digital devices have dual ports, one coaxial, the other optical. One important optical protocol is ADAT Lightpipe. It transfers eight channels of digital audio on a special cable with an Alesis-specific ADAT connector.||TDIF: (Tascam Digital Interface) is a proprietary format that uses a 25-pin D-sub cable to transmit eight channels of digital audio between compatible devices. It allows bidirectional connection, meaning that only one cable is required to connect the eight ins and outs of one device tor another. The older TDIF-1 cannot send or receive sync information (a separate wordclock connection is needed). The newer TDIF-2 protocol can receive and transmit sync without additional cabling.|