Cable Types Explained by Marc Schonbrun
There are a few types of cables that you'll have to deal with in your studio. You should know what each of them does; here is a breakdown.
Quarter-Inch Cables
The most common cable is the quarter-inch cable. It's the familiar “guitar cable” that we all know and love. These cables are used for connecting guitars and keyboards to amplifiers, amplifiers to mixers, and mixers to speakers, just to name a few. However, all quarter-inch cables are not created equal. There are specific types for specific uses. The most common is the instrument cable. The instrument cable is used for connecting instruments (guitars, keyboards, samplers) to amplifiers and other sources. The cable carries the mono (one-sided) signal to and from any source you choose.
Instrument cables are also commonly referred to as tip sleeve cables. If you look at the connection end, you'll notice that the tip is separated from the rest of the connector with a plastic spacer. The spacer separates the hot side of the cable that carries the signal from the side that carries the ground.
The other type of quarter-inch cable is the speaker cable. Speaker cables are very different from instrument cables. A guitar or a keyboard puts out a very small amount of power. Because of the potential for noise, which no one likes to hear in recordings, instrument cables contain a shield inside the cable to help keep the noise down. But amplifiers push more power to speakers through their cables than instruments do. Because of this, speaker cables don't need a shield, due to something called signal-to-noise ratio.
Signal-to-noise ratio is critical to understand. The higher the level of a signal, the less you hear the noise that is present. This is why you should never record low levels. Noise, while it's annoying, can usually be covered up by a full, loud signal.
Speaker cables shouldn't be used for instruments and vice versa. The packages clearly state what the cables are used for. When in doubt, ask for help.
Figure 8-1 shows all the connector types: quarter-inch TR (Tip-Ring), quarter-inch TRS, XLR, MIDI, and RCA.
Figure 8-1: Audio cable types
Tip Ring Sleeve Cables
The tip ring sleeve (TRS) is a quarter-inch stereo cable. Pull out any pair of stereo headphones that you own and look at the plug. Notice how it was two plastic spacers? The quarter-inch tip sleeve (instrument) cable has only one. The extra spacer on the tip ring sleeve is there to accommodate another signal in the cable. Stereo cables carry two separate signals: left and right.
In a studio, a stereo cord is used for two purposes. First, it connects an effect processor into a mixer or recording device. This type of cable is called an “insert.” Insert cables have the stereo connector on one side and two mono cables on the other side. The stereo cable splits the signal so that you can have an input and an output to an effects processor. In short, if you're going to use external effects, you'll need to own a few stereo insert cables.
The second use for a stereo quarter-inch cable is for a balanced signal. Balanced cables have a stereo plug on both sides. What does balanced mean? Basically, the cable copies one signal to the two internal wires and performs extra shielding and other electrical magic to cut down the noise. Balanced cables are used for microphones and whenever cord lengths are very long. This helps cut down on the noise that longer cables usually have.
XLR Cables
XLR is the standard microphone cable, and the letters stand for the three signals carried in the cable. X is for external, which is called the ground, L is for line, and R is for return. The connector is round and has three prongs on one side (the male side) and three sockets on the other (the female side). Microphone cables are always balanced. XLR cables are sometimes used for connecting mixers to recording devices, but their most common use is for microphones.
Balanced cables can be used only if your mixer or recording device supports them. It will be clearly stated in your manual if you can use a balanced signal. You find balanced connections on better recording equipment. Microphone inputs are always balanced.
RCA Cables
RCA cables, invented by the RCA Corporation, are another type of unbalanced cable. They are typically two mono cables that run together and split off into two ends with RCA plugs. RCA cables are commonly used in home stereo equipment. In the recording studio, RCA cables are used to hook up a tape machine to a mixer and recording interfaces to some computers.
Digital Cables
Digital audio cables fall into three categories:
The S/PDIF digital cable carries one stereo signal digitally on an RCA cable.
The AES/EBU cable carries the same stereo digital signal, this time on XLR cables.
Fiber optic cables are used for audio.
Digital cables can transmit a stereo pair, or in the case of ADAT Light-pipe, eight signals at once! Digital connectors are very common on recording equipment today—even lower cost ones.
MIDI Cables
MIDI cables are simple, and there is only one type: the five-pin MIDI. You can't possibly buy the wrong one. If your MIDI interface has MIDI connector jacks, then you'll need one cable for each input and one cable for each output you want to use.
