Let’s review the ground we covered in the first couple of installments: The sound source or microphone connects to the audio interface which links to the computer and recording software, often through a USB or FireWire cable. The stereo outputs of the interface plug into to the inputs of the speakers which amplify the recorded signal for you to hear.
Speakers come a variety of shapes and sizes. Some are small enough to fit in your cell phone and others are powerful enough to fill an arena with sound. Consider the electric signal of a recorded sound to be a snapshot of what that sound looks like. The purpose of the speaker is to make that picture much larger without negatively affecting the quality of the image.
In order to translate an electrical signal into an audible sound, speakers contain an internal electromagnet – a metal coil that generates a magnetic field when current flows through it. This electromagnet sits in front of a permanently placed magnet. As signal passes through the coils of the electromagnet, the direction of the magnetic field changes rapidly allowing it to move towards and away from the magnet, causing vibrations. A cone made of thin material, often paper or plastic, attached to the electromagnet amplifies these vibrations and pumps sound waves into the air for you to hear. The frequency of these vibrations determines the pitch of the sound. If you listen back at a loud enough level, you will be able to see and feel the cone of the speaker moving back and forth.
All speakers, regardless of size, make or model, fall into one of two categories: active and passive. Active speakers contain a built-in amplifier. They are often more expensive than passive speakers, which require a separate external power amplifier. Power amplifiers connect to speakers by speaker cable, which can handle more signal than a standard 1/4” instrument cable.
There are a few basic cables commonly used in the studio. Balanced three-pin XLR cables, also known as mic cables, are most often used to connect a microphone to a recording input. These three pins correspond to the three wires within the cable: a positive leg and a negative leg, which carry the same signal in opposite phases to one another, and the shield, which protects the audio signal from external noise and interference.
There are two different kinds of 1/4” cables. Tip/Sleeve (“TS”) cables have two internal wires: one inductor carrying the signal and one acting as a shield. This is considered unbalanced. You can identify this by looking at the end of cable to see that there is one ring around the connector. These cables are often used to connect a guitar or bass to an amp. Tip/Ring/Sleeve (“TRS”) cables have two conductors carrying signal plus a shield. This means they’re considered balanced and have two rings around the shaft of the connector
1/8″ to 1/4″ Cables
There are several combinations of connectors and adapters that can be used to hear your sounds through various devices. Use a mono 1/8” to stereo 1/4” cable to connect your phone or iPod directly into speakers or an amplifier. RCA to 1/4” cables allow you to connect the RCA outputs of a record player to speakers that may not have RCA inputs. Every speakers is different, so take a look and figure out what kind of inputs and outputs your equipment has. You’ll likely be able to find any kind of connection cable at your local music store.