Sound card connections and color codes

A sound card (also called audio card) is the part of a computer which manages its audio input and ouput. Nowadays, computers usually have it integrated on their motherboard. In this article we will introduce this important component.

Sound card connectors

The main elements of a sound card are:

  • The specialized processor, called the DSP (digital signal processor), which does all the digital audio processing (echo, reverb, vibrato chorus, tremelo, 3D effects, etc.).

  • The digital to analog converter, or DAC for short, which converts the computer's audio data into an analog signal for being sent to a sound system (such as speakers or an amplifier).

  • The analog to digital converter, or ADC for short, which converts an analog input signal into digital data which a computer can process.

PCI sound card

External input/output connectors

  • One or two standard 3.5 mm line-out jacks, normally light green in color.
  • A line-in jack.
  • A microphone input (sometimes called Mic), usually a pink-colored 3.5 mm jack.

  • An SPDIF digital output. This is an output line which sends digitised audio data to a digital amplifier using a coaxial cable with RCA connectors at the ends.

  • A MIDI connector, usually gold-colored, which is used for connecting musical instruments, and can serve as a game port for plugging in a controller (like a joystick or gamepad) which has a SUB-D 15-pin connector.

Internal input/output connectors

  • A CD-ROM/DVD-ROM connector, with a black socket, which is used to connect the sound card into a CD-ROM's analog audio output using a CD Audio cable;

  • Auxiliary inputs (AUX-In), with white sockets, used for connecting internal audio sources such as a TV tuner card;

  • Telephone answering device connectors (TAD), which have a green connector.

Color codes

  • Pink:
    • 701C
    • Analog microphone audio input
    • 3.5 mm minijack
    • Symbol: a microphone
  • Light blue:
    • 284C
    • Analog line level audio input
    • 3.5 mm minijack
    • Symbol: an arrow going into a circle
  • Lime
    • 577C
    • Analog line level audio output for the main stereo signal
    • 3.5 mm minijack
    • Symbol: arrow going out one side of a circle into a wave
  • Orange
    • 157C
    • Analog line level audio output for center channel speaker and subwoofer
    • 3.5 mm minijack
  • Black
    • Analog line-level audio output for surround speakers
    • 3.5 mm minijack
  • Silver/Grey
    • 422C
    • Analog line level audio output for surround optional side channels
    • 3.5 mm minijack
  • Brown/Dark
    • 4645C
    • Analog line level audio output for a special panning
    • 3.5 mm minijack
  • Gold/Grey
    • Game port / MIDI
    • 15 pin D
    • Symbol: arrow going out both sides into waves

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