Sound card facts for kids
A sound card (audio card) is the part of the computer hardware that controls the input and output of the sound signals. A sound card is what is known as an expansion card. This means that the card can be added to the motherboard.
Nowadays, most of the audio cards are integrated with the motherboard. That means they are built into a mainboard and can not be removed. In other words, it is not an expansion card anymore. They only offer line-in, speaker, and microphone connections. For most users this is enough. When thinking of computer architecture, the integrated circuit sound cards occupy less space and thus became very popular and practical, especially for laptop computers. For more features like MIDI ports for connection of musical instruments and low latency requirements (so that the sound does not come distorted under heavy system usage) sound cards as expansion cards can be used. Modern expansion sound cards use the PCI computer bus standard. Earlier sound cards used the ISA computer bus, which was half-duplex, so the sound cards could not record and play simultaneously.
Input and output signals
What we hear in speakers is an analog (current, voltage or electric charge) output of the signal. For example, stored on a hard disk digital code is transferred under a control of some application (for example Winamp) to the sound card. Up in there, a special chip, called digital-to-analog converter, changes the binary code into the analog sound. Afterwards, signal is sent to a jack (in modern audio cards it has the green color) where the speakers are connected. The result is a nice waveform of our favorite digital medium, e.g. an mp3.
A typical sound input device is a microphone, connected to the red/pink jack socket. The sound wave is digitized and then it may be stored as a file using data compression algorithms which make the file smaller. Of course all of this is done under the control of some software.
Color codes
Connectors on the sound cards are color-coded as per the PC System Design Guide. They may also have symbols of arrows, holes and soundwaves that are associated with each jack position.
| Color | Pantone | Function | Type | Connector | Symbol | |
|---|---|---|---|---|---|---|
| Pink | 701 C | Analog microphone audio input | Input | 3.5 mm minijack | A microphone | |
| Light blue | 284 C | Analog line level audio input | Input | 3.5 mm minijack | Arrow going into a circle | |
| Lime | 577 C | Analog line level audio output for the main stereo signal (front speakers or headphones) | Output | 3.5 mm minijack | Arrow going out one side of a circle into a wave | |
| Orange | 157 C | Analog line level audio output for center channel speaker and subwoofer | Output | 3.5 mm minijack | ||
| Black | Analog line-level audio output for surround speakers, typically rear stereo | Output | 3.5 mm minijack | |||
| Silver/Grey | 422 C | Analog line level audio output for surround optional side channels | Output | 3.5 mm minijack | ||
| Brown/Dark | 4645 C | Analog line level audio output for a special panning, 'Right-to-left speaker' | Output | 3.5 mm minijack | ||
| Gold/Grey | Game port / MIDI | Input | DA-15 | Arrow going out both sides into waves | ||
Images for kids
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Close-up of a sound card PCB, showing electrolytic capacitors, SMT capacitors and resistors, and a YAC512 two-channel 16-bit DAC
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8-channel DAC Cirrus Logic CS4382 placed on Sound Blaster X-Fi Fatal1ty
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The AdLib Music Synthesizer Card, was one of the first sound cards circa 1990. Note the manual volume adjustment knob. ISA-8 bus.
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Sound card Mozart 16 for ISA-16 bus
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A Turtle Beach sound card for PCI bus
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Echo Digital Audio's Indigo IO – PCMCIA card -bit 96 kHz stereo in/out sound card
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A VIA Technologies Envy sound card for PC, 5.1 channel for PCI slot
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Three early ISA (16-bit) PC sound cards showing the progression toward integrated chipsets
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A pair of professional rackmount audio interfaces
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Professional audio interfaces often have industry-standard inputs in addition to analogue audio, in this case ADAT, TDIF, and S/PDIF
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USB sound card
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Turbo Sound board manufactured by NedoPC, revision A
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See also
In Spanish: Tarjeta de sonido para niños
