When building a new PC system or replacing failed or obsolete components, you'll need to consider whether audio performance plays an important part in your computer needs. Motherboards with integrated audio are now common, so sound cards are no longer as much of a "must have" component for the workplace. However, businesses with greater multimedia demands may still prefer the benefits of more sophisticated sound cards, and media professionals have their choice of pro-quality external audio devices.
Sound Card Overview
Up until the mid-to-late 1980s, computers were largely incapable of anything but the most basic sounds. Although personal computers from Apple and Commodore offered some audio flexibility via built-in sound chips and third-party expansions, the IBM PC was limited to primitive beeps from the internal PC speaker. By the end of the decade, companies such as AdLib and Creative began producing the first "modern" sound cards, and further refinements focused on ways to improve sound quality as well as to relieve CPUs and shared memory from the considerable demands of processing audio.
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Sound Card Connections
The initial sound card designs used ISA (Industry Standard Architecture) to connect to the PC motherboard, but by the end of the 1990s nearly all sound card manufacturers had adopted the superior PCI architecture. Also around the turn of the century, external audio interfaces began appearing -- first as "breakout boxes" attached to a PCI card, then more commonly plugged into USB or FireWire ports. Ultimately, more efficient and sophisticated hardware allowed audio processing to be reintegrated on the motherboard for most casual or mainstream PCs, while external interfaces became more common among mobile and professional audio users. However, PCI-Express (PCIe) sound cards are still widely available for users who prefer discrete audio components.
Sound Card Design
A basic sound card consists of a set of audio inputs and outputs connected to a digital-to-analog converter (DAC) which translates electrical sound signals into binary data. Once the audio signal is digitized, it can be processed and manipulated in the PC like any other form of data. However, doing this in real time is extremely demanding for a computer, and many of the early sound cards were only "half-duplex," meaning that they could only play or record at any given time, not both. This was sufficient for things like listening to music or playing games, but not for voice communication or musical applications. Additionally, many manufacturers equipped sound cards with sound-generating devices such as synthesizers, placing further demands on the audio processing power. The usual effect of underpowered sound cards was an increase in "latency," the gap in time between when a sound event occurs and when you actually hear it.
Initially, sound cards offered only analog stereo output, although most featured both a line-level and headphone-level jack. As sound card capabilities increased, the number of audio formats and channels multiplied, and it is now rare to find a sound card that does not support digital outputs and 5.1 or 7.1 surround sound (five or seven audio channels plus a subwoofer channel). Likewise, audio inputs on the most basic basic sound card may be limited to a "mic in" for directly connecting a microphone, but many also feature higher-quality line input and digital input. The vast majority of input and output jacks are of the standard 3.5mm format, but SPDIF digital jacks are not uncommon, and several manufacturers make sound cards and external interfaces with "prosumer" RCA or Toslink jacks, or studio-quality ¼" TRS or XLR jacks.
Sound cards can come with a number of options tailored to specific needs. A common feature on the sound cards of the 1990s and early 2000s was the joystick port, which often doubled as a MIDI interface for sending and receiving data from external synthesizers and other music production equipment. USB has since replaced the need for dedicated controller ports, but standard 9-pin MIDI interfaces can be found on many professional audio interfaces. Built-in preamps are also found on many soundcards, both output preamps for higher-quality headphone or speaker listening and input preamps for improved microphone performance.
Advantages and Disadvantages
Your audio needs will determine the type of sound card that you need, or even if you need one at all. The vast majority of motherboards feature built-in audio hardware by companies like Realtek, which provide sufficient sound options to satisfy most business users. If you do need a discrete card, or if your audio needs are more extensive, don't dismiss products marketed for gamers and home theater enthusiasts; sound cards from Creative, Asus, HT and others can provide the higher audio quality and more flexible connectivity that business professionals need for multimedia presentations and video conferencing. If your business involves studio-quality video and audio production, you'll want to examine external audio interfaces from M Audio, Echo, Focusrite or any of a number of other pro audio manufacturers.