Sound Card Guide
In a world of digital sound, sound cards have become synonymous with high-tech audio operations. For those of us who have not caught up with the latest, sound cards today can perform a variety of functions:
Making computer games and multimedia operation more fun
Compose, edit and mix music
Record and play digital audio from different sources
A modern PC sound card comes with a host of hardware systems. These relate to the production and capture of audio. The two major subsystems are for digital audio capture and replay and music synthesis. The second important component of a sound card is the digital audio section. This consists of a matched pair of 16-bit DAC (digital to analog) and ADC (analog to digital) converters and a programmable sample rate generator. The computer reads the sample data to and from one of these converters. It usually has a frequency of a fraction of 44.1 kHz.
Most sound cards today come with DMA (Direct Memory Access) channels. These are meant to read and write digital and audio data to and from the hardware. DMA- based cards that are used to implement simultaneous recording and playback use two channels. This increases the complexity of installation and can cause clashes between DMA and other hardware. To provide a direct digital output, many sound cards today use an optical or coaxial S/PDIF connection.
We often wonder how a sound card produces sounds at different pitches and speeds. This is made possible by the sound generator based on a DSP (digital signal processor) that multiplexes reads from different areas of the wave table memory at varying speeds and pitches to produce the desired effect. To find out the maximum number of notes available in a sound card, check its ‘polyphony’.
You have two options vis-a-vis the technology of a sound card: Frequency Modulation (FM) and Wave Table Synthesis. Almost all FM sound cards produce a similar output, but Wave Table cards vary a lot. You should consider all factors like frequency, quality of original recordings and compression methods before buying one.
Tip: Check the polyphony of a sound card for the number of notes and all factors that influence sound quality before buying a Wave Table card.
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