Cirrus Logic Audio Codec Furnishes CD-Quality Sound in New Apple iMac Computer

In conjunction with the shipping of Apple's iMac computer, Cirrus Logic Inc. disclosed details of the new custom Crystal audio codec (CS4211) that provides high-performance audio processing in Apple's new machine.

According to Cirrus Logic, the CS4211 processes audio at a dynamic range of 93 dB unweighted and 96 dB A-weighted. PC'98 standards only require a dynamic range of 80 dB A-weighted. The device also has a total harmonic distortion level of 85 dB THD, much lower than the PC'98 requirement of 60 dB THD. This level of digital audio processing allows iMac users to connect their computers to powerful, high fidelity equipment to mix different sound sources and hear the level of audio quality they would get from a CD player.

Digital bass and treble implementation limits distortion and inaccuracy while allowing for audio quality control superior to that of a home stereo system. A revolutionary digital mixing topology allows users to configure the audio system to control what is recorded, what is heard through speakers, and how that sound is processed.

This flexible circuitry, which digitally implements bass and treble, also implements SRS, a stereo enhancement algorithm to improve the audio. Unlike current audio codec solutions, Cirrus Logic's chip takes each sound source and converts it from analog to digital so mixing can be done digitally. Thus, the analog noise floor is no longer a constraint, so mixing does not introduce noise.

Cirrus Logic has a long-standing relationship with Apple concerning the supply of audio devices in high production volumes.