SACDs vs. CDs
A compact disc is recorded with 16-bits of resolution at a sampling rate of 44.1 kHz. SACD players and discs are based on Direct Stream Digital (DSD) processing, a 1-bit format with a sampling rate of 2.8224 MHz, which is 64 times the rate of a standard compact disc. The higher sampling rate results in wider frequency response and audio reproduction with more detail. The frequency range of a CD is 20 Hz to 20 kHz, roughly equivalent to human hearing. (This changes from person to person, and our hearing range diminishes somewhat as we age.) SACDs frequency range is 20 Hz to 50 kHz. The dynamic range of a CD is 90 decibels (dB). The dynamic range of SACD is 105 dB. For context, the range for human hearing is up to 120 dB. Testing to find if people can hear the difference between CD and SACD recordings has been performed, and the results generally indicate that the average person cannot tell the difference between the two formats. The results, however, are not considered conclusive.
Types of SACD Discs
There are three types of Super Audio Compact Discs: hybrid, dual-layer, and single layer.
Hybrid discs have two layers: a higher performance layer that can play only on SACD-equipped players, and a CD layer that plays on standard CD players. Additionally, some Hybrid SACD discs have both a 5.1 channel surround track and a stereo track. The multichannel track can only be played on multichannel SACD players. Single-layer SACD discs play only on SACD-equipped players and not on standard CD players. Dual-layer discs store twice as much music as a single-layer disc but don’t play on CD players and are not as common.
Advantages of SACD
Even a modest stereo system can benefit from the increased clarity and fidelity of SACD discs. The higher sampling rate (2.8224 MHz) contributes to extended frequency response, and SACD discs are capable of greater dynamic range playback and detail. Since many SACD discs are hybrid types, they play on SACD and standard CD players, so they can be enjoyed on a home audio system, as well as car or portable audio systems. They cost slightly more than regular CDs, but many think their superior sound quality is worth the higher cost.
SACD Players and Connections
Some SACD players require an analog connection (either 2 channel or 5.1 channel) to a receiver to play the higher quality SACD layer because of copy protection issues. The CD layer can be played via a coaxial or optical digital connection. Some SACD players permit a single digital connection (sometimes called iLink) between the player and the receiver, which eliminates the need for analog connections.
