The RIAA curve was introduced to allow LP's to be recorded with a fairly constant groove width by engraving them with reduced bass signal and increased treble signal. Lower frequency signals have a larger groove width requirement and without this correction there would be less playback time and higher distortion levels due to cartridge tracking problems. At the treble end the increased level during recording results in an improved signal/noise ratio when playback occurs. So on recording the bass signal is reduced and the treble signal increased, on playback the opposite correction is applied. On the other hand, audio CD's are produced to the Philips/Sony "Red Book" standard and this is so that any CD can be "read" by any CD player. The data is written in Constant Linear Velocity format. This has so many blocks per second, each block being divided into so many frames. These frames are encoded using EFM (eight to fourteen modulation) and use CIRC (cross interleaved reed solomon code) for error detection and correction. Hope this helps? Regards, Richard at www.vantageaudio.com
