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  DVD-A and SACD. Date Posted 27/08/2001.

The CD has been around for nearly twenty years, and was designed to be the final format, which would offer the best quality sound possible. However, many people still complain that vinyl sounds better. Because of these criticisms of CD, it was not surprising that various hi-fi manufacturers have developed new formats, to address these concerns. Another major motivation has been the fact that Sony and Philips (who invented the CD) are going to lose out on commission from CD patents in a few years.

Sony have Super Audio CD. It uses a new system to record audio DSM with a frequency of over 100 kHz - 2.82 MHz. In the Panasonic corner there is DVD Audio which works at 24 bit 96 kHz recording in the traditional PCM format, which virtually all digitally recorded audio uses. Both offer 5 channel audio, as opposed to stereo (although not every disc will offer a 5 channel mix). At first though only SACD stereo CDs were released, however, now 5 channel SACDs are appearing on the market. It must be noted though that DVD-V also offers multichannel sound, usually encoded in a compressed format like Dolby Digital or DTS, which being compressed won't sound as good as DVD-A, SACD or CD for that matter. DVD-A, SACD and CD are uncompressed formats.

Let's first look at the case for DVD-A. Our ears have an approximate range of 20 Hz to 20 kHz. Although we can't hear sounds of higher frequency, sounds recorded at 96 kHz will be a more accurate representation of the sound than those recorded at 20 kHz. Also being a 24 bit format, the you will have a better range of dynamics, something better for classical music rather than pop music (which is often about the same volume throughout a track). Sound is a wave, and when it is recorded using PCM it is approximated using a process called quantization, so if you were to zoom in it would like a jagged representation of the actual wave, the higher the bit rate and frequency the smoother the wave would look and consequently the more accurate it would be to the original recording. Most sound waves are smooth (except some synthesised sounds) and so this process of quantization is very important, and is performed by an analogue to digital convertor. Basically DVD-A is like CD but offers a more accurate way of quantization. The idea of converting data to a digital format (rather than leaving it in an analogue format, like cassette or vinyl), is that it will sound virtually identical when played back and won't degrade as much over time. Also copies are 100% identical. SACD uses a new technology called DSD, which has a different form of of converting audio into a digital form, which does not need so many filters as DVD-A or CD to be converted into digital. The 2.82 MHz is incredibly high too.

On the face of it both formats are far better than CDs, which store audio at what must seem a pedestrian 16 bit 44 kHz. Both DVD-A discs and Super Audio CD discs look like CDs. Consequently both DVD-A and Super Audio CD players can also play CDs (some play DVD-Videos too). Unfortunately, given that each manufacturer is pushing their format, they are in no will to compromise, which probably explains the lack of "Super machine" which can play both DVD-A and Super Audio CD. In addition, many Super Audio CD's have an additional layer (but not all!), so they can work on ordinary CD players. Obviously, though it will not sound as good as if played on a Super Audio CD. DVD-A does not work in any CD player. Only certain more expensive DVD-V players can play DVD-A, so before buying a DVD-V make sure you check it also works with DVD-A.

I have not heard either DVD-A or Super Audio CD so I cannot say which is better. Audiophiles are still largely undecided on the question of DVD-A, Super Audio CD, CD or vinyl. However, there is now a movement towards to SACD, which some say sounds better than DVD-A because of DVD-A's copy protection system and the new DSD system. This DVD-A system uses an analogue watermark, which is supposed to be unaudible, but some say degrades the sound. At the end of the day the only way to find out would be to listen to an identical recording of DVD-A and SACD side by side.