Copyright Michael Karbo, Denmark, Europe.


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    Chapter 6. Better quality than a CD

    There are two parallel trends in the music market at the moment:

  • Mp3 and similar formats with compressed sound, which, all other things being equal, give a sound quality, which is worse than a CD.

  • Surround systems with DVD Audio and SACD with a much better quality than a CD.

    20 years’ ago I was myself a hi-fi fanatic and loudspeakers and stereo systems couldn’t be too big or sophisticated. Nowadays, I listen to a lot of mp3 files through headphones or good computer loudspeakers – and I have got used to their form for sound quality. In the kitchen, I have even accepted a worse quality of sound from a little transistor radio.

    My point is, that our hearing is a rather subjective arrangement, which easily gets used to its conditions and surroundings. Mp3 is, for example, without doubt a step back with regard to quality but because the operation and flexibility of music systems has been much improved with mp3s, then we accept these conditions. Another thing is that the music’s artistic qualities can often be enjoyed – irrespective of whether the source is analog or digital, of top quality or medium quality.

    There is, however, no doubt that a big surround system can give a much better sound reproduction today than that we have been used to with normal CD stereo players. Great developments are occurring in this area and it will be very interesting to follow them in the coming years.

    Analog or digital sound

    Since 1982 the ”standard” for digital mu­sic recording has been a sampling of 44,1 kHz and a resolution of 16 bits. This ensures a full tone range up to 20.000 Hz. Most ”normal” users agree, that the sound quality of a CD is all right and ”high fidelity”. But it wasn’t like that in the beginning; when CDs were introduced, there were a lot of people who didn’t like the sound.

    I can remember some years’ ago, when I first heard my favourite jazz record, Miles Davis’ ”Kind of Blue”, on a CD. It was a record I had heard hundreds of times before on a good hi-fi systems, and the CD recording was clearly a disappointment – there wasn’t any of the ”warmth”, ”depth” and ”roundness” in the recording, I knew so well.

    If you are a connoisseur of music and listen to it and if you are critical, a CD does not give top sound quality; the sound is a little cold and dull. Which is why there are still so many small companies, that produce analog record players and why music is still published on vinyl discs.

    Figure 27. Analog record player. A technology, which many still prefer to CD media.

    Better digital sound

    The deficiency of ”musical quality” in CD recordings has proved to be not so much the digitisation but rather that it is done badly. Of course, it is possible that it is just a question of bad recordings – which it often is.

    The sampling is simply too crude in a normal CD quality. But with the development of more powerful computers with DSPs (Digital Signal Processors), faster processors in general and improved media (such as DVD), it is possible today to create a digital sound with a much better quality than a few years ago.

    The music industry is aiming to introduce a digital sound with greatly improved sampling and 5.1 sound. There are two rival formats here, which have been marketed during the last couple of years:

  • Sony and Philips SACD (Super Audio CD)

  • The Japanese DVD-A (DVD-Audio).

    In both cases, it has to do with CD/DVD-like discs with a diameter of 12 cm, which are sold in music shops. The only difference is that they have a much larger capacity and can, therefore, store music recordings of a completely different quality and with a lot more dynamics and depth perspective. Both formats are described later in this chapter.

    Finally, we can see a similar development with sound cards for computers, which have undergone a vehement technological development. The modern top models from, for example, Creative Labs can work with PCM sound data in a 24-bit resolution and with both 96 and 192 kHz sampling frequencies.

    These sound cards can, in fact, work as a nucleus in a cheap digital sound studio to the advantage of amateur musicians.

    Figure 28. Sampling with 96 kHz using a standard computer sound card.

    SACD

    In 1999 Sony and Philips joined forces again to further develop the CD media. The result was the new SACD media, Super Audio CD.

    An SACD is, as mentioned earlier, a disc, which looks exactly like a normal CD. It can, however, only be used in a special SACD player, because technologically SACD is very different from standard CDs. The disc itself contains six times as much data (4,7 GB) as a normal audio CD. It can also deal with multi-channel sound with up to 6 channels and several other sorts of data.

    SACD media contains nearly five times as much data per minute of music, which makes it possible to give an even better sound quality. The big difference is in the sampling. Where a traditional CD is ”encoded” with a 16 bit PCM sampling with 44,1 kHz, then the SACD media works with a completely different 1 bit DDS code, which takes place with 2,8224 MHz. All in all, this gives four times as many samplings per second and, thus, a much better ”resolution” of the music.

    DDS stands for Direct Digital Stream, which is a system which should be much superior to traditional PCM coding. Among other things, the use of a number of filters necessary for PCM coding, but which remove subtle sound nuances, is avoided. Sony asserts that SACD recordings are unbelievably close to the original analog sound.

    There is a version with twice as much capacity (two layers of data). In the short term, SACD media is not meant to replace audio CDs, but rather as a “de luxe edition” for sound fanatics.

    Figure 29. Complete system with DVD video and SACD, in addition to an FM tuner and a powerful amplifier plus a set of high-end loudspeakers from Philips.

    DVD-Audio

    The rival format DVD-Audio has been developed by the companies Matsushita (consisting of Denon, Pana­­so­nic and Technics), Kenwood, Toshiba and JVC. In DVD-Audios the sound is PCM sampled just like with CDs. The difference lies in the sampling, which usually takes place with a frequency of 96 kHz and with 24-bit resolution (called 96/24).

    Furthermore DVD discs are made with lossless compression (MLP), which means that the sound’s data is internally compressed by a factor of 2; there can really be a lot of data on a DVD-A.

    Both the resolution and the sampling frequency can be varied, however, so you can in this way get an extremely flexible media, which can also include video recordings, etc. of superb quality.

    Which should I choose?

    It’s not smart having two rival formats like SACD and DVD-A on the market. The problem being, that record companies have to publish music in two formats, which is troublesome. It is also inconvenient for users, because they have to have special players for both formats. At the moment, it is difficult to say which one will be the ”winner”. To the advantage of DVDs, Audio discs will increasingly be built into the software of standard DVD players. On the other hand, both Sony and Philips are really investing enormously in SACD recordings, studio equipment, etc.

    Luckily, there are combiplayers, which can handle both formats; Yamaha, Denon, JVC and Pioneer can all provide such players (see Figure 30).

    Sony has seen to that SACD discs are compatible with standard CD players as a sort of hybrid disc, which has been encoded with a normal CD layer in addition to an SACD layer. This means that the disc can be played in normal CD players, the extra layer contains the music in a traditional CD version. Something like this is also used in DVD-A.

    The conclusion being that at the moment there isn’t a wide choice of DVD-A and SACD products and prices are high.

    The sound quality is much better; with six loudspeakers arranged around the listener (see Figure 54 on page 3), there is a completely different feeling of space and depth. When listening to a classical concert, you can, so to speak, hear each and every single instrument’s place quite clearly. The music industry sees great possibilities in the new media, which also have the advantage of being very difficult to copy …

    Figure 30. A combiplayer from Pioneer, which can handle all DVD formats plus SACD.

    You can see here a comparison of the rival sound formats:

     

     

    Audio CD

    SACD

    DVD-A

    Capacity

    650 MB

    4,7- 8,5 GB

    4,7- 8,5 -17 GB

    Number of channels

    2

    2-6

    2-6

    Music length

    80 min.

    110 min.

    70-260 min.

    Sampling

    44.1 kHz

    2.822,4 kHz

    Surround: 96 kHz Stereo: 192 kHz

    Resolution (quantization)

    16 bit

    1 bit

    16, 20, 24 bit

    Overtones

    22 kHz

    100 kHz

    96 kHz

    Dynamics

    96 dB

    120 dB

    Op til 144 dB

    Figure 31. Digital sound formats that compete for the favour of consumers.


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