DSD: the recording technology behind SA-CD

Super Audio CD uses a new and radically different technology called Direct Stream Digital (DSD) to convert music into a digital signal that can be stored on a disc. Compared to the traditional PCM method (the technology used for CD), DSD offers a much higher resolution by following more closely the original wave form of music. With a frequency response of over 100kHz and a dynamic range over 120dB across the audible frequency range – some 64 times higher resolution then CD – Super Audio CD offers music reproduction that reveals details you just can’t hear on a normal CD.

The Direct Stream Digital™ pulse train “looks” remarkably like the analog waveform it represents. More pulses point up as the wave goes positive and down as the wave goes negative.

Simon Heyworth, Super Audio Mastering in Devon (United Kingdom):

“For producers hearing a DSD master for the first time, I believe it’s important that they hear a distinct difference – a master that has more space. DSD is just so much better than PCM. Some producers are completely shocked and blown away. DSD is not like other digital formats. It has a musicality, which portrays in a real sense musicians playing together.”

1 Bit Technology

In audio, simpler is better. And the Direct Stream Digital™ process (bottom) is far simpler than the PCM digital process (top).

DSD uses 1-bit delta-sigma modulation and a sampling frequency 64x higher than CD. Super Audio CD recordings don’t have to subject the original sound waves to the decimation and interpolation stages associated with PCM. Hence DSD sound reproduction is much more natural and accurate in staging, and is often favourably compared with the best analogue recordings, but without the hiss and other artefacts that are also associated with analogue recordings.

Ronald Prent, Galaxy Studio’s at Mol (Belgium):

“DSD gives the engineer unlimited dynamic range, so you can be really wild with the sound images that you create. Also, in acoustic recordings, you are afforded so much more freedom, experimenting with multi-channel set-ups.”

Multi-channel Surround Music

The introduction of DVD video has spawned huge interest in the surround sound experience. With Super Audio CD, music too can be mixed to 5.1 multi-channel surround sound (instead of just stereo left and right).

The DSD signal can be delivered in up to 6 separate channels (front left, center, front right, left rear, right rear + subwoofer) making it possible to maintain extremely high resolution across all speakers without even the slightest sacrifice in sound quality.

Jens Kuphal, Nucleus studio in Berlin (Germany):

“Obviously, the much higher sound quality gives you a much better feeling over CD productions. Being able to put down and replay 5.1 mixes of such high standard invites us to push our creative boundaries on a daily basis. From a creative point of view, Super Audio CD provides the possibility to join the artist in the studio. The whole mood is captured and preserved on a sound-carrier.”

Not all SA-CD’s contain a multi-channel mix.

The decision to mix or remix recordings for 5.1 surround is based on the choice of the artist/ record label and the kind of original source material that is available. In some cases, for instance with the Rolling Stones Remastered series, the music will benefit from the higher resolution in Stereo DSD, but not allow for the creation of the full Surround Sound reproduction.

The Super Audio CD Disc

Super Audio CD data is stored on the same physical carrier as DVD-Video. Making use of this highly successful consumer product brings many advantages, such as the use of mass produced components and making combination players which play both SA-CD and DVD-V.

This silver disc can store more than seven times the information of the standard CD, providing up to 74 minutes of full resolution surround music – the same duration as a stereo CD. A Super Audio CD has two distinct mixes, one for stereo and one for multi-channel.

Hybrid Disc

Furthermore, there is an option to add a separate CD layer to the DVD disc: the so called ‘Hybrid Super Audio CD. Hybrid SA-CD’s can be played back on virtually all CD drives and players as well as all standard DVD-Video systems. This makes Super Audio CD’s compatible with all 11 billion CD and DVD players used around the world.

4 types of Discs

There are four different SA-CD configurations commercially available to record companies:

Hybrid Discs

The vast majority of SA-CD’s introduced to the market today are hybrid type, containing the CD layer. This disc plays on a CD and DVD player, at CD quality.

Single Layer Discs

There are also SA-CDs without the CD layer, so-called single layer discs. These can not be played on a standard CD player. The advantage is that this is an entirely secure digital carrier.

Both the hybrid and single layer SA-CD can be released as a stereo-only album, or as a stereo plus surround album.

4 types of Discs

So to recap: stereo or surround is entirely a choice of the releasing company, as is the choice to produce hybrid or single layer discs.

Note: it is strongly recommended not to release surround only SA-CDs (i.e. there is no stereo DSD mix), as a large population of SA-CD enthusiasts still listen in stereo only. Releasing an album on SA-CD surround only would deny access to this market, which can only play back the album in stereo DSD.

The sleeve artwork of any SA-CD will explain the disc’s contents.

Content Protection

Super Audio CD offers the world’s most secure digital carrier, utilising a combination of physical and electronic protection barriers. These are layered around the audio content in five independent layers, including a combination of mechanical and encryption-based protection systems that cannot be broken using any current hacking technique.

  The end result is that when you buy a Super Audio CD in a music store, you can be confident that it’s the genuine article and not an illegal, inferior quality copy.

  The CD layer on the hybrid disc is similar to a conventional CD in that it’s open to copying onto other carriers for home use.

Just push Play

A hybrid Super Audio CD will play in all CD and DVD players, at CD quality. So if you want to be ready for the future but don’t have a SA-CD player yet, just start buying your albums as hybrid SA-CDs. Go ahead and buy the new Sting ‘Sacred Love’ album on SA-CD: enjoy the CD now and the SA-CD later.

To listen to the album in highest resolution and surround sound, you need a player with SA-CD functionality and a compatible surround sound speaker set up. To find out more about SA-CD hardware, please check out our ‘player’ section.