1. The Compact Disc (CD)

2. The DVD Format - general

3. The DVD Audio

4. The Surround Sound Format

5. DTS (Digital Theatre System) and Dolby Digital

6. 24 Bit Format - The Ultimate

7. The Multiformat Device

8. Mini Disc and DAT (Digital Audio Tape)

9. Wave Correction

10. Declicker, Decrackler, Denoiser and Noise Print

11. Stereo Expand

12. Room Simulation

13. Spectral Cleaning

14. Reference Frequency Print

15. Pseudo Stereo

1. The Compact Disc (CD)

Since its introduction at the beginning of the 80s the CD has become the standard medium for digital audio recordings. This is unlikely to significantly change in the coming years.

The SACD (Super Audio CD) is however waiting in the wings as the CD's successor. With the introduction of the hybrid SACD, which carries both a standard CD and a high resolution 24 bit track, we could see a considerable boom in this medium.

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2. The DVD Format - general

The DVD was primarily developed for the film industry. It was designed to replace the VHS video cassette format. This it achieved with remarkable speed and success, with early sales exceeding even those of early CDs. It is then no surprise that the music industry's attention has been drawn to the potentials of this medium. Recordings of live concerts and other music productions are increasingly found on DVD.

The sound recordings on DVD are, however, often compressed because highest priority is given to the picture quality. To find out more, please read the entry "DTS and Dolby Digital".

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3. The DVD Audio

Alongside the SACD, the DVD Audio is also capable of reproducing high-resolution 24 bit sound. On a DVD Audio there is no video material. (Under certain conditions single titles can however be provided with visual material.) As a result DVD Audio is used to reproduce the highest possible musical quality.

To the disappointment of many consumers, DVD Audios are incompatible with many standard DVD players.

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4. The Surround Sound Format

The introduction of the DVD quickly brought with it the the surround sound format. This format allows filmakers to reproduce realist soundscapes with a variety of spatial effects. This technology can also be used by musicians in order to create a convincing sense of particular spatial environments. For example, the listener can experience the recording as if he/she were in a concert hall.

With surround sound there are a number of possibilities of configuring the loudspeaker system. Some sound engineers exhaust the full 5.1 potential, whilst others choose to restrict themselves to a 4.0 or 2/2 mix (2 front speakers/ 2 rear speakers). We have decided to use the second option (2/2 mix) as this corresponds more closely to the standards of vintage recordings.

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5. DTS (Digital Theatre System) and Dolby Digital

As previously mentioned, both DTS and Dolby Digital technologies are principally used for film. All the same, the music industry does make use of these.

Although both formats employ compressed music formats the sound spectrum is outstanding. The many music titles already available in DTS or Dolby Digital impressively demonstrate this.

We also offer these formats as they are currently the industry standard for all sound production on DVD Video.

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6. 24 Bit Format - The Ultimate

The 24 bit format is currently the premium sound reproduction format. Fans of 24 bit speak of the sound being fuller and warmer, somewhat similar to analogue recordings. In comparison, many analogue fans, quite rightly, criticize standard CD sound as being sometimes static and sterile.

The problem with 24 bit is that this format can only be played on DVD-Audio devices. The newest generation of DVD Video-Players can indeed reproduce 24 bit signals but, of course, only when this has been recorded on a DVD Video Disc.

CD Players do not support the 24 bit format. This may lead to some confusion as more and more CDs advertise themselves as 24 bit recordings. This is however misleading. The truth is that the audio has been recorded with 24 bit technology but on the CD there is only a 16 bit/ 44,1 khz Audiostream. 16 bit is the established standard for CD production. In fact a 24 bit stream simply wouldn't fit on a CD.

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7. The Multiformat Device

Given the confusing multiplicity of audio devices on the market, the audio industry has had to react quickly in order to stop sinking sales.

Therefore multi-format devices have begun to appear in recent years. Initially prohibitively expensive (over 2000 euros) these devices have in the meantime become much more affordable. The consumer need no longer be restricted to one particular format as the newest devices support all formats. These range from MP3 to high-resolution SACD. Indeed these devices can often also play back photo or computer typical formats.

Almost all major manufacturers offer these devices in a variety of price ranges.

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8. Mini Disc and DAT (Digital Audio Tape)

Mini Disc and DAT no longer play a significant role in the audio sector. It was hoped that the Mini Disc would supersede the cassette, however the increasing popularity of the MP3 has largely put paid to these ambitions. Very few major manufacturers now concern themselves with the Mini Disc. The same is true for DAT (Digital Audio Tape). Even as DAT was introduced it showed itself to be something of a problem child. DAT players were far too expensive and it was clear that the CD would be the medium of the future. Today DAT machines are almost exclusively used in studios and even here the technology has to a large extent been superseded.

Nevertheless, we do continue to offer this format on request.

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9. Wave Correction

Audio signals are represented in so-called "Waves" (wave-lines). Noise or interference are represented by intense, sharp amplitudes and irregular characteristics. (Diagram 1)

During "Wave Correction" these anomalies are localized and subsequently automatically corrected. (Diagram 2)

Diagram 1 (left): Typical image of interference

Diagram 2 (right): The wave-line after wave correction

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10. Declicker, Decrackler, Denoiser and Noise Print

These are the classic noise removers - here, however, in their professional form.

The Declicker is primarily employed to remove very intensive noises, for example the cracking noise often heard on vinyl. The Decrackler on the other hand, removes permanent background noises which are, for example, often caused by fixed dust bridging the grooves on vinyl. The Denoiser reduces the recording's root noises - a process which must be carefully analyzed and implemented. This is helped through the use of so-called Noise Prints

Diagram 1: Declicker, Decrackler

11. Stereo Expand

This is a typical sound-improvement tool. The stereo spectrum shown in diagram 1 finds itself far too much in the middle of the spectrum. This is often the case with analogue recordings. Therefore the stereo spectrum needs to be newly aligned. A correctly aligned stereo spectrum can be seen in diagram 2.

12. Room Simulation

Room Simulation is, in moderation, almost exclusively applied to extremely dull, muffled sounding recordings.

Here it is not possible to thoroughly explain this technology because of its complexity.

Those who would like to find out more should click here for more information regarding Convolution Technology.

Diagram 1: Room Simulation Mixer

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13. Spectral Cleaning

Many of you will no doubt ask yourselves whether or not Spectral Cleaning is really necessary and if so, why is it so expensive.

Because the standard professional restoration process produces such excellent results, "Spectral Cleaning" becomes not entirely necessary. However for thoroughgoing clarity this process is without question the absolute highlight at the end of the restoration procedure.

But how much does it cost?

Given that the complete process must be manually undertaken the question could be: "How is it possible that this process can be done so inexpensively?" After all, one audio minute costs only 50 cents (Euro)!

The post-processing of a normal LP is extremely time consuming. Depending on the degree of distortion in the recording, this process can under certain conditions demand many hours of work. However, in order to remain within a fair price range we calculate this service according to a 15 minute tariff.

Before you decide to make use of this service, you should first of all ask yourself the following questions:

• Do you have recordings for which you will only accept uncompromising audio quality?
  Audio purists will probably answer this question with, "all my recordings must be of an uncompromisingly high quality." Therefore we would like to help you with your decision, as the Spectral Cleaning process is often unnecessary. During the Standard Restoration Process we can quickly ascertain the extent of the damage to your recording and then personally discuss our estimate of the necessity of Spectral Cleaning with you. Afterwards you will be in a position to decide whether or not this service is of benefit to you.
  
  
• Are my recordings already in the "Carat 24" data bank?
  At the moment this is only the case for devotees of brass band music. However in the coming months this will dramatically change. Every month we will be posting an update on our website.
  
  The Advantage: Carat 24 is producing a number of first-class recordings for future production on SACD, HD-DVD /Blue-Ray Disc consistent with the highest technical standards. This means that both the Standard Restoration processes and in addition Spectral Cleaning are employed to create a recording of outstanding quality.

Spectral Cleaning counts as one of the most fascinating aspects of the restoration process and leads to astonishing results. Many music lovers can hardly believe that such results are possible. Music purists will certainly be among those who choose this procedure in order to experience their vintage recordings anew.
If you have any further questions regarding this subject, please click here.

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14. Reference Frequency Print

This is a highly specialized and intricate sound-improvement process. First of all a "Reference Frequency Print" is compiled. This is then presented in the form of a frequency curve with which the vintage recording can be individually optimized. This is achieved by using a FFT Filter 1024 Frequency Band which undertakes the fine adjustments. Sound refinement of the truly distinctive kind.

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15. Pseudo Stereo.

It is also possible to convert a mono into a stereo recording. The process involves converting the mono signal into a spatial signal. However, it must be remembered that this is pseudo stereo. Despite this, the end result is remarkable close to stereo and improves on the mono recording immeasurably.

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