The Analogue Compact Disc (ACD), the perfect sound medium

It is known by many audiophiles and high quality sound lovers that the Vinyl Disc has probably the best sound among all the reproduction medium. I do not want to get into this tribute, instead I will try to get into more technical issues that prove this belief to the vinyl disc. I consider the fact that the vinyl disc (and the bad sounding analogue tape) is the only medium in which music is written onto it in an analogue way.

Our world is analogue, we listen in an analogue way, the perfect sound is no other than the non-D/A-converted analogue sound! The analogue reproduced waveform out of the best D/A converter you can ever find, will never be as perfect as the waveform generated by a hypothetical perfect pure analogue source.  The vinyl disc is the only analogue music medium that provides good sound with relatively high dynamic range and at the same time it overcomes the rewinding problems of the audio tape. But we have not solved the problem of achieving a perfect sound yet. Despite of the analogue nature, vinyl discs have some disadvantages that made them progressively disappear.


1. Vinyl discs are big and heavy - CDs are small and lightweight.

Yes in our world size does matter. We always like things to get smaller and lighter because this makes them more comfortable and easy to use.


2. Vinyl discs are progressively destroyed - CDs are not.

Here I consider only the wear from the way that the disc is played. The gramophone head (needle) is continuously rubbing the vinyl disc causing it to progressively get destroyed. Every time you play your favorite vinyl disc it gets destroyed more and more. The laser turnable that uses a laser beam to read the disc instead of a needle can eliminate this though. Well, CDs have also a lifetime but it is much much greater than the lifetime of a vinyl disc.


3. Vinyl discs are more susceptible to bad use than CDs.

Big and bulky discs that are stored in paper cases are more susceptible to damage due to scratches. From the other hand small and lightweight discs that are stored in a hard case cannot be easily damaged. Also, because of the strong error correction algorithms used on CDs, a scratch on a CD may not cause any problem. A scratch on a vinyl disc from the other hand will always degrade the sound quality and the disc may be totally damaged.


4. Vinyl discs cost more than CDs

Apart from the production procedure, a vinyl disc requires more material than a CD in order to be made and this results in a greater cost.


5. No compression and error correction on vinyl discs

Analogue signals are composed of infinite states in relation to digital signals that are composed of two states, zero or one. Because of this, we cannot perform error correction and compression in an analogue waveform. The sound is written in an analogue way on the vinyl disc (and it is played in real time) and this leaves no chance for error correction and compression.


The Analogue Compact Disc (ACD) - a better approach.

Our technology has become great the last decades and things have become smaller and smaller and more sophisticated. Also, new synthetic materials have been found. I was thinking "Why we could not make use of this technology and achieve all the advantages of the analogue reproduction in music whereas at the same time eliminate the disadvantages of the vinyl disc?". We already have a great medium available, the CD. Let's use this known to everyone medium and give it an analogue nature. This is how the Analogue Compact Disc is born!

My approach is to use the polycarbonate CD and find a way of print onto it, the representation of the actual waveform and not just bits, as in ordinary CDs. Then, there must be found a way to read this waveform representation and convert it directly and in real time to music, just like a phonograph player does, instead of performing D/A conversion. This ACD must be stored in its hard case before and after use and carefully handled, to avoid errors from dust and scratches. The greater care is the price you have to pay for the super high quality sound.

In fact the ACD must be a mixture of analogue and digital. The actual songs will be stored in an analogue waveform representation on the ACD but there must be a way to read the track information and position the head accordingly. In vinyl discs we do it manually by watching the disc spaces between tracks. In ACD this information could be written for example at the start of the disc. Then the head reads this information when the ACD is inserted and knows when each track starts and ends. The ACD can also store other information that way, like the song title etc.



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