The compact disc is a miracle of modern technology. Here are some facts:
- They are made principally of injection-moulded polycarbonate.
- The diameter is 120mm.
- They are 1.2mm thick.
- They contain up to 680 megabytes of data. This is the equivalent of 250,000double-sided leaves (500,000 pages) of A4 text (which would be 83 feet highand need 8 trees to make).
- The music on a CD is imprinted in the form of pits of varying length on aspiral track 3.52 miles (5.66 kilometres) long.
- There are approximately 16,000,000,000 pits 0.11 micro-metres deep.
- The largest pit dimension is 3.054 microns; the smallest is 0.833 microns.
- The width of the pits is half a micron -- which is the distance a human hairgrows in two minutes and a fingernail in seven minutes. It is 700 timessmaller than a pinprick.
- The space between tracks is 1.6 micro-metres.
Read by a red-light laser beam, the CD plays from the centre to the edge,rotating at a speed varying from 400 times a minute at the beginning to 250times a minute at the end. This is equivalent to flying round the earth oneinch above the surface, up to 400 times a minute, counting every blade ofgrass on the way.
Your CD is read by the laser beam and makes over 44,000 arithmeticalcalculations every second in at least two dimensions. It is adding upcolumns of numbers ('digits'). But many of the numbers are missing becausethere are thousands of errors on the average CD. Therefore thenumbers are added up laterally as well as vertically, enabling the CD-playerto fill in the missing numbers by cross-checking them. This is all quitenormal and is called 'error correction'.
FAULTY CDs
In proportion to the enormous quantities of CDs which are manufactured,faulty ones are extremely rare -- far far fewer than was the case withlong-playing vinyl discs.
We at Hyperion receive about 100 to 150 so-called `faulties' per year,returned from customers. In addition we receive a similar number of reportsof faulties (by phone, letter, email etc). That makes a total of about 300complaints a year. Of those, perhaps 3 only are found to be justified andthe discs in question truly faulty.
The 'fault' most commonly reported is failure to play -- usually one or twotracks, but sometimes the entire disc. This is one of the greatest mysteriesof CDs: Why does a certain disc fail to play on a particular machine?Frequently a customer complains that a particular CD 'won't play' or'jumps'. They usually say that they've never encountered the problem beforeand every other CD plays perfectly well on the same machine, therefore theremust be something wrong with the disc. Upon being advised to try the CD onanother machine they are usually nonplussed to find that it does in factplay perfectly satisfactorily, with nothing apparently wrong with it. Thispuzzling fact can lead to all sorts of strange cases. One disc was replacedfor a Hyperion customer no fewer than NINE TIMES. In every case thereplacement disc was tried, and found to be satisfactory, before being sent.They all refused to play except the ninth copy! And yet they were allidentical and from the same pressing run. And not a single complaint wasreceived from any of the other 15,000 people who had bought the same CD. OneHyperion artist was sent six copies of one of his CDs soon after issue."They're all faulty!" he afterwards phoned to say in great agitation. "Itwill have to be repressed." Yet copies had already gone to journalists, theradio stations and other people, and there had been no complaint. But herefused to believe that there was nothing wrong with the disc until he wastaken to my car and the whole disc was played through on the car CD-playerwith no trouble at all.
This phenomenon, for which nobody seems to have an explanation, is currentlybeing investigated by at least one CD factory.
It occasionally happens that a disc is found to contain the wrong music,although the label is correct. This can happen in a CD plant at theend/beginning of a run when stampers are changed in the press, out of syncwith the labelling machine. It is a human error and usually affects only oneor two copies, so if you find yourself with one you have been veryunfortunate. It will of course be replaced.
It is a sad fact that many of the CDs returned to us as faulty exhibit thecauses of the fault only too blatantly as finger-marks and other dubiousforeign matter of unknown origin. On one occasion marmalade was diagnosed.Many of the returned discs have obviously been maltreated and show not onlyfinger-marks but scratches and blobs and other bits of dirt.
The microscopic information on a compact disc should be respected and thedisc treated with care. Laser beams cannot pierce layers of human detritus.
WHAT TO DO IF YOU THINK YOU HAVE A FAULTY HYPERION CD
If it contains the wrong music but is otherwise OK (correct label, bookletetc) please notify us by letter, postcard, fax, phone or email (for therespective addresses please refer to our home page), and tell us what youthink the music might be ('a pop record', 'some organ music' or similarrough description). If you can, please tell us the matrix number stampedinto the shiny centre area of the disc. Do NOT return the disc to the shop.You may, if you like, return the disc to us (and we may ask you to), but ifyou do, PLEASE SEND JUST THE DISC, NOT THE ACCOMPANYING PRINTED MATTER.
If you find yourself with a disc which doesn't play properly, or not at all,TRY IT ON ANOTHER CD-PLAYER. If it still refuses to play then please let usknow, telling us the title and disc number, specifying precisely how itmisbehaves ('refuses to play track x', 'skips a lot', 'machine refuses toplay it altogether' etc). If you want to send it back to us please do so --but again, just the disc, not the accompanying material. From the number wewill be able to ascertain the factory where it was made.
A sizeable proportion of the CDs returned as faulty apparently havedifficulty playing only the last track or tracks. This is generally due toan inadequacy in the player which prevents it from playing some of thelonger CDs (75 minutes or more). Oddly enough this is often the case withsome of the more sophisticated CD players; more basic, primitive ones seemto be able to cope perfectly well with the discs. In any case the failing isin the players, not the discs.
If you do find it necessary to complain about a particular disc please alsoinclude details about your CD player: make, model number and age. Thefactories often ask for this information.
