It took some 20 years before CD duplication methods became efficient and cost-effective. From a single CD to thousands, better tools and devices have made it possible for anyone to duplicate CDs even in the comforts of their own homes. The end products are not too shabby, either. CDs duplicated using modern software and hardware can boast of top quality and reliability.

Years ago, CDs came mainly as readable discs but as more and more consumers began clamoring for the kind of quality usually only available in digital recordings, manufacturers began producing CDs that could be encoded easily. Called CD-Rs or CD-Recordable discs, these discs made it possible for anyone who can operate a computer to perform CD duplications.

What CD duplication means

CD duplication is, put simply, photocopying, since light (laser) is being used to produce a duplicate. Imagine taking a master disc and making copies of it in a short time. What you have is a number of CDs which are exact replicas of the master, containing the exact files and data that the master disc has.

What you need

For starters, you will need a reliable computer, a CD-writer or burner and a music- or data-management software. Depending on what kind of files you will be copying, you can choose 'data CD' or 'music CD'. Most softwares will also allow you to choose which speed you want to use to burn the CD with. While faster speeds allow you to produce duplicates within a short time, slower speeds are less likely to produce errors.

What a CD burner does

A CD burner essentially functions as a photocopier. It is either a device that's already built in to the PC or an external writable drive. These days, desktop and notebook computers already come with CD drives or burners as standards. Even music enthusiasts are hooking a separate CD burner to their audio and stereo systems to facilitate faster duplication.

The CD burner uses a moving laser much like a regular CD player, except that it not only has a 'read laser', it also has a 'write laser'. The write laser interacts differently with the blank disc by producing a stronger light to change the disc's surface and thus alter it.

How CD duplication is done

When people say they 'burn' CDs, they mean copying data from a master source ? a hard disc, a floppy disc or another CD ? to a blank CD. A blank CD is either a CD-R or a CD-RW or re-writable. A CD-R will allow you to copy data on it but not change it. Whatever data you have on the disc will remain unchanged; you cannot make modifications nor delete anything. With a CD-RW, however, you can erase data and copy over and over again.

A blank CD has a flat, smooth surface, made of a reflective metal layer. Another layer underneath this reflective metal is made of photosensitive dye. This dye is translucent when the CD is not yet encoded. But when the CD-writer begins to 'burn' data onto the disc, the dye later is heated using a particular frequency. This is where the dye layer turns opaque and this time, will not allow light to pass through.

What the blank CD now has is no longer a smooth, flat surface but a surface that has microscopically darker areas which contain a digital pattern 'burned' into them. The altered surface now contains data copied from the master source.

Speed matters

The rate at which CDs are duplicated will depend greatly on several things: the amount of data on the disc, the speed of the copy disc, the speed of the connection between your PC and CD burner and the speed of the CD burner itself. At a 1x speed for example, the disc will spin at the same rate it does when you put it in a CD player. So if you have a CD that contains 120 minutes of recording, you will be able to duplicate that CD in 120 minutes as well.