There are two methods one could use to get production run copies of a Compact Disc - duplication and replication. From an end user perspective, there is virtually no difference between the two. Both methods are capable of creating high quality digital sound (or video, or programs, etc.) but to a computer, the products are different.

The Replication Process

To begin manufacturing Compact Discs from scratch, a digitized sample of the information to be printed on each CD must be very carefully scrutinized for any data corruption. Once the data is verified, a glass master is produced. The quality of the glass master is the true indicator of how well the final product will turn out. From the glass master, a stamper is created that is used to create the new CDs.

For each new step in the manufacturing process, the accuracy and precision of the data transfer is monitored very closely in an effort to make sure that every disc is a perfect clone of the original. After molding, the disc receives a micro thin aluminum layer to reflect the laser from the player back to the machine, and a layer of lacquer to protect the data before being printed or labeled with the data contents. Once the verification process is complete, the disc is off to packaging and shipping.

The Duplication Method

You have probably duplicated all or part of a CD, but it is more often known as "burning" a CD. The process is similar in industrial applications, except on a much more massive scale. Instead of your single drive in a single tower, a production duplication facility has hundreds of towers-each with numerous burning drives- linked together to create hundreds of copies at a time. After the data is verified against the Master Data, the process is over.

Replication Advantages and Disadvantages

For the most part, replicating discs is the cheaper method when manufacturing a large quantity of CDs. There are also more labeling options when you choose the replication method. Replication is best for high volume runs, and many facilities are equipped to automatically assemble the finished discs into jewel cases or sleeves. The lead time is a little longer on production machines, however, so with moderately sized orders you can expect it to take a week or so for the final product to be delivered while it may take just a few days with the duplication process. Most companies will require a minimum of 1,000 discs or more per order.

Pros/Cons of Duplication

On the upside, duplication runs usually don't take more than two or three days even for a run up to 5,000 units. Printing your own labels can be a big cost saver over prepress charges that a replicator might charge. However, the cost for each disc is slightly higher, and the small run nature of most of those facilities makes packaging the media a hand assembly process, which can be more costly for the same service a replicator provides. Additionally, CD-Rs used for duplication are vulnerable to direct sunlight which can potentially make a CD unreadable.

Is There Any Real Difference?

The process of duplication always involves a CD-R or CD-RW, while replication results in either a CD-ROM or CD-Audio. Duplication is what one does when he copies one disc to another disc with a computer. The information or data is sequentially 'burned' to the disc. Replication is reminiscent of the manufacture of vinyl records which involves a stamper that adds the data to the disc by stamping.

CD Duplication and Replication results are very similar. Because they extract the original information the same way, the end products perform very similarly. The main visual difference will be in the label, whether they are printed or screened in. The real difference is the need that the client has: for large runs that aren't rushed, replication is probably the best bet, but if you need the discs quickly or have fewer discs duplication is the way to go.