Your boombox won’t play your CDs?

Question: My portable CD player has been stolen, so I am going to buy a new one. The old one wouldn’t play CDs I made on my CD-RW drive on my computer, and I want to be sure the new one will. What should I look for when I buy my new player? —V.B.

Answer: This technology can be pretty confusing, especially if you’re new to the world of digital music.

To research your question, I checked in with Shawn Conahan, Vice-President and Head of MP3 Mobile, at, and he filled me in on key issues surrounding the question.

In the world of CDs, there are three kinds of disks and two kinds of formats.

There are CDs that you buy from the store that have music already on them. These are audio CDs. There are also blank data CDs that can be “burned” (recorded on) by a special CD drive. These come in two formats. CD-R (also called CD-Recordable) disks can have data added to them once, they cannot be erased and re-recorded.

For that, you need a CD-RW (also called CD-ReWritable) disk. These disks can be written to by a CD burner, and then erased and reused.

CD-R and CD-RW disks can be formatted as either data or audio disks. When formatted as audio disks, a CD player sees them as any audio disk that you’d buy from the store.

When they are formatted as data disks, you can add any data files to them from your computer. If you add music files to a data disk, these files can be read by audio players that recognize data CDs (some do, some don’t—check your player).

MP3 is the most popular music file format, but some players will also read WAV files, older audio files created by Windows. Some players will also read files in WMA format, an audio format from Microsoft.

Creating data CDs with MP3 files on them is particularly useful because you can put about ten times more music on a data-formatted CD than on an audio-formatted CD.

An average four-minute song in an MP3 file format is about 4 megabytes in size. That means you can fit about 150 songs on a data CD.

If you burn an audio CD, you’ll be able to put 10 to 20 songs on it. To take advantage of this amazing feature, an audio player has to support data CDs specifically. The specifications on a CD player’s box say clearly whether this is the case or not. If it is, it will say the box is MP3 compatible. The features list in the player’s marketing material should also list whether it supports CD-R and/or CD-RW data disks. Some players will read MP3 files on a CD-R data CD, but not on a CD-RW disk.

The Radified Guide to Ripping & Encoding CD Audio has a good guide to recording music on CDs.

PC Guide also has a good reference site.