MP3 Player buying guide

Learn more about MP3 players

First, theres the question of design. A player can have every feature in the world, but if the design doesnt match your lifestyle or if the interface is impenetrable, you still wont enjoy it. Youll want to look closely at performance; sound quality and battery life can make or break a player, especially if you travel a lot or have the so-called golden ears of an audiophile.

Before you start checking out specific models, you should have a basic understanding of the types of MP3 players available.

Most likely, a high-capacity, hard-drive-based player can accommodate every song youve ever purchased. Hard drives run from 10GB on up, and large players such as the 60GB Apple iPod can hold around 17,000 songs, assuming an average file size of 3.5MB per tune.

Straddling the line between full-size hard drive-based MP3 players and compact, flash-based players, micro hard-drive models aim to give you the best of both worlds by using miniature hard drives (about 1 inch or less in diameter) with capacities of up to 8GB. Players such as the Creative Zen Micro Photo cant store as much music as a 30GB Cowon iAudio X5L, but they feel a lot lighter in the pocket.

The original MP3 player design, flash-based players have no moving parts and are known for their shockproof operation and ultracompact dimensions. Devices range in capacity from 32MB to 6GB, though most new players dont go below 512MB... SanDisks MP3 line, for example, includes exclusively flash-based players. Read more

Syncing high-def music with digital generation
Elvis Presley would judge the recording quality of his songs by whether the sound "moved him or not," says music producer Elliot Mazer.

After four decades producing some of the recording industrys biggest artists--everyone from Janis Joplin to Switchfoot--Mazer has developed his own test. He asks himself: "Can you enjoy the music when its playing at a low level?"

In the digital age, too often the answer is no. Much is lost when cramming Joplins booming vocals or the rich guitar play of Pete Townshend or Jimi Hendrix into tiny digital files, Mazer says.

The rise of digital music players has made it easier to cart hundreds of songs around but has done little to improve listening experience, say music aficionados. A popular misconception is that digital music has to produce sound quality inferior to compact discs.

Not so, say companies such as MusicGiants and Sonos, which offer audiophiles a chance to listen to digital music whose sound quality is every bit as good as that available on CDs.

MusicGiants, which launched last September, is the only download site that sells high-definition music from all the major labels. Incline Village, Nev.-based MusicGiants sells songs on the Windows Lossless format, which means that the company offers music at a bit rate of 470 to 1,100 kilobits per second. Most songs downloaded off the Web are at 128 Kbps, says Scott Bahneman, MusicGiants founder and CEO.

How does an MP3 player work?
At their most basic level, digital music such as MP3s looks a lot like any other computer data file: a long series of 1s and 0s. In order to turn an analog signal (such as one picked up by a standard microphone) into a digital stream, ADC (analog-to-digital converter) software measures the signal at a regular interval to find the sampling rate. These samples, if measured close enough together, form a near-exact representation of the analog signal so as to approximate the transmission using 1s and 0s that computers and MP3 players can read.

Each second of true CD-quality sound takes up more than 1.3MB of disk space, which is why file-compression technology is essential to digital audio, especially portable audio. Using principles of psychoacoustics (how the brain perceives sound) and perceptual coding (eliminating imperceptible sounds), engineers develop algorithms, called codecs (compression decompression), that compress songs into the smallest possible sizes with minimal loss of quality. The sound depends on two factors: the quality of this compression algorithm and the bit rate at which the song is encoded, measured in Kbps.

When you play a digital file, you essentially reverse the analog-to-digital process. A digital audio device, such as an MP3 player or a computer sound card, uses a DAC (digital-to-analog converter) to turn the 1s and 0s back into an analog signal that can then be amplified and broadcast over headphones or speakers. The sound depends on the attributes and quality of the digital file, the DAC chip in the player, the amount of distortion and hiss added by interference from the devices other circuitry, and the audio output level of your headphones or speakers.

When a digital device plays music that has been compressed by a codec, software on its chip (called firmware) applies the codec to decode the file, then sends the decompressed 1s and 0s to the DAC.

The first format or codec to gain widespread acceptance was MP3, but there are now a variety of players on the market that support AAC, WMA, OGG, and other formats. This table will help you sort out the alphabet soup and determine which codecs you need in an MP3 player. Read more