GOODSOUND!GoodSound! "How To" Archives

Published October 15, 2002

 

How to Choose Between a CD Player and a DVD Player

It seems as if it would be easy to decide whether you're better off owning a CD player or a DVD player. A person could easily assume that if you like Alfred Hitchcock more than Jimi Hendrix, you'd choose a DVD player. If you prefer R. Kelly to Grace Kelly, you'd get a CD player. However, it's not quite that simple in this abruptly changing techno world.

It's not hard to get the components together that'll make your listening experiences (and maybe your movie-watching experiences) as enjoyable as your budget will allow, but it does take a bit of time to gather some relatively uncomplicated information. We're going take a look at some differences and similarities between CD players and DVD players to make it easier to make that right choice.

First, let's get some of the obvious stuff out of the way. A DVD player can display a movie and whatever else comes stored on a DVD. It can also play your standard CDs, while a CD player is limited to playing only CDs (though a lot of new players can also play discs burned with MP3 files, CD-Rs, and CD-RWs -- DVD players can often play back all of these formats too).

DVDs and CDs: sharing the technology

The two formats have a lot in common. Both CD players and DVD players are equipped with lasers that read microscopic pits on the surfaces of the clear polycarbonate discs. The pits are incredibly small -- each is half-of-a-micron wide (a micron is a millionth of a meter) and 125-nanometers deep (a nanometer is a billionth of a meter). To put these tiny spaces into some perspective, think of them this way: You could put all of Carrot Top's talent in a single pit and still have room left over! (We admit to having a slight bias against the crimson-colored "comedian.") Another way to look at it: If you took the pits on a double-sided, double-layer DVD and stretched them out into a straight line, they would extend over seven miles.

The information tracks on both DVDs and CDs begin at the center of the discs and spiral outward toward the edge of the 4.8" discs. (Because the tiny tracks begin in the centers of the discs, CDs can be smaller than the size you normally get at the music store -- DVDs can be smaller too, but we've yet to see one anywhere.)

Both DVD players and CD players have incredibly precise lasers that read these minute tracks. Motors in the players spin both DVD and CD discs at between 200 and 500 rpm, while lens systems focus on the pits on the discs, as tracking mechanisms move the lasers so that they can follow the spiraling information tracks.

Advantage: DVD

Even though DVDs and CDs share basic technology, DVDs can store much more information than CDs. That extra information is what gives DVD its biggest advantage over CD: the capacity to store a movie (and more) on a single disc.

A DVD stores up to seven times as much information as a CD. Why? Because their methods of storing information differ. The track pitch on a DVD is 2.16 times smaller than on a CD -- meaning that the spiral-information is packed much more closely together on a DVD -- and the minimum length of a pit on a DVD is 2.08 times smaller. Also, CDs store lots of error-correcting information (repeated information on the disc that helps the CD player reduce the possibility of reading errors), whereas DVDs are designed to have less of this sort of repetitive info, increasing the space available on the disc.

One of the biggest data-capacity advantages a DVD has over a CD is in its layers. DVDs are like information sandwiches, with layers of digital information pressed between thin slices of plastic and even thinner sheets of aluminum and/or semi-reflective gold. The laser on a DVD player will read from the center of the disc to its edge and then switch its focus to a second layer of information stored beneath the first, which spirals inward from the outside edge of the disc back to the inside.

Even with all of that storage space available, movies and the extras included on DVDs devour it quickly, which is why the format also employs a compression technology known as MPEG-2 (MPEG stands for Moving Picture Experts Group). CDs employ MPEG-1 compression technology and MP3s use, naturally enough, MPEG-3. Basically, each level of this compression involves more pinching of info than its predecessor. The digital information compressed via MPEG-2 on a DVD is squeezed 1.6 times as much as the info stored on your CDs, for instance, and an MP3 file of a song is crushed to one-tenth the size of the identical tune on a CD.

Advantage: CD

While advocates of DVD tout the joys of being able to watch a movie and listen to music with a single player, proponents of CD aren't without ammunition in a debate over which technology is preferred for listening to music. (There's no doubt about which one is better for watching movies.)

Consider a couple of points:

  • If you already own a two-channel system and are trying to decide whether to get a new CD player or make the move to DVD, you've got additional purchases to make if you choose DVD. You'll need to buy a new multichannel receiver because your old two-channel receiver won't give you surround sound. (Surround sound is typically split into six channels: two front channels, two rear channels, one center channel, and an additional channel for bass.) You'll need to buy at least three new speakers because you'll need two rear surrounds and a center-channel speaker -- this is assuming that you have a subwoofer for the bass channel and your two main speakers will be employed as your two fronts in a surround-sound setup. (Some makers of multichannel receivers claim that you can get "virtual" surround sound with two speakers. What you actually get is a digital gimmick that processes the soundtrack in order to try to fool your brain into believing it's hearing sounds from somewhere other than your two speakers. It's doubtful that you, or anyone you know, will be completely fooled.)

  • A CD player is dedicated to music. What's that mean? It means that all of the electronics inside it are designed to play back music, while the gadgetry inside a DVD player is designed to reproduce video, convert Dolby Digital and DTS audio information into surround sound, enable you to zoom in on images, select multiple angles for viewing, choose different aspect ratios, and many other things. That means the dollars going into the manufacturing of a $500 CD player are devoted entirely to music reproduction, while the money flowing into a $500 DVD player is devoted to a host of other functions.

Playing the market

Even as you're reading this, technology is evolving and changes are coming to the world of CD and DVD players. CD manufacturers have all but given up on the budget and middle classes of consumers, focusing instead on the high end of the market. They've done this for good capitalistic reasons: People who are spending under $1000 on a player have overwhelmingly opted to go with DVD players over CD players, despite the arguments made by those noble proponents of CD-only players mentioned above.

It isn't so much that movies have won out over music, though some certainly make that argument, but that versatility has won out over a singular focus. A DVD player is simply much more flexible than a CD player focused on -- and limited to -- music.

Yes, that $500 CD player mentioned above might well contain a better audio DAC (digital-to-analog converter -- it converts a digital bitstream to an analog signal) than a similarly priced DVD player. It's also likely to be a sturdier component (better build quality or "fit and finish," as they say about cars), and the money spent on its electronic guts is entirely devoted to reproduction of music, but -- and this is a really big, fat but -- it won't play a movie. For lots of folks, the choice between DVD and CD is made on that basis alone.

Yet there are manufacturers and consumers holding out against the tide. Take, for example, NAD. It builds some excellent CD players at reasonable prices (see the June 2002 review of the $299 NAD C521i). Another example of a manufacturer making quality CD players under $1000 is Rotel. Both companies refuse to abandon cost-conscious consumers who demand detailed music reproduction. Other companies, like Denon and Harman/Kardon, are also trying to stem the tide with good, affordable products for music lovers.

Final points to ponder

If you're determined to keep your focus -- and your system's focus -- on music, you should avoid the megabox chainstores. The CD players they offer tend to be fixated on disc capacity rather than build quality and good sound. These stores incline towards selling players that can hold 50, 100, 500, or more discs (racing toward the day when someone can announce that the ultimate number has finally been realized: Their player can hold an infinite number of discs, plus one).

The secret to finding a good CD player is to avoid those megabox stores and head to an A/V specialist -- a dealer who stocks something other than the big-name products. Sure, they're also going to be focused on the high-end market, but they might well have some fine products in your price range. Plus, these dealers are much more likely be informed and helpful than the teenaged clerks at Megabox, Inc. peddling big-capacity players made of flimsy metal and plastic, rendering equally flimsy sound.

Flimsy sound isn't limited to CD players sold at the megabox stores. A $69 DVD player, no matter what extravagant claims its maker throws around, isn't going to give you realistic sound when listening to music or when watching a movie. However, many affordable DVD players (starting around $250) now offer high-quality audio DACs often exceeding the capabilities of those packaged in comparably priced CD players. Be sure to look for DVD players offering a 96kHz/24-bit, or better, audio DAC. Think of those numbers this way: Just as with computers, the faster the processor, the better your hardware and software will function. In a DVD player, a DAC that samples faster (96kHz over the standard CD-format 44.1kHz) can be assumed to give a more accurate reading of a disc.

After you've crunched all the numbers and read all of the product reviews, the choice between DVD and CD will always come down to what's most important to you. Is it Hendrix or Hitchcock? Or do you love both? When you've answered those questions, you've taken the first important step on the way to making your system suit your needs.


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