Ameesh --
can we get somee EE (acoustic) people to respond to this dummy?
brxndxn --
<< people who think CD quality is pretty poor should try listening to a crackly vinyl... or an audiocassette.. or pulling their head out of their perfecltly acoustic ass >>
The medical term for the condition is
Anal-Cranial Inversion, and your statements show that
both of you suffer mightily from it. I could tolerate your ignorance, which is merely a lack of information, but you're both stupid enough to be quite rude to others while demonstrating the depth of that ignorance. :Q
Welcome to Reality 101. I am an electronic design engineer, and I design audio electronics, primarily analog products for the recording studio and broadcast markets. You have heard of some of my clients, I promise.
It starts with the fact that CD's suck compared to old analog recordings, but we'll get to that at the end of this piece. As you know, CD recordings contain data -- sixteen bits @ 44 KHz x 2 channels, plus other identifying info, such as the title and location of tunes on the disk and control and formatting information. A complete CD holds about 650 MB. It's not exactly accurate, but if there are ten tunes on the disk, then about 65 MB would be enough for one tune. There simply is not enough bandwidth on a 56K line to transfer an entire CD and play it in any kind of useful time.
Enter data compression. Unlike PKZIP, which is a lossless compression scheme that allows you to retrieve all of the original information in the file, MP-3, Dolby AC-3 and other, similar formats use lossy compression. In these schemes, a computer uses principles of psychoacoustic masking eliminates parts of the sound it "thinks" you can't hear under the louder parts of the sound.
Here's a clue. I belong to a couple of professional audio groups. At one meeting, we ran a CD through a Dolby encoder and digital delay that gave 100% accurate data with enough delay to match the output from the encoder in time. We then subtracted one output from the other. What remained was just the parts that the computer removed. Every person in that room who was experienced in recording was shocked. What we heard was a bunch of subtle subtextures, such as room echos and other audible cues that no experienced recordist would want left out of their carefully crafted mix. In other words, such schemes will never give you an exact copy of your CD.
As I said at the start, CD's suck, too, compared to original sounds. The sampling rate is way too low, and there just aren't enough bits. The inherant distortion in CD's is non harmonic. That means, unlike harmonic distortion (THD), the distortion products are out of tune with the music, which, in turn, means that human beings are far more sensitive to this kind of distortion. If that wasn't enough, unlike almost every musical sound generator, amplifier and speaker, the distortion gets worse as the music gets softer. Therefore, when it's full bore blowing your ears into distortion, it's as clean as it's going to get. In a moderately soft passage, where your ears are more sensitive to distortion, CD's are glad to give you lots more distortion.
44 KHz is an inadequate sample rate. This sampling rate was chosen based on Nyquist's theorem, which states that, to recover a given frequency, you must sample the information slightly more than twice the highest frequency. The problem is that Nyquist wasn't a musician. As you get closer to the high end of the audio spectrum, this theorem is only valid for a single, steady state tone. If you change the conditions to allow for a second tone, or to modulate the amplitude (volume) of the sine wave while it is being sampled, you have created a condition where there are literally an infinite number of possible outputs for a given sample. As a designer if analog gear, when people ask me how many bits I want, I always answer,
All of them! 
No matter how many they have, I have more.
I used to be a professional musician, too. Music (and any art form, for that matter) transcends the medium. It isn't just counting to four and getting the notes in the right place. The subtle undertextures of a musical performance are part of the "magic" that moves your soul. When I turn off the scopes and meters and just kick back to play or listen, CD's don't cut it. I have CDR's in my machines, but I don't own a CD player.
If you want to hear the difference, get ahold of an old LP in good condition of something that was recorded analog, and a CD re-issue of the same thing. Cue them up so they are in sync, and switch between them. LP's win every time. Good examples would be Eagles, James Taylor, older Steely Dan and anything else with good air space in the recording.
kami --
<< hmm, you haven't heard DVD-Audio have you? >>
Soccerman --
<< he problem with analogue audio (whether it be tapes, or records) is that they don't stay at the quality that they come in. >>
When CD's first came out, some friends and I proposed a perfectly good way to do analog on a laser disk. It's called
FM, just like your radio. FM was used for the audio in the original 12" video laser disks, as well as Beta and VHS Hi-Fi, and if you don't have to deal with the problems of reaching remote locations with a broadcast, or giving up storage space to video, you can record gorgeous audio tracks that are as durable as any other laser recording. I've seen internal Sony documents that support the same idea.
There is hope on the horizon. The highest standard for the new
audio only DVD (not necessarily the same thing as DVD-A) is two channels of 24 bit data @ 192 KHz with only lossless compression. At that sampling rate, it will once again matter if the analog electronics I design can do a good job of reproducing the signal.
Don't worry. It's a multi-format standard that is compatible back to current CD's, so you'll still be able to play them. Of course, once you hear the new stuff on a good system, you may not want to, anymore. We may finally be about to come out of the
Audio Dark Ages.
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