Letters to the Editor
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Funny that this comes up after Earth Day.
The "hi-fi" gear these guys praise was horribly wasteful on energy. The purists who still run tube amps can probably heat their living rooms with them, and vacuum tubes burn out, making a mess. Without getting into a discussion of what a Class A amplifier is, the supposed "best" amplifiers even waste twice as much power.
Even with transistor amps - hated by the purest of audio purists - there were heavy power transformers that wasted energy. Some even used transformers in the final output stage of the speakers. There was a common name for a lot of these amps: "boat anchors."
I once subscribed to a magazine of audio purists - the kind of people who built their own amps and gear, who modified old broadcast turntables to spray deionized water and photo cleaning solution with gentle scrubbers to clean old vinyl LP's. One of the projects they most prized - for which they also sold construction kits, was an amplifier bragging, "100 watts, 100 dollars, 100 pounds." You would have to reinforce your apartment floor to run two of these - that's right, that is a mono amp and you'd need two for stereo.
Rather than whine about the energy-wasting but "mellow-sounding" amps of the 1950's, these people would do better to concentrate on changing the sound of current, energy-efficient technology. For instance, if you listen to music on your computer with the popular Winamp player, you can get plug-in expanders to counteract the compression of recorded music. It makes even recorded audio books sound more lively and comfortable. (For you techies, get the VST plugin for Winamp, then look for free VST audio compressors/expanders on the Internet.)
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Objective/Subjective
While the measurable differences between different sounds (and formats) is objective, our own reception and impression of those sounds and formats is always, I think, very subjective. I am someone who mildly laments the loss of the warmth and body of vinyl. However, I notice that I have an emotional response, fueled partially by nostalgia no doubt, just at the click and hiss of the needle falling onto the record, before I even have a chance to hear the difference in the music. I think that our ears and our response to music and sound develops through our lives but that we are also strongly imprinted by the music and sounds that affected us in our youth. Anyway, I think the quality of sound has more to do with your amplification and speakers than with format, or with the care taken during the recording process rather than the actual device it's recorded onto. The best stereo systems I ever heard (worth many thousands) elevated the sound of vinyl, CD's AND cassette tapes all well above the quality of my personal system, put together for between 800-1000 dollars.
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This has been
a fantastic set of letters.
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I'm Mythed!
Full Disclosure: I'm a professional mastering engineer and teacher of audio, constantly facing this very question.
In recent years I've taught digital designers as well as musicians and engineers, and this myth frequently comes up. A constant chore I'm forced to repeat is teaching people how to hear the degradation inherent in mp3. This is a joyless task for me because it inevitably ruins the enjoyment of ripped/compressed music libraries, and forces all but the most tin-eared listeners to re-rip their tracks at higher bitrates! That's because once you hear the signature of mp3, you can no longer "not hear" it. So I urge caution for the drive-space challenged. But regardless of your situation, don't doubt that there is a difference between what's on your CDs and what's in your 128K mp3s and AACs, and the difference is not tiny or inaudible.
There are a couple very obvious artifacts that anyone can hear with very little training in Apple's AAC/iTunes codec, so that's a good place to start. If you have speakers capable of reproducing the highest octave in digital media (10k-20kHz), all you need is a way to A/B between the files (if you use iTunes, you can rip a WAV or AIF from a CD and compare it with the AAC directly from the playlist). Toggle between the source CD and AAC files, paying close attention to the high end. You will hear a pretty large difference: The AAC will sound more harsh and bright on the high end, but be missing the airiness and space of the CD. This is because the encoder strips off everything above 15K (half of the top octave is gone!), and the perceptual codec OVER-emphasizes the remaining high frequencies to compensate. These changes will present as a harsher overall edge to the top, and sometimes the timbre/pitch of individual sounds in the high end is very different when compared directly. So much for perfection, the goal of the codec is "sufficiency" and euphonics (good, pleasantly distorted sound).
The other major difference we can hear is spaciousness and depth. Specifically the stereo image is much less defined after lossy encoding, and the codecs move low frequency stereo positions to mono (much like we do when mastering to vinyl, actually!). Again, the extremes are over-emphasized pushing some sounds far to the left and right, while subtle panning and positions are lost entirely. Sounds panned only slightly to either side can become mono. So, as we switch between source and coded, the "performance space" will change in size and shape. With electronica, or artificially defined spaces this might sound better to our ears (euphonics again), but it's NOT what the composer/producer heard or intended or delivered in the mix. Just a close facsimile.
The joy-killing technique I use to teach the sound of these codecs is a little tweaky. Most digital audio workstations are capable of encoding a stereo signal in a format known as "Mid-Side" or "M-S", either directly with a plug-in or indirectly with bussing. This technique generates a different kind of stereo file; instead of Left and Right channels, we have Middle and Side channels (one of each). When teaching the signature to clients or students I encode a file very aggressively (64K bitrate) and another at a higher, more standard 128K, along with the source PCM. When you listen to the S channel of a 64K file, you can hear what's colloquially called "space monkeys." Most people instantly recognize it as the jangly/swishy/ringing sound that accompanies Real Audio streams (which is the same thing). After hearing it alone, without the music to mask the artifacts, you become sensitized to it. After a few minutes, we switch to the 128K file and repeat the exercise, listening to the S/Side channel. Most people instantly hear it in the cymbals and high frequency of the higher quality file, because their ear has been "trained" by the lower res file. Listen and learn it long enough, and you'll hear it all the time.
Interestingly, I think this is the main reason why Apple chooses to chop off half an octave on top. Those sounds challenge the codec, and are the first to become "space monkeys" in a mix. By removing those frequencies entirely (which MP3 at 128K doesn't always do) you remove the artifacts as well, making the files more like the source, at least up to that frequency.
At any rate, half an octave isn't a small thing, and how and what happens in that octave makes a big difference in sound quality. These aren't microscopic differences only audiophiles hear, but real parts of the music and space the artist intends you to hear, but the codec denies you. Every dimension of sound compromised in the encode/decode cycle, there's no free lunch. What perpetuates this myth is listening venue. If one always listens through small speakers or headphones, and never hears the source next to the smaller version, the differences will seem smaller than they actually are. Until you learn the sound of the artifacts you won't hear them. The problem is you eventually will learn that sound, but if your entire music collection is crippled to 128K, you'll be forced to settle for less, and make up excuses or pretend you can't hear it.
I'm reminded of the early days of stereo. Many people denied it was an improvement over mono, and that denial persisted for decades. Early on artists struggled to use the new presentation mode in all kinds of creative ways. As with stereo, the sound has changed, but that's just half the story. The real story is the new venues for listening, and new markets/places for music, made possible by these tiny, decent sounding files.
-d-