Quote:
Originally Posted by
Mac-sochist 
The problem isn't dynamic range
per se, it's digitization error when only a small part of that range is being used.
That problem, quantization error, isn't really a problem, because it was understood quite early in the CD era. Convolution (dithering) of the low bit signal (such as you hear in the last embers of a final piano tone) has eliminated that problem.
Also, while that is a theoretical problem, it isn't much of a practical one. The low level signals that you are talking about are already so low in volume, that the residual distortion caused by this is so much further down in level so as to be unhearable, unless you press to the speaker. We're talking about components that are 100 db down! Lower than the noise level of most components the signal is passing through.
Quote:
Artifacts and distortion are not all created equal. The problems to which vinyl was heir (noise, limited dynamic range, etc.) are annoyances that occur in the natural environment. Our auditory cortex has evolved to filter them out and listen past them. That's not true of some of the distortions that have been introduced by technology and that it was blithely assumed "no one could hear."
I've been to many a live concert over the years, and I've yet to hear any of the distortions that vinyl is subject to, there.
We certainly haven't evolved to hear record noise, harmonic and IM distortion, etc. It's very obvious when playing records, and when listening to certain tube equipment.
I've yet to see any actual proof, done through properly set-up listening tests, that show that we can hear the very low level distortions of a good CD, but not that of a good Lp. I'd love to see one.
Most of this is hearsay, from people who have an interest in believing so.
Quote:
The first solid-state amplifiers did very well on harmonic distortion, but they used a push-pull arrangement, which while the characteristic curve looked nice and linear in the middle, thus introducing no harmonics, did have a discontinuity there which introduced "anharmonic distortion," something nobody was checking for, and something that never happens in the real world, giving a sound quality that was absolutely intolerable. But measured distortion was low, so who cared?
Uh, what are you talking about? The earlier solid state amps used quasi-complementary circuits. Before that, they weren't even that sophisticated.
But the problems of early (through the early '70's, to about 1972-3) solid state amps were due to a type of distortion called "TIM", or transient Intermodulation Distortion. This occurred for two reasons. One was that solid state amps had a much more extended high frequency range when compared to tube amps of that time. Two was that early transistors had a low frequency range. That sounds incompatible, and it IS. Once they recognized that TIM was the cause, they rapidly eliminated it. I'm not going to get into the theory involved, but will say that the problem wasn't recognized early on because tubes, due to their nature, weren't reproducing it because of the high frequency roll-off (and other reasons). Therefore, it didn't occur to engineers that TIM could exist in an audio amp.
"Push Pull" was invented in the late '40's by Williamson. It was first used for tube amps, because solid state wasn't around then. In honor, that amp design is called the "Williamson Amp".
It is the first modern amp design. Before that, all amps were of the type called "SLT", or "Single Ended Tube". All amplification was done with a positive going signal. But that kind of amp has many problems, and died out quickly after the "push pull' came out. More recently, it has made a comeback amongst a certain group of audiophiles who don't mind its high distortion, poor frequency response, and very low power. They claim that it has other qualities that more modern tube and SST amps lack.
Quote:
The first CD players use analog filters to remove everything above 20 kHz. It was by definition "noise" since it couldn't be recorded on the disc at that sampling rate. Unfortunately, they used a Chebyshev filter, which gives a nice flat frequency response, but introduces phase distortion close to the upper limit: another thing "nobody could hear." Well, they could!
"Brick Wall filters have their problems. The biggest problem was that of "ringing". At the filter point, the frequency response is unstable, and "rings". That is, it varies about the cutoff point. Some people claim to hear it, while others don't. The actual frequency is about 21.5 KHz, which is above the hearing limits of most younger adults (about 23 and up, if they are lucky, if not, 16 and up)).
Phase distortion is interesting. When designing speakers and anything using filters, it was something I had to deal with. Unfortunately, phase shifting is something that can't be eliminated in the analog world. That's because it's the phase shift itself that's doing the work. No phase shift, no filtering!
What is well understood about phase shifts and human hearing, is that we can't detect slow phase shifts. That is, phase shifting over a long frequency range. If phase is +720 degrees at 50 Hz, and -720 degrees at 15 KHz, we won't hear it. But, if phase shifts from, say, +180 degrees to -180 degrees between 750 Hz and 1,250 Hz, we will hear it.
It's debatable if phase shifts at. or above. 21 KHz is audible though. If we can't hear the frequency involved, then it's not likely we will hear the phase shift associated with it, which is moving up in frequency, not down.
Quote:
Stereo was designed to create an illusion of localization by simply varying the loudness of the signal to move the apparent location from coincidence with the left speaker to coincidence with the right, and in between. Unfortunately, if a rapid-onset sound like a drumbeat reaches the ears in the real world, you will hear two arrival times, one for each ear. In stereo reproduction you get four, two for each speaker, which creates confusion in the auditory cortex and prevents stereo from working as advertised. Phase was another thing the human ear couldn't detect, and since it was tested with continuous sine waves, that was true: until you listen to real music! (Of course five-channel gives you ten arrival times to sort out!) The only solution is headphones (but they don't allow a real perception of sound coming from straight ahead; it will seem to rise up kind of above your head) or Carver Sonic Holography™, which died with the second of the three corporations Bob Carver had stolen out from under him by insensate bean-counters.
While I understand what you are saying, it's wrong. It's well understood that stereo works. That's not the problem. It only takes a 9 db difference in level to mask out the other channel completely for a similar sound in stereo reproduction. There is also the time difference, which is most certainly on both the Lp and the CD.
How do you think the microphones pick this up? They are in different places, and "hear" the music at different times, with difference loudness, and phase. This is reproduced in the recording.
Sometimes binaural microphones are used, where a simulated head is used, with the omnidirectional mics where the ears are. They get the same spacial relationships we get. The "cross mic" set-up is also sometimes used. That's where two (usually) cardiod mics are crossed over each other so that the left mic points towards to right and vica versa.
I happen to know Bob Carver from way back. His ideas were well ahead of their time back then, but are still being used today.
He invented quite a few things, but Sonic Holography was an interesting one. It's actually the basis of most multichannel systems today.
The biggest problem Bob had with it, was that he was trying to do something in the analog domain that was better done in the digital domain. The problem was that there WAS no digital domain when he was working with this! It was amazing that it worked at all, much less as well as it did.
Quote:
The list of things "the human ear can't detect" is added to every time a new technology comes along, and usually disproven. Only this time, it seems like crappy music downloads are finally going to make it stick!
Unfortunately, we can't detect many things some think we can detect. While our eyes are given one million neurons to work with, our ears must make do with thirty thousand. We can;t discriminate as much as we like to think we can. Again, as I said earlier, hearsay is worthless. Without proper listening tests, we can think anything we like. And thats fine, just as long as we don't push it upon others.
I'm always happy for someone when they tell me that the equipment they now have is enabling them to enjoy their music more than ever before, even if that equipment make me want to cringe.
