dschick@silver.ucs.indiana.edu (03/18/90)
In article <1554@redsox.bsw.com> campbell@redsox.bsw.com (Larry Campbell) writes: >In article <sa0KhqO00Uh7M2R25C@andrew.cmu.edu> bas+@andrew.cmu.edu (Bruce Sherwood) writes: >-The analogy with audio is that a CD with frequency response out to 10 >-MHz would not sound better than one with frequency response out to 20 >-KHz, because the human ear can't hear the higher frequencies. > >Speak for yourself. Perhaps the *average* human ear can't hear higher >than 20 KHz, but some can. I don't know what frequency they are, but >I can hear those "ultrasonic" sonar burglar alarms -- and they are loud >enough to be painful if I'm standing directly under the transducer. >But I know most people can't hear them. > >CDs would have been nice if they had a decent high frequency rolloff; but if >I A/B an LP and a CD it is clear that the CD has cut off the higher >frequencies. So I get a choice -- ticks, pops, and rumble, or missing high >frequencies. Feh. > >Anyone know if DAT will have a better high end than CDs (presumably this >depends almost entirely on its sampling rate)? Indeed, the frequency response depends entirely on the sampling rate. The fidelity, however, of the high frequencies depends on the A-D sampling rate (oversampling), the anti-aliasing filtration, the D-A sampling rate (oversampling again), and the output filtration, among a possibly endless list of other factors. The DAT recorder will sample at a maximum of 48Khz, so it should have slightly better high frequency response than the CD format. (This still won't get us anywhere near the range you are looking for however.) I personally don't have the problem with the lack of ultrasonic frequencies on the CD, but empathize with you nonetheless. Many folks in the music business claim that we perceive (not necessarily hear) these frequencies, and that their absence has a definate impact on the aural experience of the listener. Anyway, if you don't hate the concept of digital audio altogether, and are just fed up with the frequency response limitations of the current generation of gear, you might take a look at Ken Pohlman's "Principles of Digital Audio." It is a fascinating in-depth look at this wonderous new technology. If the people who claim that LP's still sound better - and I don't put you in that group Larry, as you seem to be unhappy with CD's AND LP's - would read this book, they would realize that in the long run, digital audio will satisfy even the most discriminating ears - their own! Presently, it is possible that an LP played on a Linn-Sondek with a whatever sort of tonearm and cartridge can sound better than a CD. But keep in mind that the LP is at the peak of it's evolution. Digital audio is still an infant, and it has almost caught up already! The problems associated with digital audio are not with the digital portion itself, but rather the A-D and D-A conversions. However, we are learning new and better conversion techniques everyday... As this portion of the technology evolves, we will be able to hear the true beauty of digital audio. -- Dan Schick
amichiel@rodan.acs.syr.edu (Allen J Michielsen) (03/19/90)
>In article <1554@redsox.bsw.com> campbell@redsox.bsw.com (Larry Campbell) writ >>In article <sa0KhqO00Uh7M2R25C@andrew.cmu.edu> bas+@andrew.cmu.edu (Bruce... >>-The analogy with audio is that a CD with frequency response out to 10 >>-MHz would not sound better than one with frequency response out to 20 >>-KHz, because the human ear can't hear the higher frequencies. >> >>Speak for yourself. Perhaps the *average* human ear can't hear higher >>than 20 KHz, but some can. I don't know what frequency they are, but >>CDs would have been nice if they had a decent high frequency rolloff; but if >>I A/B an LP and a CD it is clear that the CD has cut off the higher >>frequencies. >> >>Anyone know if DAT will have a better high end than CDs (presumably this >>depends almost entirely on its sampling rate)? 1. If you were to do a FFT or detailed signal analysis of LP's VS CD's you would discover that LP's may/can/do sound 'brighter' in some circumstances. a. The 'label' re-eq'ed the lp pseudo master to create a cd master. (This is the worst, & especially a problem with older stuff that the un-mixed masters are a memory, especially from smaller labels.) b. The extra LP high frequency 'response' is noise. It is nearly random and is/was (usually) NOT intended as a part of the audio program. (some high end cd players allow you to add desired pseudo noise to recreate this effect, they add a funny name but all they do is create frequency modulated noise using the actual signal as a base freq multip. 2. Human freq response is typically about 22Khz for 30Db roll off for a 20 year old male. This average changes to about 20Khz & 40Db by age 40. I can still personally hear out to 24Khz at 20Db, but also can hear it dropping over the last several years. I quite sure that human recorded max was 28Khz & 15 Db. Usually what we hear loudly from ultra sonic devices are harmonics, USUALLY. 3. If you think CD's are bad, DAT has a 45DB NOTCH cut in it at 15KHZ, that is about 1K wide above 3DB. I find this offensive cut worse than anything cd's could do. Besides, as in 1a 1b, they will sound the same because the lp noise isn;t there, & the bad eq's stuff should be all gone by the time it really hits these shores, but don't count on either. 4. If the cd's sound so bad for top freq, you could also be hearing a junk cd player. 5. If played a analog or digital, digitizing ratethat of cd or above, & given pictures of 3 waveforms, which you are listening to: The waveform type is listened to & 'taught' at a low freq, 10K or below. Then again at 18 or 20 & amplified to correct for tested subject rolloff, the resulting type selection rolls off from a average around 95% to 5%. Basically random chance. Therefore, audibly; the method by which CD's recreate higher frequency waveforms, does not make any measurable difference. I agree, the sampling rate should have been higher & given today technology would/could be. But, consider the following, if the same were said of LP technology, we would just be switching from 78's to laser read 8" analog 100 minute disks. Can you imagine your or any real stereo today, which 78's are just ending as the 'standard' media ? A standard media (any) has to make tradeoffs for the current affordable technology when the standard 'goes public'. It also has to make tradeoffs that can be sold to the market, packaged,..... Further, I believe that amyone that thinks lp's as a 'standard' will outlast CD's is in a dream world. DAT isn't the thing that will do it, and TOO much money has been gambled on it for something else to come along in time to kill of cd's soon, (IF even that is possible now, but.....). DAT's are one sided, so rewinding will return as a major Pain in the A. Then we consider tape damage & wear. Up north & down south temperature is a major source of tape death in the car. I would never consider putting a 12-15 $ abrasive original in such a environment. Then we consider getting dubbing decks for DAT's & the installed cassette car base. I believe that recording CD's will stamp out any chance that DAT may have, even for the audiofile. For most of us, DBX, dolby C, & metal tape would be sufficient. Too bad the early DBX system flaw(s) weren't fixed & accepted by the public at large. al
ma299ai@sdcc6.ucsd.edu (Jan Bielawski) (03/19/90)
In article <2486@rodan.acs.syr.edu> amichiel@rodan.acs.syr.edu (Allen J Michielsen) writes: > >3. If you think CD's are bad, DAT has a 45DB NOTCH cut in it at 15KHZ, that is > about 1K wide above 3DB. I find this offensive cut worse than anything > cd's could do. What on earth... are... you... talking about????? Jan Bielawski Internet: jbielawski@ucsd.edu Bitnet: jbielawski@ucsd.bitnet Dept. of Math UUCP: jbielawski@ucsd.uucp UCSD ( {ucsd,sdcsvax}!{igrad1,sdcc6}!ma299ai )