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| [#116] CD quality no worse than High Resolution Playback http://www.drewdaniels.com/audible.pdf From Gary Galo (Audio xpress magazine) The inability of many to perceive the differences between the CD and high resolution formats was documented in an article recently published in the AES Journal, “Audibility of a CD-Standard A/D/A Loop Inserted into a High-Resolution Audio Playback.”1 Authors E. Brad Meyer and David R. Moran, both members of the Boston Audio Society (as well as AES), conducted a series of double- blind listening tests over the course of a year using an A/B/X box. These tests compared the direct output of an SACD player to an A/D/A conversion at the 16-bit/44.1kHz CD standard. In other words, the analog output of the SACD player was fed through the CD-standard conversion, and an A/B/X box was used to switch between the direct output from the SACD player and the output from the CD-standard converters. Out of 554 trials, there were 276 correct answers— no better than “coin flip” results. To those of us who have recorded in both high-res and CD-standard digital, the conclusions seem ridiculous. Several recording engineers and audio professionals I spoke with found the conclusions baffling—either the participants can’t hear, or there’s something seriously wrong with the test. I know a number of people who work in the audio field and seem to fit the “can’t hear” category. One recently told me that he did not believe that the Sony PCM-F1 digital recorder had any audible shortcomings. In other words, digital audio today doesn’t sound any better than it did in 1981. In their conclusion, Meyer and Moran admit that “virtually all” of the SACDs and DVD-Audio recordings they heard sounded better than most CDs. But, they don’t believe this can be attributed to the inherent superiority of high-res digital formats. From discussions they’ve had with engineers who work on commercial releases in high-res formats, they conclude that the extra care taken in the production of SACD and DVD-Audio releases accounts for their superior sound (I’d be willing to bet that much of this “extra care” involves things that A/B/X testing would fail to substantiate). But, this doesn’t account for the proliferation of dual-layer SACDs in which the CD layer is identical in production to the SACD layer, except for a conversion from DSD to 16-bit/44.1kHz PCM. Such SACD discs include the RCA Victor Living Stereo series and the Telarc SACD catalog (the Mercury SACDs are an exception, because the CD layers areWilma Cozart Fine’s older CD transfers, and are thus different from the newly transferred SACD layers). On my own equipment, the differences between the SACD and CD layers are readily audible. Yet the conclusion of Meyer and Moran is that “Our test results indicate that all of these recordings could be released on conventional CDs with no audible difference.” In their view, “Further claims that careful 16/44.1 encoding audibly degrades high resolution signals must be supported by properly controlled double-blind tests.” Apparently they believe that recording engineers such as Tom Jung are simply deluding themselves. Perhaps we also need a series of A/B/X tests to verify whether there are any visible differences between HDTV and NTSC. DIGITAL DOMAIN One manufacturer who was demonstratingDSD recordings was ATC Loudspeakers (www.lasvegasproaudio.com). Their SCM150ASL 3-way active loudspeaker was used in a 5-channel surround system with a full-range center channel. Digital hardware included DSD playback equipment from EMM Labs, a company run by renowned digital hardware designer Ed Meitner (www.emmlabs.com). The jazz recordings featured in this demonstration were made on a Sonoma DSD Recording and Editing Workstation, using Meitner-designed DSD converters. Unlike some editing systems used in the production of SACDs, Sonoma’s “DSD Pure” system keeps the audio in the DSD domain at all times (Photo 1, www. superaudiocenter.com). Although the recordings were impressive enough, I don’t think the playback system revealed their full potential. In Sonoma’s product literature, Tom Jung offers the following endorsement: “The Sonoma system, when optically interfaced with Ed Meitner’s DSD converters, is the most musically accurate recording and editing system available today at any price.” Sonoma boasts endorsements from several other renowned engineers and producers, including Telarc engineer Michael Bishop, who states: “I’ve recorded to analog tape for well over 30 years and to digital nearly as long. The Sonoma 32-track DSD workstation gives me the quality of analog—without the drawbacks—plus the convenience and speed of a DAW.” Two manufacturers were promoting Digital eXtreme Definition, or DXD, converters. DXD is a 24-bit PCM system operating at a sampling frequency of 352.8kHz, which claims to offer the resolution of DSD with the ease of editing of PCM systems. One of the disadvantages of native DSD editing is the limited signal processing capabilities compared to PCM editing systems. With the DXD system, you can make a recording in DSD format, convert it to DXD for editing on a DXD workstation, and then convert it back to DSD to make the finished SACD master. Or, you can record the original in DXD, edit it, and convert it to DSD for the finished SACD product. Digital Audio Denmark (DAD, www. digitalaudio.dk) exhibited its AX24 multi-channel converter, noting that “24- bit DXD at 352.8kHz is the perfect work format when producing SACDs (Photo 2). It offers the editing and processing advantages known from PCM and converts smoothly to DSD.” Digital Audio Denmark further notes that the DXD format is supported by Merging Technology’s Pyramix 5.0 workstation. Merging Technology’s exhibit featured the Pyramix workstation (Photo 3), now in version 5.1, along with its own Sphynx 2 DXD multi-channel converters (www.merging.com). TheSphynx 2 was jointly developed with Digital Audio Denmark, and appears to be virtually identical to the DAD AX24. On their website, Merging Technologies makes the following case for the Pyramix system in DSD/SACD production: “For those who want to work in the DSD domain at 2.82MHz sampling rates for SACD production, Pyramix has a unique answer. . . It is the first system in the world to offer multi-track record/ editing and mixing as well as mastering while maintaining all the real-time audio processing (effects) such as EQ, Dynamics, Reverb and Surround Sound in a DSD compatible quality level up to the final SACD master. Quite simply, to have only a mastering capability for DSD is not enough. Unless you can record, edit and process the signals in a true multi-track configuration, mastering makes little sense. “Pyramix is the first system with enough processing power and resolution to handle in real time a complete digital mixing console capable of operating in 32 bit floating point at 352.8kHz, which is the minimum requirement to preserve all the intrinsic original quality of 1 bit 2.8MHz DSD signals. With real-time EQ, Dynamics, Reverb, etc., and with full SACD scarlet book specification for mastering, we can truly state that ‘Pyramix is the only commercially available system on the market that is capable of a complete multi-track source to master project for Super Audio CD production.’ " Regarding the DXD format, they note: “A new format, DXD (Digital eXtreme Definition for high quality and low noise recording and editing for SACD), hasrecently been acknowledged by Philips and Sony. DXD was initially developed for Merging’s Pyramix DSD workstation and recognized as one of the best formats for DSD source recording.” The Sphynx 2/AX24 converter was used on an excellent SACD of Mozart Violin Concerti Nos. 3, 4, and 5, performed by Marianne Thorsen with the Trondheimsolistene led by principal cellist Oyvind Gimse, on the Norwegian 2L label (www.2l.no). Digital Audio Denmark handed out a sample copy of this recording containing two discs with identical programs, an SACD and a conventional CD, thus making it easy for the listener to compare the two formats without going into the SACD player’s setup menu. Levels between the two discs appear to have been precisely matched. To my ears, the SACD is superior to the CD—more spacious, with a silkysmooth treble region that becomes slightly grainy on the CD. The CD also sounds as though it were recorded in a slightly drier venue than the SACD. A single-disc, dual-layer version of this recording is available from a numberof Internet dealers, including ArkivMusic(www.arkivmusic.com/classical/album. jsp?album_id=146118). The SACD version makes a strong case for the transparency of the DXD conversion process, though I admittedly have no way of hearing the original, prior to DSD conversion. The audio community is fortunate that there are still a few manufacturers committed to advancing the state-of-the-art in audio recording. Those of us who care about high-quality sound can only hope that room will remain in the marketplace for such companies. They face an uphill battle against those who claim that it makes no difference, and those who simply don’t care. Keith O. Johnson, the recording engineer responsible for the material on the Reference Recordings label, gave a master class titled “The Art and Science of Making and Playing Great Recordings— The High Resolution Experience.” Johnson is also the co-designer of the HDCD system, which Reference Recordings is still promoting. They have not issued any SACD or DVD-Audio discs, but their website notes: “We record two-channel masters at 176.4kHz, 24- bits, and discrete five-channel mastersat 88.2kHz, 24-bits for future release in high-resolution surround sound” (www. referencerecordings.com). The large room provided for this 90- minute presentation contained a multichannel surround system with Parasound Halo-series electronics driving PMC BB5 loudspeakers that appeared to be quite capable of providing highdefinition sound in a large venue (PMC is a UK-based company specializing in high-resolution professional loudspeakers; www.pmc-speakers.com). Unfortunately, Johnson’s presentation was not well timed. He spent too much time at the beginning discussing the hearing mechanism, and left little time at the end for playback of recordings. This was unfortunate because his recording of the Rachmaninoff Symphonic Dances—what little of it we heard—was very impressive. His presentation would have been more meaningful if he had interspersed recorded examples throughout his talK by gary galo (Audio Express) |
batmanamesIA 正式會員74.xxx.xxx.50 |
2013-07-12 03:04 | |
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| [#115] CD quality no worse than High Resolution Playback http://www.hometheaterhifi.com/musician-and-vocalist-artist-interviews/musician-and-vocalist-artist-interviews/mark-levinson-for-the-love-of-music-part-2.html Written by Scott Wilkinson Published on 03 July 2013 . FacebookTweetGoogle +1ShareThisPinterest Earlier this year, I had the privilege of interviewing Mark Levinson, one of the most influential men in the entire high-end audio industry. We spent hours discussing a wide range of topics—so many, in fact, that they could not be squeezed into a single article. If you haven't yet read part 1, I encourage you to do so before moving on to part 2. Here, Levinson shares his thoughts on analog versus digital audio, the effect of cables on sound quality, 2-channel versus multichannel music, movie soundtracks, and the problems facing consumers shopping for audio gear. Analog vs. Digital Audio Naturally, I was interested in Levinson's take on analog versus digital audio. "For me, the first thing is the content. If the content is only available on SACD or CD or LP or download or wherever, that's what I'm going to listen to, because if I don't, I won't hear it at all. If it's a recording I want to listen to, I don't care what it's on, I want to listen to that particular piece of music. "Every recording medium has its limitations. I've always liked analog tape, but it's very expensive and messy. The recorders are big and heavy, and you have to calibrate them with mechanical and electrical adjustments. It's very time consuming and requires a lot of test equipment. Plus, the tape stock varies and can be hard to get. It goes on and on." What about digital? "There are two kinds of digital audio. There's PCM (pulse-code modulation), which is used on CDs and DVD-Audio, and DSD (direct-stream digital), which is the basis of SACD (Super Audio Compact Disc). In terms of sound quality, PCM has always been a mixed bag; there have always been people who don't like it. Dr. John Diamond went further than anyone in understanding the problems of PCM, but the world didn't want to hear what he had to say." For more on Diamond's findings, see www.drjohndiamond.com/digital. "On the other hand, DSD was very well received from the outset. The problem was fraud, which occurred when Sony wanted to popularize SACD and took PCM recordings and converted them to DSD and expected people to get excited about it. But in fact, they were giving people the same thing they already had on CD, but in a different format. "What Sony really wanted to do is stop piracy. If they had said that, it would have been fine. But instead, they tried to tell people how great DSD was, and then put out CD material as SACD. No wonder people weren't impressed! They were being sold the same thing they already had. "In some cases, the audio was recorded in DSD but converted to PCM for editing. In fact, that was common because Sony didn't make any tools like EQ or compression for DSD. So engineers recorded in DSD, converted to PCM for processing, then back to DSD for the final SACD. This wiped out the advantage of DSD; it was a travesty. "When DSD is done properly, it's very transparent. But it requires very good converters. It's full of promise, but it has been largely abandoned. A few record companies still put out SACDs, mostly because it's almost impossible to copy them, which was Sony's original intent. "In the end, Sony abandoned the medium and did not make any tools for engineers to use. So if you wanted to do any post-processing, you had to convert to PCM. By comparison, you can get a set of plug-ins with 300 different algorithms to use for mastering PCM. For DSD, there's nothing like that. "Using John Diamond's methodology, we tested PCM systems up to the full resolution of DSD. In that case, we recorded in DSD, then sent the data through a PCM processor called DSD Wide with 32-bit floating-point resolution, then converted it back to DSD. And it failed. We proved that it isn't bits or bandwidth or resolution. It's something else. There's something physiological going on. "The industry is in no great rush to do any testing for this sort of thing, because they want to make money by investing the least amount they can get away with and get the maximum return in the shortest time. The principles of return-on-investment dictate that any scrutiny be kept to a minimum; as long as they can sell it, they do it. It's putting the customer last." Despite the controversy, Levinson is focused on optimizing PCM because that is the global format of all music and audio. "To me, the most important thing is that musicians need income, and the way things are going, they're not going to get it from analog LPs or SACDs. We need to make PCM work, so we can continue to have musicians on the planet. My goal is to make PCM sound and feel more like analog or DSD, and I've made some progress in that direction. In that process, PCM becomes acceptable to me as a medium." Levinson will soon release a new audio-software product for the Mac called Master Class that is, in part, a digital version of his legendary Audio Palette. "The Audio Palette was for the privileged few; Master Class does everything the Audio Palette did and much more, yet is within reach of a wider audience." The Great Cable Debate Another contentious topic is the effect of cables on the sound of an audio system. As Levinson recounts, "Let's say you put a sine wave into a preamp, and you have a cable between the preamp and power amp. At the output of the power amp, you measure the frequency response. If you change the cable between them, the measured frequency response will change slightly, which shows you that a lot of what we hear is the result of small differences in frequency response. I'm not saying that all cables are like that, but more than anyone would guess, this is what's happening. "At Daniel Hertz, we built a box with a stereo input and stereo output. It also has a stereo loop and a switch. With the switch in one position, the signal goes straight through from input to output, and in the other position, the signal goes through the loop. The idea is to connect a cable to the loop and see if you can hear a difference in the sound due to inserting that cable." What were the results? "The effect of different cables was sometimes audible and usually measureable, but the differences were generally small. Plus, the effect of the cable depends on the situation. You're not listening to the cable alone, you're listening to the interaction of the output impedance at one end, the input impedance at the other end, and the cable in between. You're listening to the interaction of impedance, inductance, and so on." Of course, in Levinson's cable tests, all the electronics and cabling (other than the cable being tested) were the same, and the relationship between output and input impedances were optimized for high-quality audio, preventing these elements from undermining the results. In addition to a preamp, power amp, and speakers, Daniel Hertz also makes interconnect and speaker cables—or, to be more precise, one interconnect and one speaker cable. "Our cables are based on three factors. First, silver is the best known conductor of electricity; copper is number 2, and gold is number 7. Second, Litz construction offers the lowest inductance, and third, Teflon dielectric offers the lowest capacitance. So that's what we use. And we only need one cable, not 10 or 20 different models. Why? Because it's transparent, end of story. No one so far has been able to hear any difference in our interconnect cables connected to that loop/switch box. Daniel Hertz Premium 500 speaker cables include 500 strands of individually coated silver wire in a Litz configuration, yet they are no thicker than a pencil. "In my opinion, the high-end audio-cable business is mostly a farce, and in some respects it's based on deception and fraud. The definition of fraud is willfully misleading the public for financial gain, and that's exactly what I believe many of these cable companies are doing. They know it's not real, but they do it anyway. It's unethical, and I deplore it." 2-Channel vs. Multichannel Music With his deep knowledge and experience in music recording, I wanted to find out how Levinson feels about multichannel recordings as opposed to traditional stereo. "There's merit to all formats—mono, 2-channel, 5-channel. The listening experience depends on how well the format is utilized. "Most surround-music recordings are gimmicks. When we listen to music, the sound is usually coming from in front of us. In general, music in surround has not been effectively utilized, but the potential is there. If you want to have the music come from all around, that's fine, but I would use multichannel music recording differently. "Bell Labs published some papers in the 1930s, and Paul Klipsch gave me a set. These papers described the advantages of different multichannel formats beyond mono. They ended up recommending three channels—left, center, and right. But because of the technical limitations at the time, they settled on left, left+right in the middle, and right. They never really advocated 2-channel stereo. Paul Klipsch also advocated exactly that. "It makes sense. You want music in the center, so how can we get that without a speaker in the center? Stereo works on the phantom-center principle, but the ideal would be to have three channels. It just hasn't been practical until now. How do you make an LP with three channels? "In the 1950s, some Ampex recorders were equipped with 3-channel heads, and they used three microphones. They mixed it to mono or stereo, but they actually had the foresight to think that someday there might be a 3-channel reproduction system. But if you made a 3-channel recording, say with three microphones across the front, how would you play it back? What would you do with the surround channels? At this point, it's an experimental idea. I'm just not sure how it would be made compatible with the world. "In any case, the key is not the format, it's the content. What's the content, and how do you use multichannel to enhance it? In most cases, the music is in front of you, so the best you can do is put reverb in the surround channels. "The industry has become obsessed with complexity and over-produced results without enough thought given to the content itself. It's the number of channels or bandwidth or dynamic range or something else except the quality of the talent, the quality of the music. The attention is on parameters, not on soul. I know of mono recordings from the 1950s that are infinitely more enjoyable than many modern recordings, not because of the format, but because of the music. "Among the many recordings I've mastered, the one that people have fallen in love with the most is a 1950s recording of Charlie Parker playing 'Out of Nowhere.' The original recording quality was what you would call primitive; no audio store would use it in a demo. I remastered it, which produced a file that has people mesmerized. It feels like Charlie Parker is in the room with you, it sounds like a contemporary recording. "When I was demonstrating the Daniel Hertz system at CES, I met a guy who produces a jazz radio program in Chicago. He told me that the single most moving thing I played him was that track of Charlie Parker. That alone was worth the trip to CES for him. That's what I'm trying to say—the purpose of the equipment is to experience the content." Audio for Movies These days, of course, movie soundtracks are multichannel by nature. But when Cello got involved in home theater, Levinson recognized some problems with that paradigm. "We realized that, in many ways, surround sound was flawed. It was designed for movie theaters, in which you can't have a left and right channel; people far from one channel in a large theater can't hear it. Movie theaters have to be mono. "But then they added incidental sounds in the surround channels. If you shut off the surround channels, you won't miss anything. It might be more interesting to hear the incidental sounds, but they do not contain anything necessary to understanding the movie. All the dialog, music, sound effects, everything of importance is in the center channel. "When you get into a home, most people have a television. You can't put a speaker behind a television like you can in a theater with a perforated screen. So the one channel that's carrying all the dialog, music, sound effects—99 percent of the information—is the smallest speaker in the system. Those nice big speakers on the left and right of the TV don't do anything. "This is a very tough problem. It doesn't bother the big companies too much because they sell by marketing, they get everyone to buy, so they're making money. This is an example of the true illness of the industry right now, which is that the customer comes last. The first thing is profit for manufacturers and dealers—whatever makes money, they do it. "If you really want to know the truth, try listening to two really good speakers and electronics, then take that money and divide it up 5.1 ways and see what your money will buy you. If you like the 5.1, buy that. If you like the 2-channel, buy that. I'm not advocating one or the other. What I'm saying is that the way the industry is set up now, you're buying six channels of amplification and six speakers, and 99 percent of what you are hearing in a movie is coming from one speaker, the center. Listen for yourself, see what you think. A lot of people find that their money is better spent on two good channels than six mediocre channels. "Even if you have a great center channel, where are you going to put it? You can't put it in front of your TV, and you can't put it behind your TV. It has to go underneath or above it. Another alternative is to use speakers on the right and left of the screen and run them in mono. Then, it will image right in the middle of the screen. But that's not the industry standard." Levinson also notes that movie soundtracks are not accurate representations of real-life sounds. "In real life, if a helicopter lands in front of you, you know it. With many sounds that people experience when they're watching a movie—like a gunshot, door slam, or helicopter—there's no way a normal audio system could even approximate that sound. "On the other hand, if someone says, 'I'd like to see how close we can come,' we can do that. But it requires a whole lot of science and a whole lot of money. "There are really three areas you want to think about in terms of audio. One is tone and timbre. Does a voice sound like a real voice? Does a guitar sound like a real guitar? Is the sound natural? The more natural it is, the more you get into the story. The less natural it is, the more removed you are. "The second one is bass. Good bass is expensive; the deeper the bass, the more expensive the system is going to be. But it's not only low frequency response, it's also the quality of the bass. It can't be tubby or boomy; it must be clean. "The third thing is dynamic range. For example, let's say someone fires a gun six feet away. That is going to be a very loud sound. There's no way you can reproduce it on normal audio equipment. Even the most dynamic systems are challenged by something like that. "Film soundtracks are not accurate. They are designed so they won't distort when reproduced on even very inexpensive systems. For example, a television with built-in speakers the size of a quarter can't distort or people won't like it. So they have to homogenize the tracks so they won't distort when played on extremely simple systems. "This means the dynamic range has been compressed and the frequency range has been limited. They have to do that, otherwise they'd be creating a lot of customer dissatisfaction. While you might want to reproduce a gun shot or helicopter, that isn't going to happen. Not only are most audio systems incapable of reproducing these sounds accurately, they can't even be captured completely. "That being said, what's the best you can do under the circumstances? There is enough information that, if you take care in designing the audio system, you can have amazing results. But the problem is, there are different levels of quality. People generally understand that a TV's picture looks great or not; it's a pretty easy concept, because you can see it. But with audio, most people are not as connected to the technology, so it's a little more difficult to understand the importance of the audio system." Shopping Advice Levinson recognizes that consumers are at a distinct disadvantage when it comes to shopping for audio gear. "One of the biggest problems for consumers is, where do you get your information? On what do you base your buying decision? How do you form your opinions? The best way is direct experience, but that isn't always practical or even possible. So you can read reviews and such, but most people don't have time for that. "So most people go to a store and talk to a salesperson. There are some great people in retail, and if you go to the right place and talk to the right person, you can get some great help. But for every great one, there are 1000 people who are not educated, so they are not in a position to help you. "Worse, they are given directives by the management to sell one product or another. Or manufacturers give them a spiff. So they have these incentives, which means the consumer is in a difficult position. The industry is controlled by big money. These multibillion-dollar companies pay for the ads and finance the inventory. They control what happens, and the consumer must survive that. "This is one reason why there is still a place for the specialty store. In the early days of audio, these were family-run businesses, and they loved what they did. It was friendly. Sadly, most of these family stores went out of business because of the big chains. "The Internet can be very helpful, because you can read what consumers say about their experiences with a product. Amazon has used this concept to great effect. It's what the Internet was designed to do in the first place: share information. "There is also a place for knowledgeable, trustworthy, articulate reviewers, and the Internet provides an avenue to get that information to consumers. In that respect, it's a great solution to the problem we're talking about." Coda As you've no doubt discerned by now, Levinson's first priority is to reproduce music recordings as accurately and faithfully as possible with equipment that is well-engineered, robust, and easy to use. He is justifiably proud that products he designed decades ago were manufactured for many years with virtually no change, and they're still going strong, commanding high prices on the used market—if you can find anyone willing to part with them at all. What does the future hold? If the past is any indication, Mark Levinson will continue his quest to create the best-sounding, most bulletproof audio products for true music lovers everywhere. And I have no doubt that we haven't heard the last from this man of singular passion and vision. |
batmanamesIA 正式會員 74.xxx.xxx.100 |
2013-07-06 03:54 |
| [#114] CD quality no worse than High Resolution Playback After a foray into hi-rez audio, my tentative view is that the sound quality mainly depends on the recording/mastering. The formats (sacd, hi-rez pcm, etc) may contribute, but not significantly. I now concentrate even more so on good recording/mastering, regardless of format. |
A811 正式會員 218.xxx.xxx.69 |
2013-06-25 23:42 |
| [#113] CD quality no worse than High Resolution Playback 但有趣的是卻反而有發燒友不斷也去收購頭版...！ that s true |
batmanamesIA 正式會員 74.xxx.xxx.59 |
2013-06-25 23:35 |
| [#112] CD quality no worse than High Resolution Playback 表面上看音響科技的而且確進步了，業界不斷把重播規格和標準不斷推高，現在已做到改良了也完全聽不出來了。另一邊箱又出現奇怪現象，軟件市場不斷推出不同高規格Re-mastering版本的復刻版，但有趣的是卻反而有發燒友不斷也去收購頭版...！ 實際上我們在聽覺是否有真實需要新制式，還是只是商家在市場上創造需求呢? 事實上我們人類的聽覺在一二百年來並沒有大幅度進化過，而一百年來音響技術卻已大幅進步，而重播規格來看已遠超我們人類的聽覺上限了...!個人覺得像我們老一輩的發燒友聽覺卻反而随著年紀退化，規格達到我們聽力範圍以外還有效嗎? 還只是我們心理作用呢...? 其實音響最終的目的是重播音樂，沒有好的音樂，聲音重播得有多好可能也是沒有意義，有些基本的問題我們必需要深切地去好好思考? 最後修改時間: 2013-06-25 16:14:55 |
Pilotrol 正式會員 61.xxx.xxx.38 |
2013-06-25 16:11 |
[#111] CD quality no worse than High Resolution Playback  別急著判CD出局 http://www.bettersound.com.tw/2012/02/cd.html#more 最後修改時間: 2013-06-25 15:38:20 |
george1977 正式會員 203.xxx.xxx.4 |
2013-06-25 15:36 |
| [#110] CD quality no worse than High Resolution Playback 高取樣率：國王的新衣？ 數位流、高解析度與DSD是這兩年音響業最重要的關鍵字。然而，就如同大部份的音響科技，這些並不是好聲音的保證。最近看到Mix雜誌五年前的一篇文章相當有趣，跟大家分享一下心得。 http://mixonline.com/recording/mixing/audio_emperors_new_sampling//index1.html 這篇文章是在討論一篇AES（Audio Engineering Society，音響工程協會）的研究報告。這篇報告的全名是：「音響重播中加入一個CD標準AD/DA環節的可聽聞性」（Audibility of a CD-Standard A/DA/A Loop Inserted into High-Resolution Audio Playback)。測試的方法很簡單：以一部高解析度光碟播放機作為訊源，在訊源與前級之間插入一台HHB的CD燒錄機，也就是經過了標準CD紅皮書的44.1/16類比數位轉換、再做一次44.1/16的數位類比轉換。換句話說，就是把高解析度聲音降為CD規格。 http://www.aes.org/e-lib/browse.cfm?elib=14195 有加入CD燒錄機、沒有加入CD燒錄機的重播以前級的音量控制將音量調整到0.1dB的差異之內。這是一個A/B/X測試，也就是受測者按下「更換」按鈕時，有可能其實聽到的還是原來的訊號。受測者共有六十人，包括錄音工程人員、音響迷與一些有錄音相關經驗的學生等等。受測者在進行測試之前，都會經過簡單的測試，看他們是否能夠聽到15kHz以上的頻率。播放的SACD（或DVD-Audio）包括Mobile Fidelity、Chesky與Telarc等廠牌。 重點來了。在554次的測試中，共有276次受測者正確地指出自己正在聽哪個系統。49.82%的機率，就與翻硬幣決定的機率完全相同！有人會說：音響迷與音響工程人員的測試比較有代表性。很好，因為這些人正確的機率是52.7%！有沒有可能是這些人聽力都受損了呢？能夠聽到15kHz以上的人的正確機率竟然是45.3%，錯的機會大過正確的！而且，六十位受測者，沒有一位能夠每次都回答出正確的答案。 那麼，那些信誓旦旦說高解析度或是DSD較好的，難道都是信口開河？不，在這邊分享一下BBC的一個節目影片： 當聲音沒變，口型變了時，我們都會認為聲音也跟著變了！麥果克效應（McGurk Effect）指出，當我們眼睛看到口型時，會影響到我們對聲音的辨識，這說明了聽覺受心理影響甚深。當我們播放高解析度或DSD檔案時，由於我們「期望」聽到更好的聲音，因此我們就會「覺得」自己聽到了更好的聲音。 我常說我這輩子聽過最好的音響重播都是來自於CD。既然絕大多數系統的聲音解析度都還沒能挖掘出CD裡面所有的訊息，那音響迷們到底是為了什麼在追求高解析度呢？ http://www.bettersound.com.tw/2013/05/blog-post_12.html  |
george1977 正式會員 203.xxx.xxx.4 |
2013-06-25 15:12 |
| [#109] CD quality no worse than High Resolution Playback NAR 兄真是為難咗阿U哥啦！ 粒U有閱讀障礙，過目不過三行文字，咁嘅認知能力更加無法理解圖片。呢條題目佢點都係睇吾明，無謂獻世就彈遠啲啦！ 最後修改時間: 2013-06-19 22:02:18 |
faimiu 正式會員 218.xxx.xxx.156 |
2013-06-19 21:57 |
| [#108] CD quality no worse than High Resolution Playback ... WOW, now that is heavy bass, cracking the headband ! Hahahaha !!!  |
notmychartwellll 正式會員 218.xxx.xxx.112 |
2013-06-19 21:14 |
| [#107] CD quality no worse than High Resolution Playback """""what a laugh someone who cannot express properly in english had to use photos to explain his point of view."""" """""lots of posts but still does not explain whether "cd quality no worse than hi rez playback""" The U always make complaint just about anything" (1)about excessive posting of photos and (2) complaint about members including me who wrote lots of post to share healthy opinions (which everyone understood except :cpu8088) about CD vs High Rez playback. cpu, we realized you do not have the patient to read anything, and the ability to have an in-depth understanding in anything written,. I doubt there is anyone here who can assist you at all in anything. The only thing I can do for you, instead of the 3.7 surround which I suggested to you earlier so that you can check out for yourself without asking any of us whether "CD quality is no worse than High Resolution playback". The recommendation is as follows: THIS WAY, you will never have to come back to us ask us the same question ever again. We know even we provided you an answer in writing, U do not have a clue. The following "picture is worth a thousand words". This is a much simpler version than the previous (we realized you simply cannot afford the 3.7 as suggested, this is cheaper for you). This single subwoofer will definitely give you even heavier mono bass for your CD or high resolution playback. AT LEAST YOU NO LONGER HAVE TO WORRY ABOUT MIXING OR REMIXING. Do I make it clearer for you this time????  最後修改時間: 2013-06-19 21:16:16 |
NAR 正式會員 42.xxx.xxx.180 |
2013-06-19 20:59 |
| [#106] CD quality no worse than High Resolution Playback cpu, i told you bass heavy and too much headphones listenings are no good for your old brain and you never listen to any advice do you? On top of that, it seemed you never read anything in the discussion and even if you do, you never seemed to have the ability understand anything discussed between members. Can you stop making a lot of unwanted noise here and cease your brainless interruption. |
NAR 正式會員 202.xxx.xxx.42 |
2013-06-19 19:12 |
| [#105] CD quality no worse than High Resolution Playback CPU hing, the title refers to the survey done by Boston Audio society, see #1. This is published by AES. |
hkborn 正式會員 112.xxx.xxx.16 |
2013-06-19 18:46 |
| [#104] CD quality no worse than High Resolution Playback lots of posts but still does not explain whether "cd quality no worse than hi rez playback" talked about recording, editing, mixing and remixing have nothing to do with which format is better or worse. |
cpu8088 正式會員 115.xxx.xxx.214 |
2013-06-19 18:26 |
| [#103] CD quality no worse than High Resolution Playback 音樂重播最要注意平衡，音樂訊號受制於器材的質量，找出最弱一環來改善最有成本效益。 用動態範圍和頻率反應來看，重播的最弱一環是音箱及聆聽環境。音箱最佳指標是20-20kHz +/-3db,其他器材是低於+/-1db。聆聽環境噪音最高，一般有50db，這50db造成最大底噪，一般90db聆聽水平已經算高，但只有40db的動態可聽。很多錄音為了減少Clipping，只有壓縮又壓縮，音量大而動態少。 所以從重播角度來看，16/44.1已經足夠有餘，看只是看錄音水平及唱片公司是否願意製作高質素CD而已。 |
hkborn 正式會員 112.xxx.xxx.16 |
2013-06-19 16:43 |
| [#102] CD quality no worse than High Resolution Playback 談談模擬訊號如何轉為數碼檔案。 最常用的是PCM(Pulse Code Modulation)。聲音通過咪高峰轉換為電壓，而電壓的具體資料為波幅amplitude及頻率frequency。咪高峰接收的訊號微弱，要用咪前級Mic preamp來放大至錄音室常用的4dBu,約1.25V。 將電壓以數碼儲存要做取樣，在頻率來說，根據Nyquist，每秒44100個樣本確保了0-22050Hz的準確性。更高的採樣率不會令這一段的頻率更準確。無論是PCM或DSD,44100取樣已經足夠還原22kHz及以下的頻率。換句話說，在44.1KHz的取樣率下，10Hz,100Hz,1000Hz的準確度是一樣的，再高的取樣率也不能增加這些頻率的準確度。 在波幅方面，16bit 有65536層(96dB)，24bit 有16,777,216層(144dB)。電壓轉換為數碼，就是將波幅量度，放在最接近的數值。所以錄音來說，24bit有更大空間去處理混音。但是受制音頻器材，一般20bit已足夠有餘了。因為數碼化是等量劃分，無論16 bit或24bit，每一數值都會出現差異，差異再少也是差異，這些差異不能消除，但可以減少，主要是將這些差異轉移到我們聆聽範圍外的頻率，然後用low pass filter瀘去。這稱之為noise shaping。 基本上，DSD用的就是這樣的辦法來錄音的，只用1bit，但放大64倍來將差異或所謂noise轉到高頻段去，其取樣頻率也是他44.1kHz而已。最後大約有120db左右的動態。 最後修改時間: 2013-06-19 16:15:13 |
hkborn 正式會員 112.xxx.xxx.16 |
2013-06-19 16:10 |
| [#101] CD quality no worse than High Resolution Playback thanks for sharing, getting fairly technical but fun to read, push 最後修改時間: 2013-06-19 11:19:31 |
mr.paul 正式會員 116.xxx.xxx.57 |
2013-06-19 11:14 |
| [#100] CD quality no worse than High Resolution Playback Depend on the room acoustic. Whether it is a studio recording or concert recording. I try to put it in a simple explanation and hope it is easier to understand. Concert recording need 2 main hall mics at a distance away from the vocal, one spot mic for the vocalist will do. It is up to the engineer or producer to decide whether the vocal is to be recorded in pop style ot classical performance style. What about accompanied instruments that you didn't mention, if piano extra 1 to 2 mics may be needed. Again, the mix level from each mic is very important. In studio, normally vocal is recorded on top of the already prepared instruments whether virtual or real instruments which may be recorded at a different time and probably elsewhere. Voice is recorded as layers and find the best take to use. These are multi-track pop recordings and they are different to orchestral multi-track concert recordings which is a different ball game. 最後修改時間: 2013-06-17 06:22:25 |
NAR 正式會員 42.xxx.xxx.180 |
2013-06-17 06:08 |
| [#99] CD quality no worse than High Resolution Playback NAR 兄 明白了原來硬盤對錄音是這麼重要的 我猜想你所指的是交響樂錄音、、如果是人聲錄音。兩支咪 兩條聲軌(stereo,korg1000) 24/192 or 24/96 就足夠了? |
batmanamesIA 正式會員 184.xxx.xxx.162 |
2013-06-17 03:00 |
| [#98] CD quality no worse than High Resolution Playback Correction, The old SCSI 3 drive used to spin at 15,000 rpm (not 10,000rpm). No hard drive are made to spin this fast these days with the exception of some of the old SATA drive by WD, they spin at 10,000 rpm. They are no longer made today. For those fast spinning drives, their bearing used to suffer pre-mature failure or make a lot of noise when they get older. Those 10,000rpm and 15,000 rpm drives used to get very very hot. |
NAR 正式會員 42.xxx.xxx.180 |
2013-06-16 17:52 |
| [#97] CD quality no worse than High Resolution Playback hkborn hing, Oh I missed one of your questions: Indeed I started using a familiar 24/192K raw stereo mixdown file, then down convert that file using various software based sampling rate converters for comparison. The different files were saved. Hence the findings. It was another way to spend one afternoon keeping myself busy instead of a watching video or spend time in R33. 最後修改時間: 2013-06-16 10:06:01 |
NAR 正式會員 42.xxx.xxx.180 |
2013-06-16 10:04 |
