Sound Choices

Consumer confusion, marketing mistakes, and a dearth of authoring tools accessible to mid-size producers have hindered the growth of DVD-A and SACD, but the studios behind the audiophile formats have big plans for 2003.

Which of the new audio formats is superior—Super Audio CD (SACD) or DVD-Audio (DVD-A)?
It's all a matter of opinion. For record labels, the choice may be based on technical superiority or political alliances. For the audiophile consumer who actually understands what a DVD-A or SACD is, it really doesn't matter which they prefer because it's all about which titles are available, and that number's still quite small. At year's end, there were about 300 DVD-A titles on the market and around 100 SACD titles. By March 2003, it is expected that total U.S. third-party SACD titles will be 146, plus 113 hybrid multichannel discs. Both formats started to make a little noise at the end of 2002. On the one hand, Warner, EMI, and BMG all announced or affirmed their support of DVD-A with a range of new and catalog titles; BMG's DVD-A version of Elvis 30 #1 Hits on RCA was expected to be a hot seller during the holiday season. Sony and Universal, on the other hand, support SACD. EMI's Virgin released the 22-title "Rolling Stones Remastered" catalog series in the fall, the first release to create a real stir in that format.

Still, the labels and their distributors are having a hard time figuring out how to market either format. "Retail accounts are grappling with how they retail these new formats. They finally figured out that DVD-Video is big enough to have its own music section. But high-end audio stuff is lumped together," says Leslie Cohen, vice president of business development for Sony Music Entertainment. Cohen recounts one trip to a retailer who "had DVD-A and SACD all mixed together. It's okay to be side by side, but not mixed together. The poor consumer sees this huge section, but has no idea how to attack it." Then there are the big names like Circuit City and Best Buy that support hardware, but don't know what to do with the titles, so they shelve them with the players rather than in the music section. That's not the best way to sell discs, but Cohen admits that the formats need to be proven sellers before they command their own section in the battle for shelf space.

Both formats have a long way to go with regard to marketing and acceptance. And how many engineers really are savvy enough to put out a good product? Is DVD-Audio or SACD really being produced at the project studio level—like CD-Audio, DVD-Video, and DVD-ROM—or do both formats remain, production-wise, the province of the major music studios and their minions? And when, if ever, will the ascendancy of either format justify more small outfits throwing their hats in the ring? Then there's the nagging little question of how the heck DTS fits in. EMedia will attempt to put this all in perspective.

DVD-A
The official DVD-A Web site gives this as the format's definition: DVD-A "can provide a major advance in audio performance by providing the listener with advanced resolution stereo (two channels) and/or multichannel surround sound (up to six channels) music." DVD-A can provide dramatically higher-quality stereo sound than CD with a sampling rate of up to 192kHz compared to 44.1kHz for CD. DVD-A digital sound can be delivered with up to 24 bits of data, compared to 16 bits for the uncompressed pulse code modulation (PCM) CD standard. DVD-Audio discs cannot be played on a conventional CD player, though virtually every label releasing DVD-Audio discs includes tracks in the video zones of those discs that are compatible with all existing DVD-Video players. Audio CDs will play on DVD-Audio players just as they do on DVD-V players.

DVD-A titles are trickling in from some of the majors, including Warner, EMI, and BMG. As of December, Warner had about 75 titles on the market. But independent labels have perhaps been the most aggressive in pushing the format. For example, 5.1 Entertainment's goal was to have more than 100 discs, many of them new titles, by the end of 2002. Company president John Trickett has been very vocal in the press about DVD-A's benefits and, as a result, has perhaps been more instrumental than the majors in helping to launch the format. But, like virtually all the audiophile formats from gold masters to DAT, DVD-A hasn't captured the attention of the music-buying public.

Perhaps the biggest consumer awareness problem for DVD-A comes from the "DVD" in its name. When consumers hear DVD, they immediately think video; the popular press often makes the misconception worse by continuing to refer to DVD as Digital Video Disc. Instead of fighting the misconception, DVD-A creators are starting to use it to their benefit and promoting the idea that DVD-A can offer not only an audio-experience but, like DVD-V, can offer extras. In the case of an audio disc, video can be part of the extra content.

In an effort to clear things up for the consumer, record companies have come up with yet another cousin to DVD-A, which may in fact confuse the market more. The DVD Forum has set out to create a hybrid dual-layer CD/DVD-A disc that will play in all CD and DVD-A players. A good idea, perhaps, because right now DVD-A discs won't play in CD machines. But creating a CD/DVD-A format isn't as easy as it sounds. A hybrid disc requires changes to the Red Book CD specification. Warner, however, announced its support for this format at the end of last year. Another interesting way to push the consumer slowly into the DVD-A arena is to package a CD and DVD together, as done recently by RCA with releases from the Dave Matthews Band and the Foo Fighters, although admittedly these "bonus discs" are DVD-Video, not DVD-Audio. But RCA may see this as an intermediary step toward adapting listeners to receiving music content (with or without video component) on DVD discs. At presstime, BMG could not comment on the success of these projects. While practice makes perfect, it's true that authoring DVD-A is complex, and might be another reason the format has been slow to grow. There are navigation issues associated with it, for example. Authoring tools are becoming available, however, for manufacturers of these products, and it's relatively easy to make the trans- ition from authoring CD to authoring DVD-A.

http://www.emedialive.com/Articles/ReadArticle.aspx?ArticleID=5062

SACD, the Way Forward?

At the 2003 Consumer Electronics Show in January—see the report in this issue—Sony and Philips held an SACD Event at the Hard Rock Hotel in Las Vegas. There were trippy lights. There were the Grand Pooh-Bahs of Sony, Philips, and the record labels. There was loud multichannel Big Brother and the Holding Company. And there was Sony's main SACD man in the US, David Kawakami, supplying the pep talk.

Many of us were hoping for a major announcement—the SACD format has been on the market since 1999, and CES is the big trade show of the year. Instead, we were treated to reports of incremental progress on the software front and precious little else. Even my SACD-supporter pals were scratching their heads afterward.

Kawakami trotted out the largely disproved line of free music is killing the music business. As we've reported in these pages, and online, several independent studies have linked the MP3 file-swapping habit with an increase in CD purchasing. But even if these studies are anomalous, we do know one thing: music fans aren't likely to buy what they haven't heard, and these days they don't hear a lot on the radio that they want to buy.

The "free music is the problem" point of view glosses over entirely the major reasons that sales are down: high priced, low-quality music, competition from video games and DVD-Video (both Sony strongholds), and rising resentment toward the music industry and copy restrictions. In this scheme of things, free music is almost beside the point. But to Sony, free music is apparently the problem.

Kawakami then said that, similar to the way CDs rescued the music business from a slump 20 years ago, SACD provides the opportunity to save their bacon again today. Let's take a look at this reasoning, and sort out what Sony is probably really after here.

I hardly think free cassette swapping was the problem in the early 1980s. Twenty years ago, the CD represented a major and easily perceived step forward in convenience, durability, and high-tech coolness. Twenty years later, adding Super Audio to the name, and more bits, more audio channels, and watermarking to the disc is nowhere near as revolutionary a leap as what kick-started the CD in 1983. The first CDs looked very different, and clicked instantly in buyers' minds: the future was here. Although most audiophiles considered it a sonic step back, CD survived because it was obviously so much easier to use and more portable. One format could play in the home, car, airplane, and gym.

Kawakami said he hopes the public will embrace SACD because it represents better sound quality. What I'd like to hear is how they plan to ignite the mass-market interest in sound quality. MP3 has proven that plenty of music-lovers would rather listen to second-rate free audio than pay record labels for quality.

Sony and Philips will probably never confirm this in public, but in my opinion, SACD is primarily about generating new licensing fees for their bottom line and a new way for record labels to restrict how you use their content. Remember, it's copy protection for the labels, but content restriction for consumers. Audio quality may rank first as a PR tool, but in the corporate scheme of things I suggest it runs a distant third.

Perhaps Sony's biggest spin job was announcing that 2 million Rolling Stones SACDs have been sold. However, these discs make no mention of SACD anywhere on their outside covers, and were sold almost entirely to fill the need for a decently remastered Stones CD catalog—the original CD versions were horrid-sounding and incomplete. My guess is that part of the deal with ABKCO (the label that controls the first 22 Stones albums) to include the SACD layer was that the cover could contain no mention of the format, for fear it would scare off customers.

But the big news at the SACD Hard Rock event was that Sony will release 15 Bob Dylan discs on SACD, and EMI will issue Pink Floyd's Dark Side of the Moon in surround sound. That was it. Okay, and Universal will release some Police and Peter Gabriel titles, and a few assorted others. I know there are those who think SACD has "won" with this announcement, but the facts are these: In three years, fewer than 1000 SACD titles have been released worldwide, and only a relative trickle from the other major labels is planned. I was decidedly underwhelmed.

What I wanted to hear was news of a full-bandwidth, multichannel, unrestricted digital DSD connection. You'd think that by now, after three years of "major push," and all those brilliant engineers working at it, SACD would have a digital connection sorted. Nope. Sony hardware is obviously still at war with Sony software about how to keep that content locked down.

How about Sony Music announcing, to show their commitment, that they will issue all new releases as CD/SACD hybrids? Or just a guarantee that their SACDs will all be hybrids from now on, so that audiophiles can at least play them in their cars, too? Nope. But Kawakami did mention that the Terre Haute pressing plant will start rolling out 15,000 hybrid discs a day.

Or how about SACD capability for computers, so that the growing numbers of desktop and laptop music systems can play back and make mix discs from SACDs? Nope. In fact, Sony Music's own CD-restriction ploys have made many of their CDs unplayable in Sony's own computers. With SACD, they're fighting progress and the will of the market even harder.

Or how about a real surprise—like a few Sony or Philips players going universal and adding DVD-Audio playback? After all, when faced with the inevitable, Sony did eventually start making VHS machines. But for now, Sony and Philips customers will just have to buy two machines if they want to hear Neil Young's Harvest or Linkin Park's Reanimation in hi-rez audio. Quite a few manufacturers have figured out that consumers don't like being forced to choose sides in format wars. Those customers will buy up universal machines from Pioneer, Yamaha, Integra, Lexicon, Marantz, Onkyo, Denon, MSB, McCormack, Linn, and others.

Or how about addressing an issue brought up by Mitchell Gusat on our website's "Soapbox": Since copyrights do eventually expire, do the various restriction and watermark technologies also expire at the appropriate time? Or will SACD data be locked up in perpetuity?

One final request: Please provide us with a label that clearly identifies the source format and mastering path for each SACD. We know that most discs don't start as DSD masters, but we should be able to determine the format path a disc took before it ended up as an SACD, be it analog, PCM, or DSD. When sourced from PCM, sampling and bit rate should be included as well.

Before the hate mail ensues, understand that no one here is bashing SACD—unlike some folks, who want to drop the shiny discs altogether. But as currently configured and marketed, SACD is not about giving customers what they want; it's about pushing the corporate agenda onto customers. Which is why, in 2003, it ain't gonna fly. After his keynote presentation at CES, even Sony's COO, Kunitake Ando, speculated to journalists that record labels may not have a future as a result of the Internet. "When you have a problem like this, I really wish we were a simple hardware company."

http://www.stereophile.com/asweseeit/812/

Digital Evolution -- Part One

I originally formed the idea for "Surrounded" after becoming convinced of surround sound’s ability to create a better musical experience in the home. Coming to this realization posed what I thought would be considerable obstacles, from both philosophical and logistical standpoints. I mean, I’m an audiophile, and you and I both know that we audiophiles can be slow to change our long-held beliefs.

The philosophical speed bump turned out to be quite easy to overcome. If I could have better sound, which equated to more musical realism, which lead to more enjoyment, I could suppress any feelings of nostalgia for two-channel-only audio. In this instance, my logical self quickly won out.

The logistical issue was one I had partially addressed when adding home-theater capability to my system. Of course, multichannel music requires arguably even more precise speaker placement and greater system resolution, so it was not accomplished without planning and a considerable financial outlay. But I came to find that the promise of better music in the home conquers almost any tradition, budgetary consideration, or décor issue -- as many of you already know.

Just when I thought I was home free -- "I’d made a seamless transition," I thought to myself, "like a well-designed crossover, heh, heh, heh..." -- another obstacle smacked me in the head. I didn’t have the technical knowledge to really communicate to our readers the finer points of multichannel music and the high-resolution formats. Sure, I could listen and from that standpoint things were clear, but I wanted to keep pace with the technical aspects, too. It’s a good thing a writer has his sources, or resources in this case.

Thus was born the idea to develop a primer for digital audio that would take us through CD and into both DVD-Audio and SACD. The goal is not to declare a winner, but define the participants. So, armed with a desire to understand the two principles in the high-resolution multichannel-music arena, I enlisted the fine gentlemen at Switzerland-based Anagram Technologies to help. Anagram Technologies, for those that don’t know, is a Swiss company that provides digital solutions to some of the brightest manufacturers in audio. These companies include Cairn, Audio Aero, Camelot Technology, Audiomecca, Talk Electronics, and Nagra, just to name a handful. Orpheus Labs -- a company wholly owned by Anagram’s principles -- and maker of the very fine Orpheus Two multichannel preamplifier, has benefited from their knowledge base as well. And with that, off we go into our conversation with Florian Cossy and Thierry Heeb.

Jeff Fritz: For those not familiar, please tell us about Anagram Technologies, Orpheus Laboratories, and your background in electronics design.

Florian Cossy: The Anagram story is, first of all, a story of friendship between Thierry Heeb [Anagram Technologies’ DSP engineer] and myself. We have been friends for about 13 years now, both having related university cursus [degree] -- Thierry is a mathematical engineer and I am an electrical engineer. We both had the opportunity to work as consultants for Goldmund back in 1996. As time progressed, we agreed less and less with Goldmund’s "philosophy" and we decided to create our own company. Anagram Ltd. was born.

The goal of this first company was to provide innovative A/D and D/A conversion solutions to the high-end-audio domain. We developed the ATF module and then found a customer base -- Audio Aero and Cairn were the first ones. What is really funny is that Goldmund has never been a customer, even though they have tried our A/D and D/A solution and found it outstanding!

We were not able to do it all ourselves and we decided to expand. In May 2000, Reynald Gentizon became the third person to join the company as a partner, and we decided to change the structure of the company: Anagram Ltd. became Orpheus Laboratories Ltd. and we created Anagram Technologies Inc. The goals were quite different: Orpheus Laboratories was used as a demonstration brand for Anagram Technologies’ solutions, so that our potential customers would have working units to evaluate. Daniel Oertli joined us in late 2000, and he is the last partner in both companies.

Orpheus is today growing and seems to interest audiophiles all around the world. That's why we have developed an entire system with even more new products due to be announced this year.

Anagram has also grown a lot since 2000. We now have many different types of customers -- high-end audio, mass-market audio, semiconductors, and even automotive companies. Some of them do not want to be named. We are seven people, and we will be nine by April 1, 2003. The goal today is not only to provide solutions to high-end audio manufacturers, but also mass market -- not only in the audio domain but also in the video and measurement domains.

Today, we are trying to separate both companies in order to clarify for people what we do.

JF: As a beginning to our discussion on the high-resolution digital formats -- namely SACD and DVD-Audio -- can you breakdown the concept of the CD?

FC: A CD can be seen similar to the LP for the mechanical construction: You have a spiral track that covers the disc itself, between the diameters 50mm and 116mm, of the 120mm disc. The track pitch is 1.6 micrometer.

CD has a table of contents in which you have the position of each track -- from a logic standpoint (not physical) -- and the length of the track. This can be seen as similar to the index of a book.

Data is stored with redundancy, which means that when the pickup reads the data, there are control bits that confirm a correct reading (checksum bits for example¹). If the reading has an error, the decoder will either have enough information with redundant bits to correct it or it has to use an algorithm to place missing information in the datastream.

JF: How, mathematically and from a physical-structure standpoint, is the maximum resolution of a CD determined?

Thierry Heeb: First of all one has to understand that the CD is a digital media. That is, all the information on the CD can either be expressed as a "1" or as a "0." There are no in-between values possible. This fundamental piece of information is called a "bit."

As with any digital media, a certain number of bits are grouped together to form a significant piece of information called a "word." According to the Red Book (i.e., the specifications for the CD format), a word is formed of 16 bits. One 16-bit word represents a sample of one audio channel. There are two audio channels on a CD.

The sampling frequency of the CD is specified to be 44.1kHz. To state it simply: CD is encoded as 16-bit PCM at 44.1kHz. (For more information on this, please refer to the answer to the next question.) Each bit on the CD is represented as either a small hole or a small bump (depending on its value of 0 or 1) that will deflect the laser differently allowing the recognition of a 1 or a 0.

Let’s dip deeper into the matter of CD resolution. With 16 bits per word, you can actually code 2¹⁶ which equals 65,536 different values. Imagine having 16 LEDs, and each of them can be turned on or turned off. The first LED will give you two choices (on or off), the same for the second LED, and so on up to the 16th LED. So we end up with 2 x 2 x 2 x 2… (16 times), which calculates to 65,536 different values. But how does this relate, first to numbers, and then to an analog audio signal?

Let us put a numbering value (N) on the 16 bits described above. Let us call each bit B0, B1, up to the 16 bits in the word we are considering, according to the following formula:

N = -B15 * 2¹⁵ + B14 * 2¹⁴ + B13 * 2¹³...+ B2 * 2² + B1 * 2¹ + B0 * 2⁰

This gives a univocal [unambiguous] mapping of our 16 bits to the number range -32,768 to +32,767. This number range can then be mapped to an analog voltage with proportional values. This is indeed what a D/A converter does. If we imagine a 4V output signal, -32,768 would correspond to -2V, and +32,767 to +2V, and 0 would correspond to 0V. Intermediary values are mapped linearly, correspondingly.

As can be seen from the above, the smallest signal variation that can be coded on 16 bits is equal to 1/32,768 x full scale. In other words, we have a resolution of 1/32,768 with a 16-bit coded signal, which corresponds to about -96dB THD+N, as each bit represents about -6dB.

In comparison, whereas a 16-bit signal has a precision of 1/32,768, a 24-bit signal has a precision of 1/8,388,608, or 256 times better than 16 bit.

There are methods to enhance the apparent resolution of CD past the theoretical 16 bits. These techniques are either based on dithering or noise shaping. Dithering acts by adding a pseudo-random low-level signal to the audio to be coded. This pseudo-random sequence cleans out the quantification noise (truncation of a value to 16 bits). Noise shaping, on the other hand, works by moving unwanted noise to less-critical parts of the spectra. Indeed, with those techniques, it is possible to get more than 16 bits of resolution on part of the spectrum of a 16-bit coded signal.

JF: Give us a synopsis of PCM audio, its benefits, and limitations.

TH: PCM stands for pulse coded modulation and is based on Shannon’s Sampling Theorem.

Shannon’s Sampling Theorem states that a stationary and band-limited signal can be exactly reconstructed from its samples, provided the sampling frequency is higher than twice the maximum frequency present in the signal.

A good analogy to PCM is a movie track. The movie track is made of a succession of still pictures (at about 24 images/second). One can consider each of these pictures as a sample of the movie -- it’s like taking a still picture 24 times per second. When the movie is projected in a theater, what is projected is indeed the succession of the still pictures. The pictures’ change rate is high enough that we perceive the image as moving continuously in time. Indeed, the movie picture is an excellent example of a sampled system.

There is one major difference between the movie and PCM audio: The still picture we were describing is made of analog pictures in the sense that they are recorded on film. Imagine now that we are scanning those pictures into a computer. We tell the computer to use a certain resolution, say for instance 640 x 400 points. This means that the image will be cut into 640 rows and 400 lines, producing a large number of little squares (pixels) and the image will be constant on a given pixel. Think in these terms: We replaced the analog picture (without pixelization) with a digital picture with a given resolution (the pixel size).

So let us link this analogy to audio, and PCM in particular. We start with an analog signal.

First we start by taking "still pictures" of the signal at a high rate. This is the process of "sampling."

Then we "pixelize" the audio creating "still pictures." This is called quantification (i.e., we choose the resolution of the signal (16, 20, 24 bits) and associate the corresponding numerical value).

The number sequence given by the sampling and quantification of an audio signal as described above is the PCM representation of the given audio signal.

Benefits of PCM

• Easy to understand when compared to more sophisticated modulations such as PWM, DSD, et cetera.
• Natural way of expressing an audio signal.
• Linear by nature.
• Easy processing of PCM-coded signals.
• Very large PCM-compatible digital audio gear in the field.

Limitations of PCM

• Limited bandwidth (at least with 44.1kHz or 48kHz) for transient reproduction.
• Non-suitable for direct digital amplification.
• Loss of phase information in the higher part of the spectrum on short signals.

In part two we’ll delve into the DVD as a storage device for SACD and DVD-Audio, and discuss Meridian Lossless Packing (MLP) and Direct Stream Digital (DSD).

http://www.soundstage.com/surrounded/surrounded200304.htm

Making Compact Discs

The compact disc has become one of the most familiar objects in electronics, but although the iridescent little discs are everywhere, few people really know how the shiny things come to be.

Or so it appears. I read an explanation recently, in which the writer had a laser burning data into a thin metal disc, which was then bonded between a couple of sheets of plastic to make the final product. It is true that lasers are used to make the original master, and certainly lasers are used to play CDs, but they form no part of the process of manufacturing a commercial compact disc.

So here’s how it’s done. The same techniques are used with other optical media, such as the various forms of DVD.

A CD starts out as a digital tape recording, in which strings of 1s and 0s -- the binary digits, or bits -- are recorded as on-off pulses. The master CD is created by focusing a very fine laser onto a glass disc coated with photosensitive material. As the laser is moved gradually across the surface of the spinning disc, from center to edge, the pulses on the tape switch the laser on and off. When the laser is on, it exposes the surface of the disc like a piece of photographic film.

After the completed disc has been "developed" like a photo negative it is given a chemical wash that has no effect on the areas that were not exposed by the laser, but which dissolves the coating where there was exposure. What's left are a series of depressions, or pits, where the laser hit the surface during the mastering process. These microscopic pits form the digital code your CD player will eventually read.

A thin coating of nickel is now plated onto this pitted surface. When it is sufficiently thick to hold together, it is carefully peeled off the glass disc. Its surface is the reverse of the master: where there were pits, there are now bumps or ridges representing the digital data. This metal "father" could be used as a mold to make the final discs, but this is usually only done for very small runs. Instead, the negative father is used to create a number of plastic positive "mothers" that go through the same plating-and-peeling that the master did. The result is a number of negative "stampers" that are used to press the final discs. Each stamper can make between 5000 and 10,000 compact discs.

The process, if you hadn’t noticed, is in essence the same as for making vinyl LPs, even down to the terminology.

Stampers are tested in various ways before they are used. They are spun on special turntables to remove any eccentricities before the central hole is punched. They are inspected microscopically to detect any physical flaws. They are even played on special machines that can read the data in this reverse form.

If all is well, the stamper is inserted into a special injection-molding press, which forces melted polycarbonate into the surface under very high pressure: 25 tons. The result is a transparent disc perfectly flat on one side, and with an impression of the original master's pits on the other.

At this stage, all the digital information is present, but the disc can't be played because there's nothing for the CD player's laser to bounce off. To remedy that, a very thin coating of reflective metal is applied to the pitted surface. Usually it's aluminum, but some specialty labels use gold because, unlike aluminum, it will not oxidize and become cloudy and non-reflective even if exposed to air. To protect the reflective layer, a thin coating of liquid lacquer is applied to the surface and then dried and hardened under ultraviolet light.

Finally, the label is silk-screened onto the lacquer layer, and the disc placed in its package. All these operations are done in a super-clean, dust-free environment.

One of the main misconceptions about the CD, even among quite knowledgeable users, is about where the digital information actually is on the disc. Intuitively we would expect it to be on the "playing side" but in fact it's impressed into the label side and sealed under the lacquer coating. The laser reads the data by passing through the transparent disc and reading what's on the other side. Because of this, it's very important that you protect the label side of a CD when handling it; the smooth playing side is much more robust.

Many people ask why CDs are only recorded on one side. There's no technical reason a two-sided disc couldn't be produced; the DVD uses exactly the same technology and there are indeed dual-sided discs available (achieved by gluing two single-sided discs together back-to-back).

One reason is that the second side is needed for the label. The other is that, at 70-plus minutes playing time, there's no reason to make it any longer. There's a (possibly apocryphal) story that the 73-minute nominal length was chosen by a Sony executive because that's the length of Beethoven's 9th Symphony, and he felt that it should fit on a single disc.

http://www.mastersonaudio.com/features/20031015.htm

The Case for NOT going above 0 dBFS For Digital Playback Systems

I first became aware of this issue back in the early 90's when I was testing a DAC that used a Burr-Brown Digital Filter and D/A Converter. I observed that the 1kHz square wave test from CBS CD1 test disc was being clipped. I knew that the analog low pass filter had plenty of headroom, so I decided to contact Burr-Brown and speak to an applications engineer. When I explained to the applications engineer exactly what I was observing he remarked that this test went over the 0 dBFS limit and was clipped by the digital filter. He also remarked that this was an "illegal state" and nothing should go over 0 dBFS. He also bluntly stated that this was a "stupid test". Twelve years later and that Burr-Brown applications engineer is still right.

In the AES paper titled 0dBFS+ Levels in Digital Mastering by Nielsen and Lund are a number of examples as to what happens when the recorded level goes above 0 dBFS. If the signal is not clipped by the digital filter, and goes above the 0 dBFS level than the signal exhibits gross distortion. A well designed CD player or DAC will have -90 db THD + N or better at 0 dBFS. When you go over that the distortion can easily be degraded by 50 to 60 db. It appears by the numbers and what many of us are hearing is that Linear PCM, just like any other system can be overloaded.

Given the present mentality of the ever obnoxious louder is better crowd, allowing more headroom in digital filters will only cause recorded levels to be pushed even higher until they reach the new limit. This is starting to remind of that one great scene in Spinal Tap, where the guitar player points to his Marshall stack and proudly proclaims that his volume dial was changed so he could turn it up not to just 10 but 11.

There is one last issue that concerns me. The typical voltage coming out of our players at 0 dBFS is typically 2.0 to 2.2 Vrms. Power amp sensitivity can be anywhere from 0.5 Vrms to 1.5Vrms with gains typically from 26 db to 32 db ( Av = 20 to 40). Pre amp gains are typically 6db to 18 db (Av=2 to 6). As we can see from the gains presently used in consumer audio 2.0 Vrms is already high and is pushing at the limit, and with the hyper compression we will find ourselves at the very lower limits of our volume controls with small changes in volume producing very non linear results. If this is pushed higher, than standard systems will have to have adjustable gains to incorporate the higher output from the players. I don't think the rest of the industry is going to have a very positive view on this to put it mildly. For those of us who listen to classical and pop we will now be faced with resetting gains for different program material. For Home Theater users whose speakers are typically 90 db spl the problem is further exacerbated due to the higher efficiency speakers.

Given all of the evidence above I see only greater distortion, and aggravation for consumers and music lovers if recording levels are continually abused and taken to beyond their designated limitations.

http://www.audioholics.com/education/audio-formats-technology/the-case-for-not-going-above-0-dbfs-for-digital-playback-systems