DVD Audio & SACD - The Royal Scam Part I

Original Publish Date: 12/23/01 - Much of the content in this article has been addressed via hardware, but we keep it live for archival purposes. Software selection however is still the big issue remaining.

Introduction
The Audio-World has been full of hype and marketing gimmicks since its inception. Just take a glance at the cable industry and some of the manufacturers wacked out claims and it is easy to see. Hardware manufacturers are always looking for newer features to add to their product lines with hopes of boosted sales by sometimes creating the false consumer need for newer technologies even if they have little or no practical usage in the real world or if their implementation limitations hinders their true potential. To an extent, this is the case with DVD Audio and SACD. While many audio publications have recently been writing glorious reviews on these new players that supposedly offer superior audio playback to CD, they often fail to tell you many of the shortcomings that currently make these technologies less than practical or ideal for that matter.

Comparison of the Technologies
For those of you that may not be familiar with the lingo, let me simply define them as follows:

DVD Audio
Next Generation of DVD that is intended to replace the CD. It is based on a higher data rate than CD or DVD Video and is backwards compatible with both. DVD Audio allows for variable data rate allocation for up to 192 KHz / 24 bit 2 CH audio or 96 KHz / 24 bit Audio for front 3 Channels and 48 KHz / 20 bit Audio for the 2 rear channels and many permutations of sampling rate and data rate so long as the total data rate does not exceed 9.6 Mbps. DVD Audio standard provides for a lossless data-compression method called MLP.

MLP
Meridian Lossless Packing is the proposed standard decoding method for DVD Audio. It allows for substantial reduction in the amount of data that must be stored on a disc and in the rate that it must stream off the disc, which in the DVD Audio case cannot exceed 9.6 Mbps. MLP allows exact bit for bit reconstruction of the original uncompressed signal on playback, allowing for the ability of 96 KHz / 24 bit audio for up to six channels simultaneously.

DVD Video
Current popular DVD format which is very similar to DVD Audio but is data rate limited to 6.4 Mbps. It uses a lossy compression systems that discards unused data (such as Dolby Digital and DTS) to decode multi-channel surround sound.

SACD
Sony / Phillips proprietary audio format only, backwards compatible with CD, and intended to replace the existing CD format. It is a high sampling rate system with 1 bit resolution of 2.8 Mbps. It uses low bit rate allocation with a much higher sampling rate that DVD Audio to linearize noise quantization and dither issues inherent in 1 bit systems.

Obviously these new formats are superior, at least on paper, to CD's limited 44.1 KHz / 16 bit 1.411 Mbps capability and may edge out DVD Video. So why isn't everyone turning in their existing DVD / CD players and software, and running out to buy these prospective formats? To put it mildly, these technologies may be great, but their implementations are extremely flawed and limited.

DVD Audio & SACD I - The Royal Scam - page 2

Issue #1 & 2 No Universal Digital Output & Limited/No Bass Management
I might as well kill two birds with one stone. These first two issues are perhaps the most critical of all, in my opinion, as they severely undermine the benefits of these technologies. Currently, in order for us to enjoy a DVD Audio or SACD disc, short of buying a costly proprietary solution from Denon, Pioneer, or Meridian, the special player must be connected to your Receiver / Preamp Processor via six analog RCA type connectors (seven if a discrete rear center is included).

Connection Diagram for DVD-A/SACD Player to an AV Receiver (analog connections only)

Since very few Receivers / Processors have bass management via the analog inputs, you must rely on the DVD-Audio / SACD player to handle the bass management. This would be fine, except that only a few of the current DVD Audio or SACD players have bass management out of the analog outputs for DVD Audio or SACD signals. In fact, those that do, usually have limited bass management capabilities in that many of them have a fixed crossover setting between 100-120H, and/or the bass management may apply only to DVD-A or SACD on hybrid players.

The internal bass management circuitry for a majority of these players, which is usually mediocre as best, usually only accommodates DVD Video Dolby Digital / DTS decoding. That being the case, you must realize at this point that if you are reliant on the DVD/SACD Player or your Receiver / Processor to handle the bass management for DVD Video Dolby Digital / DTS, and have bypassed the LPF of your subwoofer, you will be sending full frequency range to all your speakers, including the subwoofer anytime you decide to listen to DVD Audio or SACD software via the 6 channel analog connections. This is especially deterimental since many DVD-A/SACD discs are mixed for six full range channels, as per the specifications of these formats. Thus there is no hard requirement for a dedicated LFE channel, and thus the sixth channel is often used as an overhead channel meant to be placed above your head in a centralized location. This can basically cause a serious compatibility issue with your current 5.1 system as most of us use that channel for a dedicated subwoofer. I find this most problematic on one particular DVD-A disc from Toy Matinee. I realized this when I heard vocals and cymbals coming out of my subwoofer. The sixth channel appeared to be used as some sort of ambient overhead center channel which of course my system, as well as the majority of home theater enthusiasts systems, does not support. Because of these bass management issues, you may need to go behind your subwoofer and enable the LPF each time you listen to the DVD Audio or SACD format and pray that the other 5 or 6 channels will not be overloaded by the full frequency and dynamic range of a bass management-less system. Even worse, if the sixth channel is not mixed for LFE, you will have to connect another speaker in your system and place it God knows where, or disable your subwoofer completely. For more information on bass management, please see our many articles written on the topic.

So why aren't the majority of audio magazines explicitly telling you this? Perhaps they haven't yet caught on to some of the pitfalls of this new technology. Or maybe they just don't want to frighten you or cause their hardware manufacturers who advertise in their magazines any grief. Well that's why we are here. Listen to me now and believe me later: Don't Buy Into It!

The politics of the DVD Working Group and the Record Industry are as full of bureaucratic nonsense as the ADSL Working Group and RBOC's, and as you may know this has certainly caused considerable difficulty for the DSL industry.

My point is, all of these issues would dissolve if the powers that be would get together and allow the higher bit rate signals to be digitally transmitted via IEEE Firewire or equivalent. This would allow the Receiver / Processor to handle the bass management, digital delay compensation and decoding in the digital domain, as it rightfully should be. The politics of the DVDWG buttressed with the agenda of the Record Industry may actually cause the demise of these new technologies before they ever fully launch into the consumer marketplace, which brings me to issue #3.

Issue #3 Scarce and Expensive Software
If DVD Audio / SACD are intended to replace CD, they are not going to accomplish this by offering a handful of mediocre selections at prices in excessive of $25 per title. The average music listener hardly has the disposable income to afford the hardware, let alone additional $10 cost for these titles as compared to current CD's. And more importantly - where are the titles by popular artists we all love?

The Advantage of DVD Audio / SACD with Respect to DVD Video is:
Fidelity at best, perhaps nothing at worst, at least with the way these new technologies are currently being implemented and marketed. While there may be audible advantages to higher sampling / data rate audio streaming, it may not be realized by transporting the data via analog with no bass management or digital delay compensation facilities. The Signal to Noise Ration (SNR) of DVD Audio is a whopping 144 dB (6db x 24bits).

Currently the best microphones on the planet fall shy of this number by at least 20dB or so and most current so called 24 bit audio DAC's don't deliver anything better than 114 dB (or 19 bits) of resolution after the analog conversion. There is some advantage here, perhaps about 3 bits or 18dB lower noise floor than normal CD, assuming the hardware (amps) included, are quite enough to benefit.

The threshold of human hearing is about 20 kHz and thus a minimum of > 2x the bandwidth or 44 KHz (Nyquist Criteria) should provide adequate linear frequency response after going through oversampling and a digital brickwall filter, for us humans. However, in practice, according to Engineering experts experienced in active noise control they have seen that amplitude and phase (especially phase) become ambiguous above 1/3rd the sampling rate, which for the 44.1 KHz sampling rate would be 14.7 KHz and up. This implies that a minimum sampling rate of 60 KHz is required to properly reproduce the 20 KHz bandwidth of perfect human beings. So, I suppose I can see some benefit in choosing a higher sampling rate. The word length or # of bits may make a notable difference however. 24 bits provides significantly more resolution than 16 or 20 bits and thus allows the restoration of the waveform to appear more like the original analog signal. However, most recording studios master mixes in 16 bit or less because of hardware limitations. Thus, many of the DVD-A and SACD discs on the market are just re-mastered into 5.1 channels from either the original analog tapes, or 16 bit recordings. So unless the recording is fully mastered on 24 bit equipment for DVD-A, or 1 bit DSD equipment for SACD, the full potentials of these formats cannot be realized.

While I do feel DVD Audio and SACD offer potentially better sound than current DVD Video or plain two channel CD, I believe the differences are subtle to moderately dramatic and would require a very revealing system properly set-up, a well recorded and mixed disc, and keen audiophile ear to appreciate it. I suspect DVD Video and CD will satisfy 95% of the consumer marketplace, and that the audio quality will improve with time, as the recording and mixing processes get better. The sad reality is most consumers are content with compressed MP3 and/or Dolby Digital, thus making the case for high resolution formats such as DVD Audio and SACD somewhat limited to a niche market of audiophiles and enthusiasts.

Is there room in the marketplace for DVD Audio and SACD?
Maybe. But it will be a long uphill battle provided by endless challenges should the three issues I discussed (1: No Digital Output; 2: No Bass Management; 3:Scarce Software) realize no immediate resolution.

Until then, as always - enjoy the music!