PS Audio Perfect Wave Transport es una realidad
The PerfectWave CD and DVD Memory Transport is a ground breaking new category of device. It is an optical disc reader built to extract both standard and high resolution audio from just about any optical playback medium, such as a Compact Disc (CD) or Digital Video Disc (DVD), and send perfected digital audio data from its solid state memory to any Digital to Analog Converter (DAC) made.
It accomplishes this task in a manner quite different than other CD transports and players. Using an optical ROM reader, the PWT extracts the data off any CD or DVD in bit-perfect condition without using error correction and places that data into a special version of the PS Audio Digital Lens. Once inside the Digital lens, the musical information is stored in pure form without clocks or any reference to time. The stored musical information is then retrieved by the PWT’s asynchronous fixed timing clock and output to your DAC with perfect timing and extremely low jitter through its digital audio outputs, or jitter-free through the HDMI connector.
The results are remarkable. Based on comparisons with any standard technology CD or computer based system, the PWT produces hands-down noticeably better performance for any listener on any system. This transport unlocks all the musical magic stored in your CD library and hidden from you all this time.
The PWT’s gorgeous color touch screen displays the cover art for each CD and eliminates forever the traditional track selection by number. Song titles are displayed just as they would be on the CD cover making the PWT a joy to use and own.
As technology transcends the limitations of CD’s and we enter the next evolution in digital audio playback, high resolution audio, the PWT is ready for the challenge. Without the need for a computer, the PWT plays high resolution audio files, lossless stored music, standard CD’s and homemade compilations on either CDR or DVDR with the ease and grace of a beautifully built machine.
The PWT is built to last a lifetime and will be the last optical disc reader you need to own.
A bit of history
In 1982, the first Compact Disc (CD) was released by the band Abba. The CD release of Abba’s “The Visitors” was a bold move for the band as few people had a way to playback the disc. Up until their CD’s release, recorded audio was stored on either magnetic tape or vinyl records. The idea of storing audio on an optical disc and playing that data back with a laser beam was a remarkable step forward. If you’re interested in the CD’s complete history, you can read about it here.
A quarter of a century later the Compact Disc is still the biggest portable storage medium for recorded music and data in the world, with 2.5 billion discs a year produced (falling to 1.5 billion in 2008). Most music libraries in people’s homes are stored on CD’s and these CD’s are played back on everything from the least expensive, to the most expensive CD players and transports with varying degrees of quality.
A quarter century after the CD was introduced, the first of several new moves away from the optical storage idea (of the CD) began to take shape in the form of a return to magnetic storage devices known as hard drives. Hard drives store audio data magnetically; in much the same way tapes did a quarter of a century ago.
Magnetic hard drives have several advantages over CD optical storage: they hold more music, they can store more formats at higher resolutions and they can sound better. They also have several disadvantages: they require some form of computer to access them and their outside interfaces are not designed for compatibility with high-end audio playback sources.
In the last few years digitally encoded music has taken another few steps away from the venerable CD: the creation of media libraries accessible over a network or the internet.
It is clear that technology is moving away from optical discs as a means of storage and playback, yet the vast majority of all the recorded music in the world remains accessible only from these discs. It may be axiomatic to point out that the best technologies for any category appear near the end-of-life for those categories. The best tape recorders were introduced as the medium fell out of favor. The best turntables and phono preamplifiers ever made were designed and released after the vinyl record’s heyday. And so it is with the Compact Disc player, in the form of the PerfectWave Transport.
The PerfectWave Transport Memory Player
The idea behind the PWT started with the simple realization that there is no technical reason why storage mediums should affect the quality of the music’s performance. Properly designed and executed, digital audio data should sound the same regardless of how it was stored: on an optical CD, DVD, magnetic hard drive or solid state memory. In 2006, when the PWT project began, not one of these storage mediums sounded the same when played back. By default, if none of these sounds the same, then none of these can be accurate to the original.
CD players and CD transports all sound different. Music stored on a computer sounds different than any of the other technologies for digital audio playback. These observations are shared by nearly every audio reviewer and high-end audio owner in the world, despite the fact that when examined on a bit-for-bit basis all digital audio output data is the same as the original in memory.
PS Engineers have understood, since the early days of CD players and transports, that both CD mechanisms and computer hard drives are mechanical devices trying to perform in a world of precise timing. Audiophiles have struggled to compensate for some of these problems for years: painting the edges of their CD’s green, putting expensive mats on top of the CD, damping the mechanical mechanisms and spending thousands upon thousands of dollars buying what is advertised as the latest in CD technology. Unfortunately, few of these efforts have addressed the core problems in CD playback. Instead, they are like applying a Band Aid to a wound.
The PWT is like the Power Plant of CD’s
It is, in fact, a minor miracle that a CD mechanism works at all. The mechanical devices that control the laser reading mechanism, the varying rotational speed of the disc, the wobbling of the CD and the errors that must be corrected for even the best CD’s all need separate feedback based systems to correct for their errors. While engineering marvels to be sure, these systems of error correction are themselves Band Aids and not perfect solutions.
Until the advent of the PerfectWave Transport, every CD player ever built relies on the same mechanical technologies and suffers from the same problems as every other. PS engineering realized that instead of applying better Band Aids to the problem of CD playback we needed to design an entirely new system that accepts any quality digital audio data and outputs perfect data in its place; a system that is not affected by disc, data or mechanical/optical performance issues.
To accomplish this we fashioned the PWT after the design concept of the Power Plant AC regenerator. The Power Plant concept acknowledges that we cannot control the quality of the home’s incoming AC power, nor can we fully repair its problems. Instead we simply ignore the problems, start over and generate new AC, thus eliminating the problem entirely. There is no connection between the input and the output of a Power Plant.
The concept for the PWT is very similar in that there is no connection between the input and the output of the PWT. Unlike a traditional CD transport, you are never listening directly to the data from the optical disc. Instead the data is pulled off the disc and sent to the internal Digital Lens where it is rebuilt and stored for up to three minutes and then output by the asynchronous (unrelated) clock.
You can see this for yourself on the PWT video accessible here. Once the disc is inserted into the player, you can actually remove it and the music will continue playing.
The color touch screen display
Building the perfect transport means more than just producing the perfect output. The transport should also be a joy to use and answer a higher level of expectation from its owners.
Every CD player and transport, since the inception of the CD in 1982, has included a compromised user interface. This includes everything from a simple LED display with track numbers and times, to complex color LCD’s that look like they were designed to be in a circus. None of these interfaces addresses what music lovers really want; the information that is included on the CD case.
Since 1948, when the vinyl LP was first introduced, music lovers around the world got used to reading album covers and liner notes associated with them. When CD’s came into popularity they were housed in miniature copies of albums with small cover pictures and even smaller lists of song titles and liner notes.
60 years after the introduction of the vinyl LP, there are still very few players that recognize and display cover art and song titles from the disc itself. The engineers at PS Audio determined to put this shortcoming behind us with the introduction of the PWT’s touch screen display.
Once connected to an internet capable network connection, the PWT will display the cover art and song titles of just about any CD or DVD you place into it. To do this, the PWT automatically identifies the disc that has been inserted. The PWT then communicates with PS Audio’s Global Net servers over the internet and the information for that CD is downloaded and displayed on the front panel color touch screen.
No longer do you have to have the CD case in-hand to figure out which track you wish to listen to. Simply scroll through the actual song titles on the disc itself and touch the track you wish to hear. The PWT will instantly play the selected track.
Your personal library
Every time you play a disc in your PWT a copy of the cover art and song titles are kept for you on your own private library page through the PS Audio website. Here you can manage your entire library of information.
Global Net’s ability to accurately retrieve perfect information and cover art for the millions upon millions of CD’s in the world is not perfect. Should the PWT display either incorrect song titles or cover art, it is a simple matter to access your personal library page and correct the information. Once corrected, your PWT will display the new information accurately every time.
High resolution WAV files on DVD
The future of audio is to be found in higher resolution media than CD’s. CD’s are limited to 44 kHz and 16 bits. Ask anyone in the engineering community about the inherent limitations of CD’s and you’ll likely get an earful.
For CD’s to approach and, in many cases, exceed the musicality of vinyl and master tapes, higher sample rates and bit depths are required. 24 bit, 96 kHz is a minimum for high resolution audio and even higher sample rates (up to 192 kHz) are best. The future is bright indeed with high resolution audio now entering our lives.
The first high resolution audio discs were DVDA (DVD Audio). The next attempt was SACD (Super Audio Compact Disc). DVDA failed because of restrictive licensing issues and today there are very few of them left. SACD was a format introduced by Sony and was well accepted in the high-end community. Unfortunately, Sony did not make the format public so other manufacturers and record labels could embrace it. This restrictive policy lead to the death of SACD as a possible high resolution format and Sony has since cancelled future SACD releases.
Record labels still interested in high resolution audio have since taken matters into their own hands and are using WAV (Waveform Audio Format), recorded onto a DVD, as the basis of new high resolution releases.
WAV is an uncompressed audio format for Windows computers (AIFF is the Macintosh equivalent). The advantages of WAV are many but perhaps most important is that the format is open to the public, can handle high resolution audio files easily and is being adopted by many record labels as the format of choice.
The disadvantage of WAV is that, up until the introduction of the PerfectWave Transport, you had to rely on a computer to read the WAV files from a disc or from downloads; all that has changed with the introduction of the PWT.
The PWT can read WAV files directly off a DVD and present jitter-free digital audio data to your DAC with resolution up to 24 bit and samples rates as high as 192 kHz. This is a stunning achievement for PS Engineering. The ability of a standalone dedicated transport to read DVD discs is unheard of and the PWT is the only product in the world with this ability.
To gain some further insight into the world of high resolution audio, and its emergence through the record labels as the format of choice, click here to read our newsletter on the introduction of the PWT with Reference Recording’s HRx format.
The PWT is future-proof. Through either its rear-mounted SD memory card, or through online access, the PWT’s operating system and feature list is upgradeable by PS Audio for its customers. This allows PWT owners to keep up with any future upgrade paths without returning the PWT to the dealer.
The first upgrades planned after the initial release of the PWT will be the addition of new CODECS to read compressed file formats off of discs.
All digital audio is organized in one of several formats that must be decoded to present to a DAC so you can hear the music. CD’s, for example, are organized in a format very different than DVD’s. The job of the PWT’s internal engine is to make sure whatever is on a disc can be read properly and organized into exactly the right format for the DAC.
CD’s and DVD’s can store more than just their native formats. They can be used to store different formats such as WAV, FLAC (Free Lossless Audio Codec), AIFF (Audio Interchange File Format), MP3 etc.. Many of these formats, like MP3 and FLAC are used to compress data into smaller file sizes. MP3 is known as a lossy compression, meaning they strip away valuable audio data to compress the music to a smaller file size. FLAC is a lossless compression method, meaning there’s nothing lost in the compression process.
All these formats use what engineers call a CODEC to translate files into something your DAC can use to play music. The word CODEC is a portmanteau of ‘compressor-decompressor’ or, most commonly, ‘coder-decoder’.
The first CODEC scheduled for release with the PWT will be a FLAC decoder. This upgrade will be free and available to PWT owners sometime in late spring 2009.
Inside the PWT
Given the technological wonders the PWT offers its owners, you might think that we simply took a computer and stuffed it inside the PWT chassis like other manufacturers do. Nothing could be further from the truth.
Taking a computer motherboard along with its input and output components and building a high-end product around it is, in our opinion, a compromise. No computer is designed with high-end audio requirements in mind. They are noisy environments that were never intended to produce jitter free digital audio data without digital manipulation.
The PWT was designed from the ground up with its own hardware and operating system dedicated solely to the reproduction of music.
Inside, the PWT is deceptively simple. The heart of the PWT is a 440,000 gate FPGA. An FPGA (Field Programmable Gate Array) is like a giant microprocessor that can be configured to do whatever the engineers want. It has no built-in functionality whatsoever and is hundreds of thousands of assignable cells or gates operating from a custom bit of software.
Let’s follow the path of the PWT as it extracts the data from your optical discs.
First, the ROM drive
Your disc is read from a computer style disc drive known as a ROM (Read Only Memory) drive. Unlike a conventional CD disc drive that you find in any transport or CD player, a ROM drive is completely controllable from an operating system and is independent of any standard disc extraction and error correction methods built into CD and CD transports.
The use of an independently controllable optical disc drive is a critical element in the PWT’s success. With a standard optical drive, even a great one like the Philips CD PRO2 top loader (used on only the most expensive CD players and transports), the data is read and error corrected by the mechanism itself without allowing any choice over how it is done.
Using a ROM drive, we can read the data using an entirely different approach that requires no error correction.
Our goal with the PWT was to extract the data from any optical disc in bit-perfect form without the use of standard error correction used by all CD mechanisms.
Standard error correction uses a predictive system that “guesses” what the data should be if there is an error detected on the disc. A better system reads and then rereads the data as many times as necessary until a perfect match is achieved. This read and then reread system is what the PWT uses to extract bit perfect data from the disc.
Once the data has been taken in bit-perfect form from the CD or DVD, it is sent to the PWT’s internal Digital Lens.
The internal Digital Lens
Inside the PWT there is a built-in Digital Lens.
A Digital Lens is a device that takes digital data in and focuses it down to a single perfect point at its output. The first Digital Lens was designed by PS CEO Paul McGowan and PS VP of engineering, Bob Stadtherr, back in the early 1990’s. It was released as a Genesis Technologies product and was an immediate best seller. Nearly 20 years later, used Digital Lenses are purchased almost as soon as they become available on the used market; they were that good.
The digital Lens in the PWT has three elements: an input data organizer, a 64mB memory, an output data organizer. Musical data is taken off the optical disc, fed into the Digital Lens where it is stored in memory until the output digital organizer and final clock ask for the data.
The Lens allows the ROM drive to have enough time to read and reread the data as many times as it wants and equally important, allows the output asynchronous clock to operate at a fixed and independent rate.
The output asynchronous clock
The CD player or CD transport provides the operating clock (timing) for the entire digital audio system. This clock is critical because it runs the DAC and everything else in the system.
There’s probably no place in the digital audio chain more important than this clock and, oddly enough, most high-end CD players or Transports pay much attention to it. This lack of attention to the master clock is one of the biggest sonic handicaps of all CD player and Transport ever made.
Some manufacturers have gone to extraordinary lengths to solve this problem, including external clock inputs and super accurate time bases that use atomic clocks to maintain accuracy.
While certainly effective, the extraordinary measures are expensive and unnecessary if you get the clock architecture right in the first place; and the PWT gets it right.
The proper way to build a transport is with an asynchronous clock with a Digital Lens feeding it. Only the PWT has this capability.
An asynchronous clock sounds pretty technical; it is not. It simply means that the master clock is completely independent from the optical disc reader.
In a standard CD player or Transport, the master clock is synchronized to the optical disc reading mechanism. This means you are basically relying on a mechanical spinning mechanism and all of its correction systems to give you a perfectly stable, fixed clock to feed the DAC. It does not work and it is not stable.
Here’s the problem. Optical disc readers are constantly changing the rate at which the data is coming from the disc. Sometimes it comes faster and sometimes it comes slower than the fixed speed of an asynchronous clock. If that data is coming in faster than the clock, you get a traffic pileup and the system crashes. Too slow and nothing comes out.
The Digital Lens has a large and smart memory storage buffer. It’s big enough to handle any speed variation of the optical disc reader. Because it is an intelligent buffer, the length of the memory is automatically adjusted to fit anything the optical disc reader is doing and feeds the master clock what it needs and wants. The system is really quite simple.
The results are amazing. With a fixed asynchronous clock fed by the intelligent Digital Lens, the output master clock is accurate and jitter free supplying perfectly timed data to any DAC connected. The results are immediately apparent the first time you sit down to listen. In fact, this new architecture means the use of sample rate converters in DACS is no longer necessary or even desirable.
I2S through HDMI output
There are two ways to get the digital audio data out of the PWT: standard SPDIF/AESEBU digital audio outputs or I2S. I2S (pronounced “I squared S”) is the preferred method if you have the PS Audio PerfectWave DAC that can receive it.
To understand I2S it is necessary to first understand the standard digital output, SPDIF. SPDIF stands for (Sony Phillips Digital Interface) and was invented by Sony and Phillips over 20 years ago as a simple and convenient method of transferring digital audio over a single RCA cable or optical cable. 25 years ago, when the format was invented, no one ever dreamed that a quarter century later high-end music lovers would not be happy with the compromised performance of SPDIF.
SPDIF takes three separate internal clocks along with the raw music data and combines them into one stream and sent out with an RCA, XLR or optical cable to the DAC. Once that single stream is received by the DAC it must be separated back into the multiple clock and data streams in exactly the same timing and form it started. The problem is the encoding and decoding of these complex critical clocks is never perfect. Through this flawed process we get jitter and timing error that we can easily hear.
A much better way of delivering the clocks and the data between the transport and the DAC is to not mix them up in the first place. This is what I2S does. Instead of trying to stuff these clocks and data into one stream, I2S simply transfers the three clocks and the data on separate cables to the DAC. Done in this way, there’s no chance for error or increased jitter and the audible results are simply stunning.
PS Audio has searched for a long time for the perfect cable to transfer I2S data. Some manufacturers use CAT-5 which is the cable your computer connects up to the internet. We took one look at this method and rejected it out of hand. The best solution we found was HDMI (High Definition Multi-media Interface). An HDMI cable is the best multi-conductor digital cable made today and it was the obvious choice for the PWT.
Simply use any HDMI cable between the PWT and the PWD and you are transferring data perfectly.
The last transport you’ll ever need
The PerfectWave Transport is a revolution in product development and a pure joy to use. It plays both DVD as well as CD. It finds and displays cover art and song titles on its beautiful color touch screen.
It easily handles both standard CD playback as well as high resolution audio files directly in the machine.
The PerfectWave Transport is the last optical disc player you will ever need or want.