Preamble After more than 20 years, we finally understand how all problems of CD audio are originating from CD's analog and mechanical aspects. Analog? Philips and Sony and all their followers always told us that CD is digital and has perfect sound forever!

If this is/was true, why do all kind of tweaks in the analog domain make such great differences in the perception of the reproduced music? Stop Light applied on the edge of a CD; circumcising the edge of the disc; various clamping techniques; all kind of polishing compounds and fluids; various power supply enhancements; demagnetizing and of course the subject of this article, making a completely new copy of a disc - all these adjustments are 100% analog and most are actually mechanical. To get a better understanding of how and why these tweaks and improvements work, we must take a closer look at CD and its inner workings.

Analog The inventors of the CD did an incredible job. The amount of work that has been put into the creation of this medium is enormous. It is said that the error correction mechanism took 10 years of research alone. Many people believe the result of all this effort is a digital representation of the analog waveform. Simply put, this assumes that all the 1s and 0s on the disc result in the original waveform when converted through a DAC. Any dropouts due to minor scratches are fully recovered by the error correction system. Only the worst cases create audible hiccups when a scratch is too big. Unfortunately, this image of the workings of CD is not entirely correct. The CD only carries a part of the digitized analog waveform and even that part is

only a representation of the actual waveform. First, only the amplitude information is encoded on the CD. The other part of what makes up a waveform -- the time domain information -- is not represented. When you see a normal sine wave, the vertical axis represents amplitude or power while the horizontal axis represents time. Together, the information of time and amplitude creates a tone. With a CD, the time portion is considered to be a constant. A clock provides timing cues at a constant rate. The same clock frequency is used for disc recording and playback. With each clock 'tick', the CD player should read one sample. This idea is perfectly acceptable in a perfect world.

Alas, we don't live in a perfect world - but let's assume we do for a moment. CDs encode amplitude information in pits. Contrary to popular belief, a pit does not represent a digital 1. CDs work on such a small scale that a string of ever-changing 0-to-1 and 1-to-0 transitions would be nearly impossible to read correctly. What happens when a word ends with a 1 and the next starts with a 1? Where does one sample end and the next begin? To counter this problem, the engineers at Philips and Sony introduced a modulation technique called Eight-to-Fourteen. In EFM, every possible 8-bit word -- the length agreed upon for the RedBook standard and ranging from 0000 0000 to 1111 1111 -- has a 14-bit equivalent. These 14-bit equivalent words are generated such that there are always more than two but less than ten consecutive zeros. The result? Information stored on a CD is never shorter than 3 bits or longer than 11 bits. These pit lengths are called T3 to T11. The transition from pit to flat is now easy to track to represent the amplitude information of a waveform.

Like the groove of an LP, CD stores all of its data in a single string. This string of data consists of the already mentioned EFM words in the form of pits and flats plus the so-called sub code. The sub code carries information about the laser location to enable track selection. The Table of Contents or TOC code directs the laser to the correct spot on the disc (we'll see later that 'correct' can vary). Besides the sub code, CD protocol requires a synchronization prompt, which is inserted into the string at various places. This synchronization word helps to regulate the CD player's drive motor.

Unlike an LP, a CD does not spin at one constant velocity. As you can imagine, the start of the spiral 'groove' near the hole at the center of the CD is much shorter for one revolution than the end of the groove near the outer edge. RedBook specifications demand constant linear speed. To achieve that, the CD spins faster at the beginning of the spiral track and slows down gradually towards the outer edge. The rotational speed thus varies from 500 to 200 rpm.

Back to the representation of the waveform. We have seen how the analog waveform is converted into a bitstream of 1s and 0s and then into EFM words that are translated into pits. In the process of creating a physical CD inside a dust-free clean room, a high-tech laser burns the pits into a layer of photo resist applied to a meticulously cleaned glass plate of 240mm diameter and 6mm thickness. The laser is called a laser beam recorder and is fed by the output of the mastered audio recording. While laser- burning the photo resist on the glass plate to create the spiral track with its 0.6 millionth/meter-wide pits, this beam recorder can burn up to about 2 billion pits.

The next step develops the glass disc now called glass master just like a photo by etching away the exposed parts. All manner of laser equipment controls this process because pit depth should be neither too deep nor too shallow to conform to standardized refraction values. After the etching is completed, a process called electroforming deposits first a film of evaporated silver onto the photo resist layer, then adds a coat of nickel atop the now silvered glass master. Next our CD fabricator separates the nickel layer from the glass master and removes any photo resist material which results in the metal master or 'father' from which several positive 'mother' images are generated which lead to further negative impression stampers called 'sons'. Their use depends on the size of a run. A short production run may rely solely on the original father while large-scale duplications use the son clones/copies.

The next step injects molten polycarbonate into a stamper to produce a 1.2mm thick disc with a pitted spiral track upon which a 50 to 100nm-thick layer of aluminum, silver or gold is applied to create reflectivity for the laser. This is finished up with a thin protective acrylic layer -- we think far too thin -- which also acts as the label-printing surface. This and not the data side is most vulnerable to scratching and thus signal loss!

Let's now put our freshly minted new CD into a player whose task it is to read the representation of the amplitude information of the original waveform at the sample rate of the player's internal clock - the standard 44.1KHz RedBook velocity. From this readout of the pit pattern in conjunction with the clock signal, the player reassembles a 1s and 0s signal that results in an analog squared-off waveform at this intermediate stage [see above]. Each time the waveform crosses the zero line -- every time a pit-to-flat or flat-to-pit transition is encountered -- the player writes a 1 to a buffer. All other samples are 0s. Thus from just a part of the original waveform, the player is able to recreate a very close approximation in digital form. However, the newly created horizontal part of the waveform -- the time data of the clock -- isn't a digital signal at all. The clock is a constant-flow analog signal generated by an analog source, a crystal oscillator. Now this stream of 1s and 0s must be converted to analog so we can hear the music.

Several things can and do go wrong during this whole process, from the glass master if generated from DAT tape or CD-R to the glass-mastering

machine to the translucent quality of the actual polycarbonate, the quality of the stamper to form accurate pits, to the reflective aluminum layer which may or may not be thick enough or suffer from pin holes.

In practice, it is the lack of crisp pit formation in a stamped CD that causes most of the problems. If a clock 'tick' prompts the laser to read the next sample and the wall of that pit isn't interpreted as a wall, the sample isn't misread but read just a little too late. Every transition from pit to flat and flat to pit becomes read as a digital 1. For a purely digital likeness, time delays don't pose any problems since the 1 is properly extracted. During playback, however, you will notice a peculiar harshness often associated with the medium. These offsets in time are called jitter.

If we tie up all of the above -- and there are in fact many more issues that influence CDs - we can conclude that all manner of mechanical and external issues can interfere with our musical pleasure of playing back a CD. In hindsight, you might even wonder why this intermediate medium was ever invented. If we had direct digital access to the master recording on the recording engineer's hard disc, we could skip all the format and domain conversions....

That could become a thing of the near future. For now, we do not have to wait. We simply accept that CD is somewhat overrated while admitting that several small labels are doing their utmost to deliver as good a product as possible. Labels like Mobile Fidelity, Chesky, MA Recordings, Waterlily and many others are examples. Needless to say, it's somewhat problematic that some of these very small labels release merely a couple of hundred CDs while the mega labels push out hundreds of thousand of copies per album.

However, once purchased, we can do something about the often bad stamping quality of a CD. When we first discovered the potential improvements possible by making a CD-R copy from an original, it was a surprise in two ways. One was the musical improvement: The copy wins in transient response, blackness, bass and treble while not much changes in the midrange. The second was the lack of difference in the pure digital domain. A bit-for-bit comparison does not show any differences between copy and original. This proves that the time domain is a factor - the clock is not on the CD and improperly formed pits affect it. Enter EAC Young German student Andre Wiethoff from Dortmund/Germany was fed up by all the audio grabbers available at the time. Audio grabbers are computer programs designed to 'rip' or copy music from a CD to create compressed MP3 audio files so detested by audiophiles. Andre dove deep into the RedBook specifications for CD and CD drives and came up with a design for the most perfect audio grabber. Most grabbers just transfer bit-for-bit data from CD to computer hard drive which results in a jitter-free copy since a computer's reading of audio data does not involve any clock mechanism other than the computer's own clock which simply prompts the computer CPU to perform an action which, unlike with CD audio, isn't limited to serial processing.

A computer running under Windows or Mac OS or any other shares its CPU not only with its operating system but with any other program that is running simultaneously. While program A is waiting for some data from the hard drive which the operating system is retrieving, the CPU can perform calculations for program B. Once the requested data has been fetched from the disk (which is relatively slow compared to the CPU that works at GHz speeds) and stored in memory, the CPU can stop working on program B and attend program A by using fresh data.

Thus CD data to a file on a computer's hard disc is a parallel computer task. If it were playing back music the same way, that would be terrible. Later we'll see why and how that works a little differently. Andre's studies of the workings of both the RedBook and CD player formats plus his cunning programming skills have resulted in the most accurate audio ripper extant. For music lovers like us, it is sufficient to have access to a program that can extract data from CDs in such a way as to 'overlook' all manner of distortions caused by either flaws during the CD manufacturing process or from prior use like scratches and to create perfect copies to our computer's hard drive.

For our purposes, we only use a small portion of Exact Audio Copy's extended features which include almost 90% of the old Cool Edit Pro program like wave comparison, frequency analysis etc. EAC only suffers one handicap. It can presently only run under the Windows operating system – no or Mac OS. On the other hand, the software is free. Andre only wants a nice postcard with a nice stamp in return. From us, he can even get a nice Blue Moon Award for Outstanding Software Contribution To The World.

After downloading the shareware from Andre's website, EAC installs as a zipped file. With Windows XP, you don't even require an external program like Winzip to unpack the file. However,

with what follows, we expect a little PC savviness to work things out for yourself. EAC is still in Beta form. At the time of this writing, Andre is at version 0.95 Pre Beta 5 but what's in a name? Unzipping the program installs itself in the folder C:\Program Files\Exact Audio Copy. You now merely need one little additional piece of software -- file WNASPI32.DLL -- to add to the EAC folder. You can download this .DLL files here. This file is essential to create communication between your CD drive and the Windows operating system. Once that DLL file is unzipped and stored in the correct folder, you are ready for the next step - configuring EAC for your environment.

The best results so far have been achieved with a combination of SCSI-based CD reader/writer (ideally set up on a vibration- isolated platform) and a dedicated hard disc, preferably also of the SCSI kind. Now run the EAC software. An install wizard will help you through the setup steps. The program first scans the computer for CD drives and you will select the one to use if more than one are available. Andre supplies the software with a list of known drives for optimal settings. Those can be overruled but for popular drives like a Plextor SCSI, the default settings are perfectly calibrated. Now skip all questions about external decoders – we are not interested in compressed files, we want better copies! Answer the next question about beginner or expert with expert. The finish prompt then exits setup.

For more accurate settings, go to the EAC Menu and choose the EAC Options tab. In the Extraction tab, select High Error Recovery Quality. Since we won't create MP3 files, deselect all boxes under the General tab in the Menu. The same goes for the check boxes under Tools. Now proceed to the most important settings by selecting the Drive Options tab from the EAC Menu. Click away the warning and look at the Extraction Method tab. This hides the pearl in Andre's oyster. Make sure to enable Secure Mode. This causes the program to read each track of a CD at least twice and most of the time not even at full speed! In fact, we've observed EAC scan a CD and re-read a specific track more than 20 times. In theory, EAC can read a track up to 82 times to guarantee the best possible data extraction [i.e. overcome what might invoke the error correction protocol if your CD player read that particular passage]. To prevent EAC reading from the drive's own memory cache upon repeat scans, check the box Drive caches audio data so that EAC can switch the caching off by itself. It is this cache in conjunction with the memory used by an audio player program that plays back a CD on your PC. It buffers enough music data to play from buffer memory while the operating system as prompted by the audio player software retrieves additional audio data which is stored in the cache and at a particular memory location. If your CD drive is capable of its own C2 error correction, uncheck that on the screen. For best results, all this should be left to EAC. If you are not sure of your CD drive's capabilities, EAC offers automated settings. This comes in handy when your drive is not listed in the EAC database pre-installed with the program. Now place an audio CD into your CD reader/writer drive and make sure that the CD is of good quality like a Chesky pressing. Click the Detect Read Features button in the Options window. After a few minutes, click apply (not OK!). The program will now ask you to support the EAC community by submitting the drive settings as displayed to the EAC website so that this data may be included in the growing database for future users. After this, return to the Drive Options tab and make sure that Secure Mode is still enabled. Finally go to the Drive tab and click the Auto Detect Read command. This concludes the basic setup.

More elaborate settings are in order for older drives. With the current prices for CD writers, a modern SCSI drive will not rip you off too much (pun intended). Modern drives include a feature called Accurate Stream. This means that if the TOC tells your player that is has to go to block 10000 on the disc, it really does go to 10000 and not 9998 or 10005. Without Accurate Stream, there can be discrepancies between players. For that reason, Andre Wiethoff determined the offset of his own preferred drive. From that and a list of known CDs with their relative offsets, EAC can calibrate your drive for exact offsets. Use several of the CDs published on the list to determine the best correction setting. Now you are ready to make your first Exact Audio copy. Put a CD in your drive, run EAC and observe all your CD's tracks displayed in the window. Select one or more to copy. From the EAC tab select your preferred copy -- selected or all -- and that a cue sheet is to be made. Next select the folder where you want to store the data. Remember that a dedicated, freshly initialized disc is the best to use, not one emptied by just deleting all old files and folders. Now EAC starts its noble job. It results in either a selection of tracks in .WAV form or one big .WAV file containing all tracks while a separate cue sheet is being formed. When you are done reading the CD to your hard drive, you can begin the burning session. For this you can use any CD burning software like Nero or EAC, which features a pre-installed and very decent CD burner under the Tools tab. This program is self-explanatory and uses the cue sheet as a base. Do not expect all CD copies to be better than the original. Only those originals that are mechanically challenged in one way or another are improved. Sublime CDs are just copied in all their original glory and unchanged as they are. However, in most cases, a copied CD sounds better than the original even if it is only true for certain tracks. A freshly burned CD-R has often far better articulated pits than a pressed one. Just like with vinyl pressings, the stampers wear out and the record company is not always willing or finacially able to replace them every x-number of CDs. Worse, many times CDs are re-issued using old worn stampers. Freshly cut CDs nearly always contain less jitter than mass-duplicated commercial versions. However - what CD-R blank to burn your precious ripped copy to? Audio or Data CD-R? Gold, silver, red or black? There are many more variants of CD-R blanks than of pressed CDs and there is a basic difference. To start with, a blank CD-R is not completely blank but contains a prefabricated wobble groove to guide the burning laser from the inside of the CD-R to the outside. At –35 second before the first actual audio, the writing process burns certain additional data. The music starts at 0 seconds. The pre-music data contains track information. In the finalizing process, this data is transferred to the TOC. The area at –13 seconds on the CD-R is used by the laser burner to establish the intensity setting to determine what kind of CD-R it is about to burn to. A recording is finalized only when all data in the lead-in area is completed, the TOC has been established and the final lead-out following the user data written.

Just like a pressed CD, a CD-R consists of a 1.2mm thick polycarbonate disc, albeit with an intermediate recording layer formed by organic dye. Above that, you'll find a layer of reflective silver or gold and -- again a very thin -- protective lacquer top coat. When viewed from the recording side, a CD-R can be green or blue in color depending on the type of dye used. Green indicates blue cyanine dye with a refractive layer of gold. Blue points at a reflective layer of silver. Yellow hues arise from phthalocyanine. Another common dye is azo. They all have their pros and cons mostly with regard to longevity, which is very important for archival computer storage. The pre-groove is a wobbled 22.05kHz sinus groove of 0,6 micrometer width and modulated just like an FM carrier with a 1KHz signal to create a clock signal. During writing,

the laser heats up the dye and turns it more opaque, making the spot less reflective to create the usual pit and flat pattern. For our purposes, we want a CD-R that is durable while providing the best audio quality. That does not mean that we have to use audio- branded CD-Rs, which are especially produced for dedicated audio disc writers. In most countries, audio discs impose an extra tax that should benefit the music industry. However, we can just as well use ordinary data CD-Rs. Not long ago, Kodak gold blanks were a good choice since they were made for long-lasting storage use with their edges sealed. Do not circumcise a non-gold CD. You might expose the reflective layer to oxidation. Also, Kodak's reflective gold layer did not suffer any pin holes.

Then black CD-Rs entered the market. Those are made of colored polycarbonate with a reflective layer of silver. These were at first intended for the video game market. Sony's Play Station games arrived on black CDs and were considered cool. Soon music lovers started to use black CD-Rs and next to the notably improved musicality of expertly ripped and burned CDs, it appeared that black blanks added even further performance gains though a bit-by-bit comparison does not show any differences.

There is something special about this kind of CD-R. What though? One plausible theory claims that the black polycarbonate substrate has better translucency and creates improved dye absorption for a pit that's better defined. A better-defined pit means less jitter and more music!

A disintegrated CD

Black isn't black by the way. A lot of black CDs are reddish-black, others bluish-black. We just picked up a few French carbon CD- Rs made by MPO. They claim better UV resistance so you can leave them in your car exposed to sun. When used for normal audio use, they sound great. All this makes it worthwhile to plan for an upcoming (black) CD-R shoot-out. We'll use the summer to start a collection of blank CD-Rs.

Legality Fellow moonie Jules is more at home with this subject of the law though we personally believe that it is (still) our right to make a copy of a CD we purchased for personal use. Moreover, it is also justifiable to make a copy of an out-of-print CD and give that to a friend. As long as there are no financial gains, this should be okay. Making compilations is a fascinating way to share new music with others. Make a compilation CD of your favorite music pieces and give it to a friend. It is very personal and challenging and when the recording quality is very good, it's even more rewarding.

The industry has other ideas and wants to protect 'their' music with everything they can think of - , law suits, SACD (or was there another reason?)... you name it. Of course gross commercial piracy should be stopped. But what if you cannot make a legal copy of a CD you bought for a substantial amount of money? A little googling presents you with various tools like WinDac to overcome copy protection but the quality isn't the same as with EAC.

Summary To wrap up, you merely need a few things to make great copies of your CDs. Nothing more is required for the best quality. Any system with better specifications like external FireWire DVD/CD writer, Titanium processor etc. merely speeds things up but doesn't make them better. The minimum requirements are:

● a simple PC with a SCSI card and Windows XP, even an old Pentium 1 will do ● an external SCSI CD reader/writer, vibration-isolated ● a dedicated hard disc for intermediate storage ● Exact Audio Copy licensed via postcard

● wnaspi32.dll

● high quality CD-R (gold or black) ● a little patience ● something to get that smile off your face ● and of course great music to start with.