CD-CHECK Test Disc "Not since the introduction of the Dennison Protractor have I found an audio set up tool as impressive and useful as the CD-CHECK. ... Congratulations to the folks at Digital Recordings for a truly spectacular product." Gary Harrington, Audio Consultant, HARRINGTON AUDIO, Canada. .. MORE customer testimonials 1

Do CD players reproduce 100% of recorded music?

Not always. Errors created by the manufacturing process, as well as dust, scratches and fingerprints, send many CD/DVD players into a tail spin, resulting in data loss and faulty sound reproduction. This manifests itself as poor stereo imaging, lack of clarity and transient response, and dynamic-range distortions. In more severe cases, it leads to audible clicks, muting, looping and skipping.

But CD/DVD players not suppose to do that! You may say. They are all "pretty good"! You may add. Well, we thought so too, until we bought our first CD player. It turned out to be anything but "good". In fact it became a source of constant frustration from the day of purchase. So, what makes one CD player better than other? Many factors. But, one important factor has to do with the players's ability to read data from the disc. CD players have built-in D/A converters that turn the digital data on a CD into an analog signal. Ideally, all the digital data should be converted to the analog format. In reality, many factors cause digital data to be lost and sound reproduction to deteriorate. CD players have a sophisticated error correction system that allows them to recover lost data. However, when the data loss is greater than a system's recovery ability, some of the signal is lost. It is then that the CD player uses concealment methods such as interpolation, data substitution or signal muting to make this loss as inaudiable as possible. However, this results in altered and often distorted sound. Good players rearely resort to concealment methods when reading data from the disc. They will try to faithfully recover every error. How to find out how well a CD player reads data? Testing for data loss is normally a complex and time-consuming procedure that requires technical background and expensive equipment to perform. Our product, the CD-CHECK compact disc, is quick and easy to use. For the first time, it allows evaluation of the CD player's "error correction headroom" (i.e. player's ability to correct data errors) and "tracking" (i.e. player's ability to stay on track despite of disc surface or other errors). Similar products were so far available only to professionals at the cost of $100 to $300 US and required additional test equipment. Unlike those products, CD-CHECK is available to general public as well as professionals and requires just ears and eyes as "instruments". It is less expensive, quick and easy to use, and more effective in evaluation of tracking and data loss. Many people consider CD-CHECK the best product on the market. How does CD-CHECK work? CD-CHECK uses special digital signals in combination with disc error patterns arranged over five tracks. The five tracks contain a sequence of progressively difficult tests refered to as Check Level-1 to Check Level-5. The higher the Check Level passed the more reliable the sound reproduction of the CD player. A smooth, continuous tone indicates the player passes that Check Level. Any clicks, interruptions, skipping or looping indicates failure of a Check Level. 1 CD-CHECK Error Sizes Check Level-1 standard manufacturing errors Check Level-2 0.375 mm Check Level-3 0.750 mm Check Level-4 1.125 mm Check Level-5 1.500 mm How does CD-CHECK rate CD player's ability to read data? If a player passes: Check Level-1 At minimum each player should pass this level. If it doesn't it should be serviced. Check Level-2 Average Check Level-3 Good Check Level-4 Very Good Check Level-5 Excellent. This player is most capable of perfectly correcting errors caused by manufacturing faults, scratches, etc., without sound alteration or distortion. According to CD-CHECK tests, a good CD/DVD player (i.e. passing at least Check Level-3) is able to fully compensate for manufacturing errors, dust, fingerprints, and scratches on the CD/DVD surface. compensate for errors generated by its own laser pickup and mechanical tracking and guidance system, compensate for errors generated by its own laser pickup and mechanical deterioration over time and still deliver high-quality, unaltered sound over long period of time, compensate for damaged and ageing CDs or those with manufacturing errors, as well as deliver perfect music and test signals without skipping and alteration. What are the specific uses of CD-CHECK? Use CD-CHECK when buying a new or used CD/DVD player. It is not uncommon to buy a CD player that does not pass Check Level-2. If you are the unlucky owner of such a player sooner or later you will be experiencing problems as those described in "The CD Story". Save yourself money and frustration by testing the player before you buy it, right in the store! With CD-CHECK you can do the test in just 20 seconds. to evaluate existing CD, DVD and CD-ROM players for data loss. CD players detorierate over time. Protect your audio investment by detecting pickup defects early. Use it to determine when pickup adjustments are needed. Use it to check the adjustment effectiveness. Test your player especially prior to warranty expiration. If you are a service shop technician use CD-CHECK to help you with the rapair process. to determine if the laser lens needs cleaning. With CD-CHECK at your disposal you don't have to clean the laser lens every 8 hours as often recommended by manufacturers of the cleaning products. Use CD-CHECK to determine when cleaning is needed (your player passes Check Level lower than that during the last test) and save the lens from unnecessary abrasions. to evaluate the safety and effectiveness of sound-enhancing technologies. With CD-CHECK you can, for the first time, objectively evaluate various gadgets and gizmos. At Digital Recordings we tested several "audiophile" technologies with it, such as "magic" markers, stabilizing rings, "magic" discs, etc., with very interesting results. For more on each of these points click here. What do our customers say about CD-CHECK? We have received many enthusiastic testimonials regarding CD-CHECK. To read a sample of them click here. Empower yourself with CD-CHECK ! Do not expect manufacturers, sales people and audio magazines to represent YOUR interests ! If you are looking for a player that offers 100% of music and not just an approximation you need CD-CHECK to test the player yourself. For more click here.

Interested in buying CD-CHECK? CD-CHECK is offered for $49.95 CAD plus shipping and handling. Payment Methods Money order, wire transfer Transaction Currency Canadian Dollars ($CAD) Order Processing Within 5 business days from the day payment is received Shipment World-wide; via Canada Post air mail To place an order using wire transfer or money order fill out this The price of $49.95 CAD applies to non-commercial use only. If you are interested in obtaining a commercial licence please contact Digital Recordings directly.

We are looking for CD-CHECK distributors. Please contact us directly for details.

Suggested Reading: More about CD players and CD-CheckTM Why Data Verification is not enough! Consequences of Nyquist Theorem for Acoustic Signals Stored in Digital Format How to Evaluate CD Players -- and How NOT to Enhance Their Performance

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