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In addition, mishandling increases a disc's data errors. A CD's top (label) side is more vulnerable than the bottom, because the pits are impressed on the label side. Scratches or contamination on the bottom surface are out of focus to the laser, and are less likely to cause errors. But scratches on the top surface can wipe out large areas of pits. The photograph in fig.7 is a CD surface on which I made a mild abrasion with a ball-point pen—mild by unmagnified visual standards. On the CD's pit scale, however, this "mild" scratch produced catastrophic damage to the spiral track.
A parameter called a "dropout" is defined as an instance in which the signal coming off the disc drops below 30% of its nominal value. Large errors combined with a dropout indicate physical damage to the disc. Large errors without a dropout could be caused by localized areas of poor pit geometry.
Although these errors are completely corrected, a disc with high error rates will have less tolerance for scratches, dirt, fingerprints, and poor-quality CD players before producing an uncorrectable error. This is especially important in CD-ROM, where bit-for-bit accuracy is essential.
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Sidebar: Clover Systems QA-101 CD Analyzer
Looking at error rates on CDs was once the domain of specialized test instruments costing tens of thousands of dollars. These CD analyzers were highly sophisticated, and often provided all kinds of statistical and graphic plotting functions useful when characterizing the quality of large quantities of CDs. The high cost and complexity of CD analyzers excluded all but CD replicators from knowing how well—or how poorly—CDs were made.
All that has changed with a new CD analyzer made by Clover Systems of Laguna Beach, California. The Clover…
MAHLER: Symphony 6
Manhattan School of Music Symphony Orchestra, Glen Cortese (cond.)
Titanic 257 (CD). 2000. Charles G. Thomas, exec. prod., Jerry Bruck, eng., Michael Karas and Eric Wagner, assoc. engs. AAD? TT: 76:27
Performance: ****?
Sonics: *****
Manhattan School of Music Symphony Orchestra, Glen Cortese (cond.)
Titanic 257 (CD). 2000. Charles G. Thomas, exec. prod., Jerry Bruck, eng., Michael Karas and Eric Wagner, assoc. engs. AAD? TT: 76:27
Performance: ****?
Sonics: *****
With such glamorous competition on the Mahler market, what could a student orchestra from the Manhattan School of Music and a virtually, unknown conductor have to offer the international recording world? Plenty, as it turns out. Critics begged for a Mahler moratorium in the early 1990s when everybody but Christopher Hogwood…
The first epiphany I experienced in blind audio testing took place in the Dunfey San Mateo Hotel, in Northern California. We were stuffed into a largish, well-lit room in which dozens of listeners sat in chairs, and others stood around the back or sat on the floor. Up front were two large B&W Matrix 801 speakers on tall stands spaced far apart, behind them, opaque curtains hid a small pile of audio equipment. John Atkinson and Will Hammond stood at stage left.
The occasion was the 1989 High End Hi-Fi Show (many audiophiles still call it the "Stereophile Show," even though it has…
Letters in response appeared in October 2005 (Vol.28 No.10):
Curious
Editor: There was a curious juxtaposition of editorial content and advertising in the August 2005 Stereophile. Page 3 has Jon Iverson discussing the problems of double-blind testing, and concluding that such testing can identify only who has the best ears. Yet then, on p.7, Revel, a respected high-end speaker manufacturer, talks about how their new and most affordable line of speakers were "subjected to the ultimate test—double-blind listening." Are we to believe Mr. Iverson or Revel? Does the editorial half of…
Combine an electrostatic panel to reproduce music's midrange and treble with a moving-coil woofer for the bass foundation. For decades, this has seemed the ideal way of designing a loudspeaker: Each type of drive-unit is used in the frequency region for which its performance is optimized. The resulting hybrid should sing like an angel.
Yet such hybrids often turn out to be mules, in my experience, their sounds remaining resolutely earthbound. To integrate drivers with very diverse radiation patterns—the omnidirectional woofer and the bipolar panel—sets the speaker engineer a pretty…
Like all electrostatic speakers, the Aerius needs to be energized from a wall AC outlet. An AC lead plugs into an IEC receptacle on the speaker's rear, all the power-supply circuitry being internal so that the speaker can be manufactured to be country-specific in terms of line frequency and voltage. Given that makers of laptop computers use universal power supplies that will work anywhere in the world without adaptors, this would seem to be a backward step. However, MartinLogan does this, I believe, to cope with the increasing amount of "gray-market" sales afflicting the international High…
I suspected from my experience with pink noise that this reticent top octave is also exacerbated by some peakiness lower in frequency, in the mid-treble. Though it was not generally sibilant, the Aerius did indeed add some slight emphasis to tape and microphone hiss. Close-miked soprano voice also took on a hard edge as it got higher in level. And the trumpets in my Elgar Dream of Gerontius recording on the second Stereophile Test CD had a little too much brassy blattiness. Changing from the YBA to the Mark Levinson No.20.6 monoblocks softened the mid-treble. This change also added an octave…
Which brings me to the Aeriuses' soundstaging. Recorded ambience, indeed, seemed more obvious, with longer decays, than I had expected from listening to the same tracks on conventional speakers. The differences between the various artificial reverberation programs Corey Greenberg had used on his "Eden" track on Test CD 2 seemed larger than I had thought. And instruments didn't move forward or backward in the stage as they were played louder or softer.
Soundstaging was generally well-focused, with no tendency for images to pull to the center. But I didn't get much of a sense of the stage…