Dimensions: 17 by 3 1/4 inches (front), 10 1/2 inches deep plus clearance for connections. Price: $1,699. Warranty: Limited, two years parts and labor if warranty card is submitted within 14 days of purchase; otherwise, 90 days. Manufacturer: Cambridge Audio Systems International, Ltd., England. U.S. Distributor: Celestion Industries, Inc., 89 Doug Brown Way, Holliston, Mass. 01746.
Hailing from across the Big Pond, England's Cambridge Audio has been known primarily for its midline amps and preamps. However, it has recently made a splash with a series of expensive, technically sophisticated Compact Disc players. While many of us are still pondering 18-bit digital-to-analog converters (DACs) and eight-times oversampling digital filters, Cambridge has (or have, to be British) announced an upcoming 32-bit machine with 16-times oversampling. In the meantime, the latter development is currently on display in the 16-bit Cambridge CD-2.
Like a number of European and American audio companies, Cambridge does not build CD players from the ground up but, rather, bases them in part on an existing chassis from Philips. Such is the case with the highly modified CD-2. According to Cambridge, here's how the "16 x 16" decoding system works: Each channel employs a Philips four-times oversampling digital filter, which feeds the original data plus three re-samples (for a total of four samples per 16-bit "word") to the custom-made Cambridge "16 Times Module."
This module is essentially another four-times oversampling filter that quadruples the data again and passes it successively to four Philips 16-bit DACs (TDA1541). The outputs of the DACs -four per channel, eight total--are summed and fed via a coupling capacitor directly to the analog outputs. As you can see, each DAC ends up processing four samples per 16-bit word, just as it would in a conventional four-times oversampling player. Because of this parallel processing, the extraordinarily high data rate (bits per second) of the entire system is brought down to match the processing speed of the individual DACs.
If you noticed something missing in this chain of events, you're right: Because of the high sampling rate, the ultrasonic "images" created at multiples of the sampling frequency begin so far out (in this case, at around 705.6 kHz) that no analog output filter is needed to remove them. It has been suggested, and Cambridge contends, that a typical analog filter can introduce audible side effects. Using 16-times oversampling simply eliminates a suspected source of problems.
Given the CD-2's sophisticated in nards, you may be taken aback by its limited array of operating features. However, those that are conspicuous by their absence-a headphone jack, a keypad for direct track selection, and A-B segment repeat -are somewhat compensated for by three less common features: an LED indicator for disc errors (those requiring interpolation, extremely rare on undamaged discs); another to indicate playback of discs made with treble pre emphasis; and an index search function.
Even though it has only 13 buttons, the front panel takes some getting used to because the buttons are all the same size.
Fortunately, the remote control is quite manageable and can be used to program and review the 20-selection memory.
Functionally, the CD-2 reminds me of the stereotypical British sports car in that it demands a certain appreciation of electronic quirkiness (you know-turn on the wipers to get headlights). A supplement to the well-written owner's manual serves up this understatement: "The CD-2 is a very advanced Compact Disc player but some of the operating modes are a little unusual." To begin with, the CD-2 cannot be turned off un less you unplug it-this explained as avoiding a warm-up time for the complex decoder system. Pressing STANDBY only switches power to the display panel.
In additional documentation supplied to me, Cambridge mentions that some audiophiles claim improved sound playing discs with the display off.
Those audiophiles may actually be protesting the (admittedly) anarchic behavior of the LED panel, which is arranged to show track and index numbers on the left and time into a track on the right. But sometimes the display gets confused and swaps the positions of the track/index and time indications, requiring that you unplug the player to restore order. More distressingly, the display limits the usefulness of the three speed (first two audible) search functions by failing to keep time with--or at least trail consistently--the movement of the laser across the disc. Sometimes the time display doesn't change at all until the search button is released. Another oddity is that the remote can initiate play from the open-drawer position, but the same control on the front panel cannot.
Out of all this comes an unusually positive feature: Hitting the play button while play is in progress recues the laser to the start of that track; as a result, the previous-track function does, in fact, skip back one full selection.
On the back of the CD-2 is a pair of conventional analog outputs as well as a digital-output pin jack and another that can, in the future, link the CD-2 with other Cambridge components for sys tem-wide remote control. Although they are clearly labeled, these four like-colored jacks are arranged as two vertical pairs, creating the potential for unpleasant misconnections.
------------ All data were obtained using the CBS CD-1, Sony
YEDS-7, Philips 410 055-2, and Philips 410 056-2 test discs
Channel Separation (at 1 kHz) 00 dB
Channel Balance (at 1 kHz) 0 1 dB S/N Ratio (re 0 dB; A-weighted) without de-emphasis 115 3/ 4 dB with de-emphasis 116 1/2 dB Harmonic Distortion (THD.N; 40 Hz to 20 kHz) at 0 dB 0.035% at -24 dB 0 042% IM Distortion (70-Hz difference; 300 Hz to 20 kHz)
Linearity (at 1 kHz) undithered dithered
Tracking & Error-Correction maximum signal-layer gap maximum surface obstruction simulated-fingerprint test pass
Maximum Output Level 2.55 volts
Output Impedance 550 ohms
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None of the CD-2's unusual operating characteristics affect its audio performance, which is more than adequate in the most important respects. For example, frequency response is ruler-flat to about 7 kHz, where rolloff commences smoothly to - 1/2 dB at 20 kHz-preferred, if you find, as I have, some CDs with rather bright top ends. Linearity is excellent all the way down to -80 dB in tests (dithered and undithered), with the result that distortion is minuscule and totally inaudible. We have tested a number of players this year with disappointing linearity figures, leading us to appreciate even more the CD-2's good performance in this area. We have also tested players (less expensive ones, too) that meet or exceed any of the CD-2's marks; but microscopic distinctions in test data among competent players vanish in the full-frequency spectrum of music. And here, I was perfectly satisfied with the CD-2's sound, display on or off.
If I could point to a definite audible--or even measurable-positive con sequence of 16-times oversampling, I would object less to the CD-2's twisted display and dear price. It's possible that our sample unit, although a production model, had a defective control micro processor, but I doubt this, given the near-admission in the manual's supplement of some quirks in this area. Cam bridge is to be commended for its earnest effort to optimize the CD-2's sound quality; taken as a package, however, the player is a mixed blessing.
-Christopher J. Esse
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Also see:
Sony CDP-507ESD Compact Disc player