Manufacturer's Specifications:
Frequency Response: 20 Hz to 20 kHz, ± 0.25 dB.
S/N Ratio: Greater than 100 dBA re: 0 dB.
THD: Less than 0.01%, 20 Hz to 20 kHz, at 0 dB; less than 0.1%, 20 Hz to 20 kHz, at- 20 dB.
Channel Separation: Greater than 86 dB, 20 Hz to 20 kHz.
Phase Shift: Less than 5°, 20 Hz to 20 kHz, between or within channels.
Output Level: Fixed, 2.0 V rms at 0 dB, ±0.5 dB; variable, 0 to 2.0 V rms; headphone, 0 to 3.0 V rms into 30 ohms.
Dimensions: 17.5 in. (44.5 cm) W x 2.8 in. (7 cm) H x 14.8 in. (37.7 cm) D.
Weight: 17 1/2 lbs. (7.9 kg).
Price: $895; optional RC1 remote-control unit, $99.
Company Address: One Progress Way, Wilmington, Mass. 01887.
ADS obviously intends this, their first Compact Disc player, to be part of their highly regarded Atelier series of audio components. Not only is the styling of the CD3 consistent with that of the other components in that series, but its performance and features clearly identify it as a top-of-the-line product. As was pointed out to me by Richard Moore of ADS, the CD3 is the company's second fully digital product.
Some of you may remember the ADS10 Acoustic Dimension Synthesizer, a digital time-delay unit which used A/D and D/A adaptive delta-modulation conversion techniques developed by Delta Lab. The CD3 is an international product, in the best sense of the phrase, with the developmental engineering work done on a cooperative basis by engineers from ADS and its sister firm, Braun Electronic GmbH, of West Germany, while a highly regarded Japanese company does the actual assembly work in that country.
The CD3 can handle and play discs with up to 99 tracks, and as many as 30 selections can be programmed in random sequence. Using the optional remote control, any 30 of the 99 tracks can be programmed, with any selection accessible immediately; using the front panel controls, only the first 30 tracks are programmable.
The controls have been grouped in a most logical fashion, with the more often-used basic controls placed together on the front panel in full view. The more specialized and less often-used controls are on a push-to-release, pivoting panel below the disc drawer. These controls allow the more sophisticated user to perform such functions as toggling be tween display of elapsed and remaining time, toggling be tween track and index numbers, programming selections, and choosing any portion of the disc for repeat play.
I have often been asked what differentiates a really superior CD player from an "adequate" one. The ADS CD3 may help to answer the question, for it is definitely in the superior class, as evidenced by some of its mechanical innovations as well as by its electronic and sonic performance. The smoothly operating, motor-driven loading drawer, for example, cradles the CD on soft cushions to prevent any damage to the disc itself. The slider responds quickly, smoothly, and noiselessly. Like other ADS Atelier components, the CD3 uses steel top and bottom covers for mechanical strength and shielding. The spindle motor is an extremely quiet, d.c. brushless type.
I found the laser tracking-servo system to be quite resistant to external shock and vibration applied to the sides of the unit. The sample I tested showed some sensitivity to mechanical shock applied vertically, but I am told by ADS that a cure is being worked out by shock-mounting the transport. In any case, vertical shock is the least likely type of mechanical vibration to occur in actual use.
Circuit Highlights
The CD3 employs two-times oversampling (88.2 kHz) with digital filtering. Separate digital-to-analog converters are used in each channel, with full 16-bit linear conversion.
Hypersonic, multiple-pole, analog filters with cutoffs above 35 kHz are used for improved spurious-response rejection.
These filters exhibit extremely flat frequency and phase response in the audio band and, according to ADS, have less than 5° of phase shift at 20 kHz. I found that the extremely quiet and low-distortion analog stages placed no dynamic-range limitations on this player.
The CD3 employs advanced digital circuitry for tracking and control functions and for signal processing. This VLSI circuitry is under the control of two internal, eight-bit micro computers which operate together for rapid control of tracking and error-correction circuits, and for rapid response to front-panel or remote-control command inputs.
Control Layout
The controls on the CD3 are, above all, designed to perform complex functions while remaining extremely simple to use. For example, pushing the power button, with a disc in place, will place the mechanism in the pause mode and give a readout of the total number of tracks on the disc and the total playing time. Loading of the disc drawer can be done by pressing the "Start" button or touching the "Slider" button. A "Pause" button functions as its name suggests, while the "Skip" button moves the pickup to the beginning of the next track if play is in progress. If "Skip" is depressed for longer than 0.5 S, the track or index number increases by one every half-second. Releasing the button advances the pickup to the track or index number shown at the time of release. Fast-forward and fast-reverse operate at three times normal speed when these buttons are first pressed, and at 20 times normal speed if the buttons are held down for more than 5 S. The return button sends the pickup back to its rest position and switches the disc-drive motor off.
The display area above the slider drawer incorporates a four-digit, seven-segment display for indicating elapsed or remaining time, and a two-digit, seven-segment display for showing the selected track or index number.
The only other features visible on the front panel are a headphone jack and pop-out headphone level control, both at the far right, and an indication of where to push on the swing-down slider drawer to expose the programming and display controls. These handle elapsed- or remaining-time display, track or index selection and display, memory clear, and A-B play (automatic repeat between any user-selected start and end point). The CD3's rear panel has fixed and variable output jacks, with a level control for the latter.
The optional RC1 wireless remote control is designed to operate all ADS Atelier remote-controllable components, not just the CD3. It operates like a flip-up telephone/address selector, with seven overlays which show key designations for each of the components it can control. I did not have the remote-control unit on hand when I tested the CD3, but am told that the CD player will be the first ADS component controlled by this hand-held remote unit, with other components to follow.
Measurements
Fig. 1--Frequency response, left (top) and right channels.
Fig. 2--THD vs. frequency at three signal levels.
Fig. 3--S/N analysis, both unweighted (A) and A-weighted (B).
Fig. 4--Separation vs. frequency.
Frequency response, measured for both the left and right channels, was flat to within 0.2 dB from 20 Hz to 20 kHz (see Fig. 1). Output was extremely linear at all recorded levels, deviating from perfect linearity by no more than 0.2 dB over the range from maximum recorded level (0-dB reference level) to -80 dB.
Harmonic distortion at 0-dB recorded level was about as low as I have measured for any CD player: 0.003% at mid-frequencies and no more than 0.18% at 19 and 20 kHz, where many earlier generation CD players exhibited much higher distortion. SMPTE-IM distortion measurements were also extremely low, with readings no higher than 0.002% at maximum recorded levels. Twin-tone IM measurements resulted in readings of 0.0025% at 0-dB level and 0.008% at -10 dB. Figure 2 shows harmonic distortion as a function of frequency for test signals at three recorded levels. As with all digital audio systems, harmonic distortion increased linearly as signal level decreased, reaching about 0.075% at-30 dB. As for undesired "beats" within or without the audio spectrum, they were practically nonexistent in this unit-a direct result of the oversampling, digital filtering and full 16-bit linear D/A conversion techniques used in the CD3.
Signal-to-noise ratios for the CD3 were outstandingly high, measuring more than 98 dB, unweighted, and be tween 102 and 104 dB, A-weighted. The spectral distribution of residual noise is shown in the S/N analysis graphs of Figs. 3A and 3B.
At low and mid-frequencies, separation (Fig. 4) ranged from just over 83 to 84 dB. At higher frequencies, separation decreased slightly-more so in R to L than L to R. At 20 kHz, separation in both channels was still 74 dB, far more than is required for a very satisfactory stereo presentation. Output from the fixed-level jacks measured 2.04 V, while maximum level from the variable outputs was 3.24 V.
Figure 5 shows the CD3's reproduction of a 1-kHz, square-wave signal. The shape of the square wave confirms the fact that this player employs the now-preferred digital-filter approach. The very low level of ripple observed on the top and bottom of the waveform is not so much the result of phase shift (virtually none in this unit) as it is the absence of higher order odd harmonics (above 20 kHz) which are not present in the reproduced square wave. The digitally generated unit-pulse signal on my Philips test disc was reproduced with the waveshape shown in Fig. 6; again, a result that is typical of CD players which employ this advanced type of digital filtering and oversampling.
While I lack the means to check out ADS's claim of minimal phase shift between channels or within a channel, the 'scope photo of Fig. 7 does show that there was no measurable phase shift between a 200-Hz signal recorded on the left channel and a 2-kHz signal output from the right.
The simultaneous zero-axis crossing in the positive direction of both signals confirms this.
More than two years ago, when I subjected the earliest CD players to my special "defects" test disc (a disc with an increasingly wide opaque wedge, a series of black dots meant to simulate dust particles, and a simulated fingerprint smudge), it was a rare event when a player's optical tracking system and error-correction system could play through these imperfections without mistracking or muting. Now, more and more current-generation players, including the ADS CD3, zip right through this problem disc without missing a beat. The maximum width of the opaque wedge on the test disc is 900 microns. ADS tells me that their CD3 could easily handle a width as great as 1.5 mm (1,500 microns). It looks as though I am going to have to come up with a more severe tracking test for CD players! Lateral vibration and shock of more than mild severity also resulted in no mis tracking, but, as mentioned earlier, downward (vertical) external shock on the top surface of the unit did result in momentary muting and, in extreme cases, mistracking.
Fig. 5-Square-wave reproduction, 1 kHz.
Fig. 6-Single-pulse test.
Fig. 7-Phase-error check using tones of 200 Hz and 2 kHz.
Use and Listening Tests
The ADS CD3 ranks among the best-sounding CD players I have tested thus far; it reproduces well-engineered CDs with smoothness and clarity. I was particularly impressed with its sound quality during very soft musical passages, where earlier CD players have sometimes been less than outstanding.
Ergonomically, the ADS CD3 is a gem. At the time I tested the unit, the owner's manual was not yet available, yet I had no trouble figuring out what the controls did and how they were to be used. If you do most of your listening to CDs from start to finish, or want to select tracks of a disc as you listen (skipping those you don't want to hear all the way through), you may not even have to refer to the owner's manual. The display area includes a transparent window which, with its rear illumination and mirror optics, allows you to watch a CD spin while it plays. I find this not only desirable but comforting, since it assures me that all is well inside the drawer and that my favorite CDs have not been swallowed up.
If there is one aspect of the ADS CD3 that bothered me just a little, it was the fact that the remote control is not included as part of the standard package. I understand that this particular remote is intended to be used with several ADS Atelier components, and therefore it is probably a costlier item to produce. Still, adding an extra $100 to what is already a fairly expensive CD player may discourage some people from considering this particular CD player. On the other hand, given an opportunity to audition this player and operate its elegant controls, others may well feel that price is of secondary importance when such a magnificently crafted instrument is involved.
-Leonard Feldman
[AUDIO magazine/June 1985]
Also see:
ADS C2 Cassette Deck (July 1983)
[adapted from Audio magazine]