Soundcraftsmen Pro-CD750 CD-player Review

Soundcraftsmen’s Pro Series audio components are intended for use in high-quality home systems, but their construction standards are closer to those of professional equipment than of typical consumer products. In styling and finish, the Pro-CD750 compact disc player resembles its companion preamplifier, the Pro-Control Four, which we reviewed in July, and it has several operating and control features not usually found in CD players.

Most of the controls on the Pro-CD750’s satin-gray panel are soft-touch pushbuttons; two small knobs control headphone volume and “Spectral Gradient.” The latter feature is actually a specialized treble control designed to compensate for some of the qualities of CD sound that have aroused objections among some listeners. Specifically, some CD’s, especially early releases, occasionally have harsh, unpleasant high-frequency characteristics. Although such qualities probably result from less-than-optimum recording techniques, they have often been cited as weaknesses of the digital recording/playback system itself.

Most conventional tone controls are unable to correct the so-called “CD sound.” The Spectral Gradient control provides just that function, leaving the amplifier’s tone controls to deal with more general frequency-balance problems. With its knob at the clockwise limit, the control is effectively out of the circuit. Counterclockwise rotation modifies the high frequencies in a subtle manner, removing the harsh “edge” from the sound without audibly affecting the overall quality of the program.

The second unusual control of the CD750 is a button marked differential compander. The compander is designed to fit the extended dynamic range of the CD medium into the limits of “real-world” home listening conditions. It is also extremely useful when taping a CD for playback in a car audio system, where the high noise “floor” of the mobile environment makes it impossible to appreciate the full dynamic range of most CD’s. The Differential Compander reduces the level of loud program passages and raises the level of soft passages, leaving the average level nearly unchanged.

The basic controls of the CD750 are quite conventional, including play/pause, forward and reverse track skipping, fast search with audible sound, and repeat and programming controls. The machine can be programmed to play back up to fifteen selections in any order, and the repeat button can be used to repeat the programmed sequence, the entire disc, or any selected portion of it.

The small display window provides only the most basic information. Normally it shows the current track and index numbers, and the time button switches it to a display of the elapsed time in the current track. While the search functions are in use, the display automatically switches to its time mode. When the pickup is between tracks, a blinking triangle appears in the display.

The player is supplied with a compact wireless remote control that duplicates most of its front-panel functions as well as providing direct access to any track through its numbered keys (not present on the front panel).

The Soundcraftsmen Pro-CD750 uses double oversampling at a frequency of 88.2 kHz and 16-bit linear quantization. Its ratings include a dynamic range of 95 dB, a signal-to-noise ratio (S/n) of 99 dB, and a frequency response of 5 to 20,000 Hz ± 1 dB. The channel separation, at an unspecified frequency, is rated as 86 dB. The player measures 19 inches wide, 11-3/4 inches deep, and 3-5/8 inches high, and it weighs 12 pounds. Price: $599.

Lab Tests

Although the open-circuit output voltage of the Soundcraftsmen Pro-CD750 was exactly 2 volts, it decreased to 1.69 volts when the player was terminated with the EIA standard load of 10,000 ohms in parallel with 1,000 picofarads. The outputs of the two channels were identical. The frequency response was well within the ratings, varying only +1.5, —0.3 dB from 20 to 20.000 Hz. The 1,000-Hz distortion was somewhat higher than rated, ranging between 0.045 and 0.09 percent at outputs from 0 to —20 dB; it consisted almost entirely of second and third harmonics.

The measured S/N of 107 dB handily surpassed the rating, as did the dynamic range of 96.8 dB. Channel separation was not as great as that of most home CD players, varying from 84 dB at 100 Hz to 48 dB at 20.000 Hz. The interchannel phase shift at 20,000 Hz was 40 degrees, indicating the use of a single double-oversampling digital-to-analog (d/a) converter for both channels. The low-level linearity of the d/a converter was better than average, with a maximum error of 2.7 dB at a — 90-dB level.

The player’s cueing accuracy was excellent, and it was not affected by any of the calibrated defects on the Philips TS5A test disc. A strong slap on the top of the cabinet was needed to induce momentary mistracking. Its slewing time and general track-to-track access times were considerably slower than we have seen in many current CD players, however; several seconds elapsed between selecting a track and hearing the first sounds from it.

We were especially interested in the effects of the Spectral Gradient and Differential Compander features. The former had a very subtle action over most of its control range, although a moderate reduction in highs was plainly audible when the knob was fully counterclockwise. Our test measurements showed a slightly sway-backed high-frequency response dip, about 0.7 dB with the control almost fully clockwise, that deepened gradually to a maximum depth of only 2.5 dB at 7,000 to 8,000 Hz when the control was nearly at its counterclockwise limit. At the limit, however— which, strangely, was marked “+” on the panel—the entire shape of the response curve changed, dropping off steeply about 2,000 Hz. But since the response was down only 3 dB at 8,000 Hz, the audible effect was very mild even at the control’s limit.

The Differential Compander effectively tilted the input/output transfer function of the player around its — 24-dB point. In normal operation, playing test tones whose level decreased from 0 to —90 dB produced output signals with corresponding levels. With the compander on, a 0-dB signal was reproduced at —10 dB, and the output from a — 90-dB tone was boosted to —70 dB, leaving the levels between —20 and — 30 dB almost unaffected. Thus, a 90-dB dynamic range on the disc was effectively reduced to a 60-dB range, which is fully compatible with any home or car components and probably easier to live with in most home environments. There were no deleterious effects on the sound. Finally, we found the headphone volume to be very good, suff icient for serious listening even with moderately high-impedance phones.

Comments

The sound quality of the Soundcraftsmen Pro-CD750, with or without using its special features, was excellent. The Spectral Gradient control was surprisingly effective in taming some of the harsher CD’s we tried; it took the unpleasant high-frequency hardness away with no detectable loss of music content or subjective balance. Best of all, perhaps, the feature cannot be misused—there is no way it can make a recording sound dull or otherwise unlistenable.

The Differential Compander also worked well. Its name accurately describes its function: It compresses the high-level signals and expands the low-level signals, retaining a linear overall input/output characteristic while substantially reducing the dynamic range.

For the most part the CD750 was very easy to use, and certainly enjoyable to hear, but I found some of its human-engineering features less impressive. Surely there is a happy middle ground between its minimal display and the garish, “tell them more than they want to know” displays of some other players. I would prefer to see both the track number and the playing time without having to push a button to select only one of them. I would also prefer a faster response to track-selection commands. Incidentally, track selection with the remote control has its own peculiarity. After the player has cued the right point, it switches into pause without any indication except the absence of the triangular play/ pause symbol on the display. In fairness, I must say that the manual does state that direct track and index selections can be made only in the stop mode.

Nevertheless, the CD750 is a fine CD player, and my criticisms should be assessed in the context of its overall performance. In practical terms, the useful and well-executed Differential Compander and Spectral Gradient features more than compensate for the player’s minor quirks.

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