Manufacturer's Specifications:
Frequency Response: 5 Hz to 20 kHz, ±0.5 dB.
THD: 0.005%.
Dynamic Range: Greater than 95 dB.
S/N: Greater than 95 dB, A-weighted.
Number of Programmable Selections: 24.
Separation: Greater than 90 dB at 1 kHz.
Output Level: Line, 2.0 V rms; headphone, 40 mW into 8 ohms.
Phase Response: 80° from 20 Hz to 20 kHz.
Power Requirements: 120 V a.c., 60 Hz, 16 watts.
Dimensions: 18 1/8 in. W x 3 9/16 in. H x 12 1/8 in. D (46 cm x 9 cm x 30.8 cm).
Weight: 12 lbs., 9 oz. (5.7 kg).
Price: $800.
Company Address: 100 Randolph Rd., Somerset, N.J. 08873, USA.
Kyocera's latest entry in the CD player category is a far cry from their earlier models. The DA-710CX has every imaginable convenience feature, and its circuit innovations and mechanical construction place it at the very highest pinnacle of performance and sound quality. Since the name Kyocera is an acronym based on the words Kyoto Ceramics, it is no surprise that the DA-710CX utilizes ceramic materials: Four ceramic spacers are strategically located in the chassis to isolate key components from external vibration, and zirconia-ceramic guide shafts assure smoother travel of the laser pickup transport mechanism for greater tracking stability.
Kyocera's literature notes that while other manufacturers are just now coming around to the use of true 16-bit D/A converters plus four-times oversampling, the DA-710CX actually represents the third generation of Kyocera players to use this digital-to-analog conversion technique. But the DA 710CX goes far beyond that in its circuit innovations. Of course, it employs separate D/A converters for each channel, but it also uses optical coupling to isolate the digital stages from the analog section, in order to prevent digital noise from leaking into the analog output. Other technical features of the DA-710CX include a direct digital subcode output port, third-order Bessel-derived analog filters, a three-beam laser tracking system, and gold-plated output contacts.
As for convenience features, the DA-710CX offers a complete assortment, including 24-track programming and an illuminated 20-key panel for direct access to tracks. The usual forward and backward "skip" functions are provided, as are repeat of a track, a set of programmed tracks, or a whole disc. Fast forward and reverse are also provided.
There's even a button for playing all the tracks of a disc in random order. Sony was first to offer this feature in some of their players; they dubbed it "Shuffle Play." Kyocera calls it "BGM," and though I read the owner's manual carefully, I could not for the life of me discover what the abbreviation stands for. So I called Kyocera, and learned that BGM stands for "Back Ground Music." Of course, of course! While programming is possible only for tracks, you can, in the normal access and play mode, begin playback from an index point if you wish (providing, of course, that the disc in question has encoded index flags).
A fluorescent display presents a wide variety of status indications as well as current track number and elapsed or remaining time. Additional features include a headphone output jack with its own volume control, and play activation via an external timer. The 39-function remote control sup plied with the unit duplicates all of the front-panel functions except for power turn-on. The DA-710CX can also be operated using Kyocera's RC-101/RT-102 System Remote Control, a network that integrates any compatible Kyocera receiver, cassette deck, and CD player into a single wireless remote-control system.
Control Layout
The "Power" on/off button and a "Timer" switch are at the left end of the front panel, beneath the disc drawer. To the right of the drawer, at panel center, is the large display area.
In addition to track and time information, it offers alphabetic displays such as "Set Disc," "Play," and "DIR" (direct track call-out), among others. There's also a "Play/ Pause" indicator and small lights to tell you which type of repeat-play mode has been engaged ("One" track, "All" tracks, or the musical phrase between predetermined points "A-B"). The "Open/Close" button and the basic operating controls are to the right of the display, as are such secondary control buttons as "Repeat," "A-B," "Time Remain," "Index," and "BGM." Further to the right are the 20 numbered buttons used for direct track or index access and for programming.
Additional buttons needed for programming are located below the 20 numbered buttons. A stereo headphone jack and its output level control are at the extreme right.
On the rear panel are the usual pair of output jacks, the digital (subcode) output port, and a "Remote Input" to which Kyocera's optional remote control center, mentioned earlier, can be connected.
Measurements
Figure 1 shows the frequency response at the output of each channel when playing back a swept-frequency test signal from below 20 Hz to above 20 kHz. At 20 kHz, I measured an attenuation from reference level of 0.7 dB for each channel. There was no evidence of any "peaking" or "wobbling" of the response at the high end, indicating a near-perfect post-D/A analog filter design. Harmonic distortion as a function of frequency is plotted in Fig. 2. At 0-dB (maximum) recorded level, THD at 1 kHz was only 0.004%; even more important, without interposing a low-pass filter of any kind, I found only a very slight rise in apparent distortion when THD at high frequencies was measured. In other words, the usual "beats" outside the audio band when playing a 20-kHz test signal were hardly noticeable on my spectrum analyzer (Fig. 3).
Unweighted signal-to-noise ratio (Fig. 4A) measured 98.1 dB. When an A-weighting network was added in the measurement path (Fig. 4B), S/N increased to 104 dB, about the highest A-weighted figure I have obtained from any CD player. Dynamic range, specified as "greater than 95 dB," was in fact very much greater than that conservative figure.
Measuring in accordance with the EIAJ Standard (and the future EIA Standard), I obtained a reading of 110 dB. This result was arrived at by adding the measured THD for a -60 dB signal (expressed in dB rather than percent) to 60 dB. In the case of the DA-710CX, THD for a -60 dB, 1-kHz test signal measured 0.316%, corresponding to 50 dB below the test-signal level. So, 60 dB added to 50 dB yields an effective dynamic range of 110 dB.
Linearity of the DA-710CX was accurate to within 0.1 dB all the way from maximum recorded level to -80 dB. Wow and flutter was too low to be measured, and the level difference between channels was 0.05 V (approximately 0.2 dB) for a nominal output of 2.14 V rms at maximum recorded level. SMPTE IM measured 0.012% at maximum recorded level; twin-tone CCIF IM measured only 0.0047% at maxi mum recorded level and 0.003% at -10 dB.
Stereo separation, including the effects of my connecting cables and measurement instrumentation, is plotted in the graph of Fig. 5. At mid-frequencies, I measured left-to-right and right-to-left channel separation of approximately 81 dB. The symmetry of the 1-kHz square wave shown in Fig. 6 and of the unit pulse in Fig. 7 confirms Kyocera's use of digital filtering and oversampling. There was a slight phase error between the left- and right-channel outputs of a 20-kHz test signal, as shown in Fig. 8. If there were a complete absence of phase error or time delay between left- and right-channel outputs, the Lissajous pattern of Fig. 8 would be a straight, 45° line. One can see a slightly elliptical pattern here; however, this does not imply the use of a single D/A converter. Had only one D/A converter been used, a much more pronounced ellipse would have been displayed. The slight phase shift evident in Fig. 8 is more than likely the result of a small phase error caused by components, such as coupling capacitors, in the player's analog output stages. It is so minimal as to be of no concern to me.
Fig. 1--Frequency response, left (top) and right channels.
Fig. 2--THD vs. frequency at 0-dB (maximum) recorded level. Dashed line
shows effect of out-of-band "beats" rather than true distortion.
Fig. 3--Spectrum analysis of 20-kHz test signal. Sweep is linear from 0 Hz
to 50 kHz.
Fig. 4--S N analysis, both unweighted (A) and A-weighted (B).
Fig. 5--Separation vs. frequency, from left to right and from right to
left channels.
Fig. 6--Reproduction of a 1-kHz square wave.
Fig. 7--Single-pulse test.
Fig. 8--Interchannel phase comparison at 20 Hz. Slightly elliptical
pattern indicates minimal phase error. (See text.)
Use and Listening Tests
I find that the easiest CD players to use are those which allow you to "punch in," by number, the tracks that you want to hear. The DA-710CX, with its 20 numbered keys, falls into that category. Kyocera has even come up with an easy method for calling up tracks that have numbers higher than 20: First, one pushes a button labeled ">10"; then two additional number buttons are pressed, each corresponding to a digit of the track number desired. Speed of access was very good-something less than 1-sec between adjacent tracks and no more than 4 S from an innermost to an outermost track. Tracking stability was superb, and the player had no difficulty handling the simulated scratches, dirt, and fingerprint smudge on my "defects" test disc.
With all of the circuit refinements and user convenience features found in the DA-710CX (not to mention the excel lent lab measurements), I would have been mighty surprised if this latest player from Kyocera had not sounded great. Sound reproduction, in fact, was so clean and open that I couldn't resist playing some of the early "problem" discs--those which lacked good stereo depth and those whose tonal balance seemed harsh when played on a first-generation CD player (I keep such a player on hand, just to refresh my memory). Played on the Kyocera, a few of those early discs still left something to be desired. More than half of them, however, seemed to benefit from the modern de sign philosophy embodied in the DA-710CX.
If you want to hear what a good CD player can sound like when playing well-recorded discs, put on a copy of Telarc's Round-Up, featuring the Cincinnati Pops Orchestra playing a wide variety of music associated with the American West.
The folks at Telarc have included a rousing version of the last part of Rossini's "William Tell Overture," the section that's irrevocably associated with The Lone Ranger. I tell you, played on the Kyocera hooked to a good component system, the clean, unmuddied bass and the wide dynamics of this rendition were enough to turn Silver into a bucking bronco! The BGM (random play) feature proved fun to use with this disc, as well as with others I own that contain a wide variety of unrelated selections. However, I still think the wrong acronym has been chosen for this feature. With the kind of sound that the Kyocera DA-710CX produces, a more apt acronym might have been "FGM," for Fore Ground Music!
-Leonard Feldman
(adapted from Audio magazine, Sept. 1987)
Also see:
Kyocera DA-01 Compact Disc Player (Aug. 1983)
Kyocera R-851 Tuner-Amp (May 1983)
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