Description: Optimus CD-3400 single-bit portable CD player with four preset equalizer positions: flat, bass boost, treble boost, and bass boost + treble boost. Frequency response: 17Hz-20kHz, ±1dB. Dynamic range: 90dB. S/N ratio: 94dB. Separation: 77dB. Maximum line output level: 720mV. Power requirements: 6V, whether from four AA batteries or optional RadioShack #273-1655 AC adapter. Operating time (alkaline batteries): approximately 7.5 hours. Supplied accessories: line-out interconnect, carrying case.
Dimensions: 1½" (27mm) H by 5 1/8" (132mm) W by 5¾" (…
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Sidebar 1: Specifications
Sidebar 2: Measurements
The Optimus CD-3400's maximum output voltage from its line outputs was very low, measuring just 720mV when reproducing a full-scale, 1kHz sinewave. This is nearly 9dB lower than the standard 2V output level, and, coupled with a measured output impedance of 1370 ohms across the band, suggests that the CD-3400 should not be used with a passive level control. The output impedance from the headphone jack was a much lower 15 ohms, but the maximum level (defined as 1% THD+noise) was still low at 900mV into 150 ohms.
Channel balance was an acceptable 0.11dB at…
The CD-3400 appeared to have some positive linearity error at low signal levels (fig.5), but I believe the measurement is dominated by noise. A player's noise adds energy to the DAC's output, making it appear as though the player has an increasingly positive error as the signal level decreases. Because the CD-3400 uses a 1-bit DAC (which has inherently low linearity error), I suspect that the CD-3400's intrinsic linearity is better than that shown in fig.5. Moreover, the gradually increasing positive "error" as the signal level drops suggests that noise is swamping the DAC's output signal.…
Sidebar 3: More measurements from November 1994 (Vol.17 No.11)
I measured the effects of three jitter-reduction devices on a digital processor with the Meitner LIM Detector (see Vol.16 No.1, p.114), which looks at the jitter on the word clock driving the D/A converter chip—the point where jitter degrades sound quality. In previous measurements, I've found that the greater the S/PDIF jitter, the greater the word-clock jitter. Although using the LIM Detector to measure the effects of S/PDIF jitter-reduction devices appears to be a step removed from measuring the actual device, it may…
Postscript: More Jitter Measurements
The solid trace in fig.10 is a high-resolution spectrum of the CD-3400's analog output made with the Miller Audio Research Jitter Analyzer several years after the Stereophile review was published. The player was decoding data representing a high-level 11.025kHz tone over which has been overlaid a low-frequency squarewave at the LSB level. The drive ran quite a bit slow, the absolute pitch being off by -651ppm, which explains Robert Harley's 1994 experience that the Audio Alchemy DTI•Pro was unable to lock to the CD-3400's S/PDIF signal.
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A letter in response wondered about the "knocking"
Can you hear me knocking?
Editor: It blows my mind that all of you talented people missed a major screw-up on the Radio Shack CD-3400 CD player.
If you play it through the headphone jack, you will notice a double clicking sound in the right channel during quiet passages. I would have let this go, attributing the fault to my falling asleep with the $9 "special" Radio Shack headphones in my ears and pulling the damn machine off my nightstand about a dozen times. Lo and behold, my buddy, (world-, or at least Bay Area-,…
Looking at the current digital scene is enough to confuse and confound just about anyone this side of Stephen Hawking. One can choose from standard "Red Book" CDs (16-bit/44.1kHz), DVD-As, DADs (24/96 DVD-Vs), SACDs, combination audio-video players and changers, upsamplers, oversamplers, and every possible agglomeration of the above. As the audiophile-grade universal player remains vaporware, if you want to keep moving forward you have to choose among the various format combinations. Ayre Acoustics' Charles Hansen made his decision back in 1998—DVD-Video—and has spent the last four years…
In spite of the fact that the D-1x bristles with advanced engineering, it retains Ayre's trademark tasteful, minimalist design, and was easy to live with and use. The Pioneer-sourced remote control offers the full complement of video-related functions, and while it was a bear to find the one button I was looking for amid the clutter, I soon learned where the most vital functions were. Unlike the rock-solid D-1x itself, the remote feels a little cheap and cheesy...but it's perfectly functional, so big whoop.
Optimizing
Getting the best sound out of the Ayre D-1x meant dealing with…
Power for its own sake was also now served well. Kruder & Dorfmeister's dub remix of Bomb the Bass's "Bug Powder Dust" (EU CD, The K&D Sessions, CD K7 K7073) had much of the slam and control displayed by the standard-setting Classé Omega.
The D-1x's strongest tonal suit was its exceptionally detailed and transparent midrange. Sinfonia Antartica features a multitude of woodwinds in the "Penguin" section of the second movement. The D-1x cleanly differentiated all of the instrumental colors, free of smearing or the sort of timbral indecision that some CD players exhibit with…
Sidebar 1: Specifications
Description: Solid-state DVD-Video/CD player. Frequency response: DC-20kHz, ±0.25dB. S/N Ratio: 113dB (unweighted). Dynamic range: 98dB (unweighted with 16-bit source), 113dB (unweighted with 24-bit source).
Dimensions: Player: 18" W by 5 1/2" H by 11" D. Weight: 25 lbs. Power supply: 13" W by 3" H by 8" D. Weight: 15 lbs.
Serial number of unit reviewed: 5K0003P.
Price: $8000 as reviewed (see text). Approximate number of dealers: 30.
Manufacturer: Ayre Acoustics, 2300-B Central Ave., Boulder, CO 80301. Tel: (303) 442-7300. Fax: (303) 442-7301. Web:…