Marantz CD5004 CD player Marantz CD5004 CD player Measurements
Sidebar 3: Measurements
I used Stereophile's loan sample of the top-of-the-line Audio Precision SYS2722 system to perform the measurements on the Marantz CD5004 (see www.ap.com and the January 2008 "As We See It"). For some tests, I also used my Audio Precision System One Dual Domain and the Miller Audio Research Jitter Analyzer.
The Marantz's maximum output at 1kHz was 2.35V, which is 1.4dB higher than the CD standard's 2V. Unless compensated for, this will be audible in comparisons with other players. The output preserved absolute polarity (ie, was non-inverting), and was sourced from a fairly low impedance of 202 ohms. The error correction was excellent, the CD5004 playing, without audible glitches, all tracks on the Pierre Verany Test CD up to track 34, which has 2mm gaps in the data spiral. However, monitoring the error flags in the digital output with RME's DIGICheck program revealed that there were occasional interpolated errors from track 31, which has 1mm gaps, onward.
The frequency response was flat over most of the audioband, with a slight drop to 0.25dB at 20kHz (fig.1, blue and red traces). There was very slightly more top-octave energy with preemphasized data (fig.1, cyan, magenta). Channel separation (not shown) was superb at >120dB in both directions at all frequencies. I tested the Marantz's resolution by playing a dithered 1kHz tone at 90dBFS from CD while sweeping the center frequency of a 1/3-octave bandpass filter from 20kHz to 20Hz; the resulting spectrum is shown in fig.2. The traces peak at exactly 90dB, suggesting minimal linearity error. Other than a small bump centered at the power-supply frequency of 120Hz, the noise floor in this graph is actually that of the recorded dither used to encode the signal. Repeating the analysis with an FFT technique and a linear frequency scale gave the spectrum shown in fig.3. The supply-related spuriae are low enough in level that they will be inaudible under all circumstances.
Fig.1 Marantz CD5004, frequency response at 12dBFS into 100k ohms (left channel blue, right red) and with preemphasized data (left cyan, right magenta; 0.25dB/vertical div.).
Fig.2 Marantz CD5004, 1/3-octave spectrum with noise and spuriae of dithered 1kHz tone at 90dBFS with 16-bit data (right channel dashed).
Fig.3 Marantz CD5004, FFT-derived spectrum with noise and spuriae of dithered 1kHz tone at 90dBFS with 16-bit data (left channel blue, right red).
Plotting the amplitude error against absolute signal level gave a curve that was dominated by the dither, so I haven't shown the graph. But with the CD5004's minimal linearity and a noise floor well below that of the CD medium, it came as no surprise that its reproduction of an undithered signal at exactly 90.31dBFS was perfect (fig.4). The waveform in each channel is superbly symmetrical, and the three DC voltage levels described by the data are well resolved.
Fig.4 Marantz CD5004, waveform of undithered 1kHz sinewave at 90.31dBFS, 16-bit data (left channel blue, right red).
The CD5004 is well capable of driving low impedances with very low distortion. Even into the demanding 600 ohm load, the highest-level distortion harmonic, the third, remained at 94dB (0.002%), with all other harmonics below 110dB (fig.5). The Marantz did similarly well on the high-frequency intermodulation test, with all distortion components below 100dB (0.001%, fig.6).
Fig.5 Marantz CD5004, spectrum of 50Hz sinewave, DC1kHz, at 0dBFS into 600 ohms (left channel blue, right red; linear frequency scale).
Fig.6 Marantz CD5004, HF intermodulation spectrum, DC24kHz, 19+20kHz at 0dBFS into 100k ohms (linear frequency scale).
Finally, the CD5004 offered superb rejection of word-clock jitter, with the odd harmonics of the LSB-level, 229.6875Hz squarewave lying at the residual level, and only pairs of sidebands at ±60 and ±120Hz visible to the sides of the 11.205kHz tone in the narrowband spectrum of the Marantz's output while it played the Miller/Dunn J-Test signal (fig.7). I haven't given a numeric figure for the player's jitter level, as it was below the Miller Analyzer's resolution limit.
Fig.7 Marantz CD5004, high-resolution jitter spectrum of analog output signal, 11.025kHz at 6dBFS, sampled at 44.1kHz with LSB toggled at 229Hz: CD data (left channel blue, right red). Center frequency of trace, 11.025kHz; frequency range, ±3.5kHz.
The Marantz CD5004's measured performance indicates that its intrinsic resolution is better than is needed by the CD medium. That it can offer this level of performance for just $350 is astonishing.John Atkinson