Simaudio Moon Eclipse CD player Measurements part 2

The Moon Eclipse's analog output stage seemed unflappable, with only a faint trace of third-harmonic distortion apparent in the spectrum of a full-scale 50Hz tone (fig.6). Intermodulation products (fig.7) were also superbly low in level.

Fig.6 Simaudio Moon Eclipse, spectrum of 50Hz sinewave, DC-1kHz, at 0dBFS into 100k ohms (linear frequency scale).

Fig.7 Simaudio Moon Eclipse, HF intermodulation spectrum, DC-24kHz, 19+20kHz at 0dBFS into 600 ohms (linear frequency scale).

Levels of wordclock jitter were low. The Miller Audio Research Analyzer indicated a peak-peak level of 252 picoseconds, which is excellent. The spectrum of the jitter, taken with the HDCD filter, is shown in fig.8: All the data-related jitter products (red numeric markers) are well-suppressed, with most of the measured jitter resulting from a pair of sidebands at ±504Hz (purple "3"). However, the noise floor, at around the -127dBFS level, is higher than is usually found these days in top-quality CD players.

Fig.8 Simaudio Moon Eclipse, internal CD data, high-resolution jitter spectrum of analog output signal (11.025kHz at -6dBFS with LSB toggled at 229Hz). Center frequency of trace, 11.025kHz; frequency range, ±3.5kHz.

Repeating the measurement with the Eclipse fed by an external transport (not shown) dropped the noise floor by 5dB, though the jitter level rose slightly, to 262.5ps. This was almost entirely due to an increase in the level of the fundamental data-related sidebands at ±229Hz (red "3"). This will be due to the bandwidth limitation of the data transmitter, the data receiver, and the S/PDIF link joining them.

All in all, the Eclipse appears to be a well-engineered player. Its sole compromise arises from Pacific Microsonics' license-mandated 6dB reduction in MOL for non-HDCD discs. But, as BD found, this can be avoided by using an external datalink to feed the unit's data output to its input. The slight increase in word-clock jitter appears to be more than compensated for by the increases in dynamic range and resolution.—John Atkinson

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