Arcam FMJ CD23 CD player Measurements

Sidebar 3: Measurements

The smart-looking FMJ's output level was 2.34V, almost 1.4dB above the standard 2V RMS—something to be aware of in A/B comparisons. Its output was absolute-polarity-correct and its source impedance was a low 47 ohms across the audioband. Its error correction was superb, the player not mistracking until the Pierre Verany test CD's track 34, which has 2mm gaps in its data spiral.

Fig.1 shows the CD23's frequency response without (top traces) and with pre-/de-emphasis (bottom), which is flat and almost perfectly balanced between channels. There is a slight response rise in the top octave, but the de-emphasis error is otherwise nonexistent. Crosstalk between the channels (not shown) was buried beneath the noise floor below 2kHz, but rose to a maximum of just -94dB (R-L) and -82dB (L-R) at 20kHz, which is excellent.

Fig.1 Arcam FMJ CD23, CD frequency response with (top) and without (bottom) de-emphasis at -12dBFS (right channel dashed, 0.5dB/vertical div.).

The spectrum of a dithered 1kHz tone at -90dBFS (fig.2) was free from spuriae other than the power-supply-related tones at 60Hz and 180Hz, presumably due to magnetic coupling from the transformers into the audio circuitry. These are still very low in level, however. Fig.3 extends the analysis bandwidth to 200kHz and the test signal to digital "black." Any rise in ultrasonic noise is negligible.

Fig.2 Arcam FMJ CD23, 1/3-octave spectrum of dithered 1kHz tone at -90dBFS, with noise and spuriae, 16-bit data (right channel dashed).

Fig.3 Arcam FMJ CD23, 1/3-octave spectrum of digital black, with noise and spuriae, 16-bit data (right channel dashed).

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