Vintage

As Tim describes in our review, the technology inside the CDP-C5M is illustrative of a short-lived stepping stone in Sony's digital journey. The impulse response [inset, Graph 2] shows the pre-ringing associated with a basic FIR 2x oversampled digital filter with coefficients that look very close to those employed in the D-88 portable [HFN Jul '16], launched just a few months later. This is combined with a relatively relaxed analogue filter in the CDP-C5M, yielding a mere 24dB stopband rejection and a frequency response with a slightly attenuated presence/treble and uptilted high treble of –0.2dB/12kHz and +0.24dB/18.5kHz, respectively. The limited tap length of this linear phase filter is also reflected in the ±0.06dB ripples seen in its passband response – a feature better suppressed in Sony's next-gen 4x oversampled players. Also, the 1.7V output level is some –1.4dB lower than the norm while the 2.2kohm impedance is really too high.

The 16-bit PCM56P DAC brings its own 'character' to the ensemble in the form of a slight step or 'kink' in its low-level resolution at –80dBFs. This is also visible in the THD vs. digital level trend [Graph 1, below] which also shows the close parity of distortion between midband and very high frequencies (~0.004%/0dBFs and ~0.015%/–30dBFs) something rarely seen these days as digitally-derived distortions are typically much lower and where HF THD is more often set by the associated analogue stages. So, in this case, the player's linearity is good to ±0.5dB over the top 80dB of its dynamic range but with a +2.5dB error below this. At the time, Burr-Brown graced this DAC with a 15-bit monotonicity, a figure that also corresponds with the 93.5dB A-wtd S/N ratio measured here over 30 years later. Jitter, meanwhile, is impressively low at 245psec. PM