Vintage

The subject of this month's 'Vintage Review' is from my own private collection of digital landmarks [which includes the first Bit Stream player, the Rotel RCD-865, re-tested in HFN Mar '16]. Sony's CDP-557ESD pre-dates the Bit Stream/bitstream PDM/PWM revolution but it represents a significant advance over the 16-bit linear CD players based on the non-oversampled, time-shared CX20017 DAC used in Sony's inaugural CDP-101 [HFN Jan '12]. This flagship 8x oversampled/18-bit player offered a spectacular 120dB rejection of stopband artefacts thanks to the high-order (brickwall) digital filter, but this is also expressed in the pre/post echoes visible in the impulse (time domain) response. The magnitude (frequency) response is very flat, with the merest –0.02dB drop at 20Hz and –0.12dB/20kHz, the former linked to an increase in the capacitor-coupled analogue output's source impedance from 190ohm/1kHz up to 354ohm/20Hz.

The output is single-ended only, but the 2.18V recorded at 1kHz/0dBFs is accompanied by a very generous 110dB A-wtd S/N ratio. Interestingly, while the player offers this wide S/N, and distortion is very low at 0.0002-0.0004% at this peak output (20Hz-20kHz), the player's low-level linearity is less impressive. Indeed, the compressive trend below –70dBFs reveals errors of +3dB at –90dBFs, so very low-level detail is rendered at a very slightly higher level than it should. This is reflected in the 'shape' of the distortion vs. digital level plot [see Graph 1, below] where THD is still higher below –20dBFs than would be achieved by modern players and outboard DACs. Such are the revelations of tests unavailable during the lifetime of the CDP-557ESD – including the jitter test [see Graph 2, below] that prove this player offered a state-of-the-art 125psec back in 1987-8. PM