Vintage

Aside from the transport and PD4184 microcontroller – used to manage the display, key functions and the switching between transport trays – the PD-Z72T’s core digital audio technology is largely outsourced (the likes of Legato Link digital filtering were yet to come). Specifically, a Sony CXD1130QZ decoder deals with the digital data, and even includes a basic 2x oversampling filter, before being addressed to a Sanyo LC7881 dual-channel 16-bit DAC. The integrated 2x digital filter is a limited-tap linear phase type that rolls off slightly early (above 18.5kHz) to achieve –1.2dB/20kHz [Graph 2, below] but the series analogue filter is very gentle so overall stopband rejection remains a poor 5.5dB. At the player’s 1.9V maximum output, delivered from a ~900ohm source impedance, the A-wtd S/N ratio is a usefully wide 103.5dB even though the DAC’s linearity is skewed below –90dBFs with signals at –95dBFs appearing some 3.9dB higher in amplitude.

Digital jitter is dominated by data-induced sidebands at 630psec and while this is a moderate figure, the PD-Z72T is otherwise free of low-rate effects, including uncorrelated phase noise – distortions that can have an adverse effect on the sharpness of stereo soundstaging. Stereo separation is also wide – at least 100dB through the midrange and 75dB at 20kHz. Distortion is extended to the 10th+ harmonic through bass and midrange, amounting to 0.025%/1kHz at peak output and generally – if rather erratically – increasing with decreasing digital level [see black trace, Graph 1]. High frequency distortions peak at 0.4%/20kHz, where there’s also a strong intermodulation with aliasing signals, but falls to as low as 0.016% over the top 20dB of its dynamic range [blue trace, Graph 2]. PM