Juwan HeaneyMYRYAD Z20 (BLSigurd SchummTaya UllrichACK), DAC,Dr. Lawrence Leuschke DVM DIGITALMertie Orn, OPTICAL, DIGITAGiles BrownProf. Rod Bogisich IIIL TO ANAMariam ShieldsLOGUE CONVERTEIrwin JonesDr. Roderick BarrowsR

Z20DAC

The Z20 Digital to Analogue Converter (DAC) provides the perfect solution to high quality reproduction of digital audio, from whatever source. It can be the interface between a PC, Mac or laptop and your hi-fi system, and it can provide a sonic upgrade to the stereo sound from your CD, DVD or Blu-Ray player.

The Z20’s design features:

• Coaxial (S/PDIF), Optical (Toslink) and USB (2.0) inputs
• All inputs 192kHz/24bit capable
• Asynchronous USB receiver isolates the Z20’s DAC from computer clock jitter, resulting in clean precise sound
• All sources, at any bit-rate, are asynchronously up-sampled to 192kHz/24bit for accurate reproduction
• High end Cirrus Logic CS4398 DAC chip – as used in Myryad MX CD players
• Myryadintelligent system operation with other Myryad products

The Z20 is the first Myryad product in the new Zmini Series – featuring similar styling to the new Z200s, but in a half-width case.

The environment within a PC or other computer is inherently noisy and digital audio output streams are subject to jitter. The Z20 DAC employs double isolation to ensure a clean audio signal from its USB input. First an asynchronous USB receiver is employed which re-times the audio data according to one of the two low-jitter master clocks (one for 44.1/88.2/176.4 kHz and one for 48/96/192 kHz). After that comes an Asynchronous Sample Rate Converter which up-samples all incoming audio streams (USB, coaxial and optical) to 192kHz/24bit. This further reduces clock jitter and produces a constant high speed data stream for the DAC chip itself.

The Z20 uses the same Cirrus Logic CS4398 DAC chip as Myryad’s high-end MXC7000 CD player. The CS4398 is a fifth order delta-sigma converter which delivers wide dynamic range, low noise and low distortion. It actually contains four separate DACs – with push-pull outputs for each of the stereo channels. Each output feeds a differential-input low-pass analogue filter using a high-speed low-distortion FET input op-amp, close-tolerance metal film resistors and precision polypropylene film/foil capacitors. This arrangement suppresses ground-related noise from the DAC and delivers the cleanest possible audio output. To ensure no degradation of this pristine audio signal there is no coupling capacitor in the signal path to the output jacks. Instead a second high-speed low-distortion FET input op-amp is used to provide a “DC servo” to eliminate DC on the line outputs.

The power supply employs a low-noise toroidal mains transformer with separate windings for analogue and digital circuitry. It is mounted inside a steel screening enclosure to reduce any magnetic interaction even further. The transformer is of a special low-idle-power design so the Z20 draws less than 0.5W of power in standby – without the need for a separate standby transformer.

A total of 10 separate power supply regulators are used in the Z20, each optimised for its own task. They ensure that high-speed digital processing devices are isolated from each other and that no noise from these circuits can affect the analogue audio side. There is a separate high-isolation power supply solely for the master crystal clocks to maintain the lowest possible jitter.