Tuesday, October 22, 2013

Vertex AQ Aletheia dac-1.5

















The Aletheia dac-1.5 is identical to the dac-1 in terms of topology and architecture. It has all the same major components as the dac-1, in the same modules, mounted in the same physical layout. All the power supply parts including transformer and regulators are identical, as is all the digital processing circuitry and analogue outputs – except in three critical ways as follows:

At many key points in the circuits, where quality of resistors has an effect on performance, the standard carbon resistors are replaced by Charcroft ‘Z’ foil resistors. And because the ‘Z’ foils are a naked design, we apply anti-vibration technology right onto the core structure of the resistor. Some of the key locations where we have done this are: digital input load resistor, data line resistors, output I/V resistors and many of the important resistors in the various voltage regulators.

Instead of using the Mundorf metallised polypropylenes (silver/gold/oil) as employed in the dac-1, we use the solid copper foil Duelund VSF capacitors in the analogue outputs.

The dac-1.5 has much more comprehensive anti EMI and anti-vibration technology applied internally to the case. This lowers even further the influence of the case, and the intrusion of the outside environment, on the delicate internal signal processing.


Technology

The fundamental All internal wiring is fitted with EMI absorptive tubing, and all wiring downstream of the mains transformer is solid-core silver. The major components of the design are housed in separate modules, each with EM absorptive linings and acoustic absorption. The mains transformer and pre-regulator modules are fixed on compliant mountings. Within the modules, acoustic absorption is applied to individual components.

The mains input has a built-in RFI filter (a shunt filter – so nothing in the current path), and input/ output signal lines each have an internal RFI/ acoustic absorption module fitted, and signal sockets are mounted on isolated sub-panels.

An ultra high-speed, dual-stage power supply topology is used. A pre-regulator feeds 4 discrete component second-stage shunt regulators to separately feed each processor supply. The regulators are from Paul Hynes Designs, with extensive anti-RFI/EMI and acoustic treatments applied in-house.

Each analogue output is taken straight out of the DAC chip and converted to a voltage signal passively, across the ultra high-quality Charcroft resistor (known as passive I/V conversion) – so no active output stages. Output capacitors are the superb Duelund CAST capacitors (solid copper foil).

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