Acousticbuoy DAC2488 multi-format Digital to Analog Converter
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PCB and Power Layouts

In the DAC2488 design, digital signal processing and analog signal processing are done separately on 2 printed circuit boards to minimize cross interference. And further reduce of the interference arises from digital-to-digital transformation, digital-to analogue conversion, and pure audio playback (separate L & R Channel and SNR), 4-layers PCB are used throughout the design.

Even the noise performance particular for analogue stage, 4-layers PCB have better result that compared with the common double and single layer of PCB system.

In the DAC2488 power design, the transformer for digital operation is also separated from that of the analog operation to reduce electro-magnetic interference.

Isolation and Vibration Control

The last type of interference we try to bring down comes from the vibration of the system. The type of vibration could be generated by the transformer of the power supply, or by the compact disc transport. And when acoustic energy impinges on the electronic components, it will create a so-called “micro-phony” phenomenon, and cause degradation to the audio performance.

Micro-phonic component emits a small electrical signal when it vibrates; and acts as a microphone converting kinetic energy into electrical energy. This electrical energy pollutes the audio signal in audio system and degrades the sound quality. As all electronic components are micro-phonic to some extent, digital systems are not immune from this micro-phony problem. For instance, the crystal oscillators in a digital system may change their frequencies slightly when vibrate, this could cause a small frequency shift and clock variations, and can wreak havoc in the forms of jitter and data error.

To minimize the micro-phony effect, vibration-isolation accessories such as spikes or cones are often used to reduce vibration in an audio system. In the design of DAC2488, two methods are used to minimize the micro-phony effect. The first method is to house the system inside a sturdy chassis build with thick aluminum planks; 6mm for the side, top, and bottom panels, and 8mm for the front panel to cut down vibration generated by the system itself. The second method is to layout the spikes or cones in a triangular shape as shown in the diagram below, to make use of the geometry to keep the system in a stable position.