Design Vision

With digital audio entering the mainstream (of current High End Hi Fi appreciation), more and more recording and distribution are done in digital format. Among the different storage and transport media, the compact disc (CD) is by far the most popular because of its robustness and convenience. This cultural movement has created a huge demand for quality Digital-to-Analog conversion devices to facilitate the play back of the audio signal stored on the CD.

Further, the sound quality from the upcoming audio standards, SACD and DVD-Audio, has not been widely endorsed by the industrial or the audiophiles. In actual of fact, lots of customer commented that the CD produces a more musical sound overall.

There is no shortage of DAC and CD players in today’s market, but not every manufacturer can deliver 100% to his performance promise. When in pursuit of higher profit, design visions are often compromised to give way to cost saving measures such as reducing PCB layers and using sub-standard components. Some “Hi-End” manufacturer uses generic DVD player as the base of their High-End CD player.

  =>  

Generic DVD player                 High-End CD Player

In a sharp contrast, the DAC2488 is designed and engineered from ground up to meet the extraordinary standard of the most demanding audiophiles. With precise engineering and detailed craftsmanship DAC2488 deliveries a true high-end performance

Digital-to-Analog Conversion (DAC)

Figure 1 illustrates the process of converting digital signal into analog signal. It is a simple process that can be accomplished with the help of a few off-the-shelf electronic parts, yet the quality of the output signal can vary a lot with different system designs. In order to distinguish a good system design from a generic one, a basic understanding of the system building blocks becomes essential.

Digital Receiver
The Input Receiver is the digital interface with will receive a digital signal from a CD Transport; it provides the functions of data extraction, control and user bits extraction, incoming frequency measurement, error detection and correction, and low jitter clock generation and regeneration.

Digital Filter
The digital filter is used to reduce phase shifts, and to improve signal to noise ratio. It is used at the input of the D/A converter to suppress the frequency spectrum immediately above the audio band. In this particular application, digital filter is preferred because it does not produce the sharp cutoff output normally found with analog filters.

Digital-to-Analog Converter
The D/A converter are used to convert the digital signal to an analog current signal. In general, system with the higher number of bits has lower noise, better linearity, improved dynamic range and lower distortion.

I/V Converter
Because the output signal of D/A converter is in the form of a current, an I/V converter (usually an integrated function of the OP-AMP) is used to convert the current based signal into a voltage waveform.

Low pass filter
Used at the final stage of the D/A conversion process, a low-pass filter reconstructs the analog signal from the original digital sample and smoothens the output waveform for further processing or amplification.