Meet Your Maker: Hi-Fi+ Visits CAD (Computer Audio Design)

Digital-to-analog converters
Meet Your Maker: Hi-Fi+ Visits CAD (Computer Audio Design)

Last year I reviewed the CAD 1543 DAC, the first product from a new company that made a deep impression on me and remains one of the most revealing converters available. In February, CAD (Computer Audio Design) made its hi-fi show debut at Sound & Vision Bristol and carried off the Clarity Alliance Best Stereo Sound of the event for its troubles. That company was founded by Scott Berry, a purist audiophile whose converter eschews all digital connections save for USB and even has a captive mains lead. I asked Scott about the thinking behind the 1543 DAC.

JK: What prompted you to build a USB only DAC?

SB: I didn’t like the sound quality of most of the digital sources I could afford – and many of those I couldn’t! I started experimenting with DACs for my own use, and like many others, I started off with an S/PDIF interface. However, as I began working with some of the early good USB interfaces I found that I couldn’t match the sound quality I was getting from a USB interface with the S/PDIF. At the same time, I formed the opinion that audio in the future will be more computer-based: as broadband speed increases, music sales are moving from CDs to downloads, and as memory is becoming cheaper uncompressed higher resolution file formats are becoming more practical.

What do you do that’s different?
I am an electrical engineer and worked for many years at Tektronix in the USA and then Xerox. I did quite a bit of work in high frequency design and that experience has helped me with the 1543 DAC. In general my approach was based on educated trial and error, and a lot of listening. I am not a believer in using measurements as an indicator of sound quality. There isn’t a measurement that can confirm that sound quality has ‘improved’. The best measurement tool we have for audio is our ears and in general we spend far too much time looking at specifications and measurements than actually listening.

You want as few connections and components as possible in the mains power path and the digital and analogue signal paths. The 1543 DAC has a hard-wired power cord, because even the best IEC connector degrades the sound. This design philosophy is carried throughout the DAC.

In digital audio, I feel power supplies are crucial, at least as important as the DAC chips! I don’t use ‘off the shelf’ voltage regulators, there are five independent power supplies using independent transformers and discrete parts.

The 1543 DAC case is made entirely from acrylic. Early on I had prototypes in aluminium cases, I then made a similar case from acrylic and compared the sound quality. Everything inside the two cases was exactly the same and I couldn’t believe the difference in sound quality; I much preferred the acrylic case.

The output of all source components is voltage. The TDA1543 DAC chips output current that then has to be converted to voltage. Many designers use tubes, transistors or operation amplifiers to perform this task. I find a ‘passive’ single resistor and a DC blocking capacitor produces a sound that is more natural.

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