DCS RING DAC

Data Conversion Systems writes: “The dCS Ring DAC is a unique digital-to-analogue conversion system that sits at the heart of all dCS products. Designed like no other DAC, it reduces jitter and distortion to vanishing levels, providing an experience that resolves all aspects of sound – from the finest of musical details, to the sense of time and harmonic movement.” 

Digital to Analogue Converters, or DACs, are a fundamental part of all digital audio systems. The purpose of a Digital to Analogue Converter in the context of a digital music playback system is to convert the digital audio data stream to an analogue signal. This analogue signal is then fed to transducers such as loudspeakers or headphones for listening. The DAC is an integral part of the playback chain, and has a profound impact on how we experience music.

The process of converting 1’s and 0’s into an analogue wave generates unwanted artefacts, or ‘noise’. Common DAC topologies often correlate this ‘noise’ with the actual signal. This leads to distortion being created, which is then introduced into the music we hear. This distortion comes in the form of added harmonics, which the human ear finds difficult to ignore as harmonics are fundamental to how we hear and interpret music.

The dCS Ring DAC is a groundbreaking DAC that is unique in its design and peerless in its performance. Combining exceptional noise performance with vanishingly low distortion, ultra-wide bandwidth and very low jitter, the Ring DAC does not impose our view of the musical world on the 1s and Os it receives. Rather, it provides a virtually limitless performance envelope that provides a mirror to the recording, faithfully serving the musical message as the artist intended.

Revolutionary thinking

With the Ring DAC, we’ve engineered the most advanced and accurate digital-to-analogue conversion system available: a unique combination of hardware and software that resolves all aspects of a musical recording, from the finest of details, to the sense of time and harmonic movement.

On the surface, the Ring DAC may look like a Ladder DAC. There is a latch and a resistor for each current source, and these current sources are fed to a summing bus. The key difference between the Ring DAC and Ladder DACs, however, is that the Ring DAC uses current sources of equal value. This is what is known as a ‘unitary weighted’ or ‘thermometer coded’ DAC architecture. Additionally, the Ring DAC does not use the same current source(s) for the same bit every time.

Given that any combination of current sources can be fired for any bit in the Ring DAC, the error generated is completely unrelated to the audio signal; it is decorrelated. This decorrelation means that any errors are randomised and converted to white noise.

This approach reduces distortion to vanishingly low levels, avoiding the nonlinearities that can obscure low-level details that are so important in our understanding of a musical event.

Rewriting the rules

The nature of exactly how the Ring DAC decides which current sources need to be turned on or off at any given point to generate the correct signal is dictated by a highly sophisticated set of mathematical rules defined in the dCS Mapper. While it might appear to be random, this process is the culmination of three decades of continuous work, resulting in a carefully calculated set of patterns designed to minimise noise, distortion and crosstalk, while also keeping the highest degree of linearity by averaging out the contribution of noise-inducing components that fall out of specification over time.

Improvements to these proprietary mapping algorithms, as well as increases to the speed at which the Ring DAC operates (from 2.822 mHz to 6.14 mHz), have been provided to dCS owners through a series of software updates, ensuring it remains unrivalled in its performance and ability to take you to the heart of a recording. This software-based approach to DAC design means that our engineers – who are constantly exploring ways to improve the performance of both the ring and the output stage – can simply update the Ring DAC through software whenever new discoveries and advances are made.

Exhaustive development

Analogue design is as important to dCS as digital and is another factor that contributes to the Ring DAC’s technical and musical superiority. A number of techniques are employed by our talented and experienced engineers to create state-of-the-art analogue performance. One example of this is the use of Compound Amplifier Topology in our hardware design, which involves cascading two op-amps to form a single amplification stage. This has a number of advantages: an op-amp can be chosen for the input stage with very good input characteristics, and an op-amp chosen for the output stage which has very good output characteristics. This is useful as it is quite unusual to find a single part that is equally effective in both input and output performance.

Additionally, this combination delivers more gain, so more feedback can be applied for improved linearity. The result is extremely low harmonic distortion, extremely low noise, and generally exceptional overall performance. Fundamentally, the D/A core of the Ring DAC is extremely linear, and it is important that the surrounding analogue design does not degrade that linearity.

PCB layout is also important, and a great deal of attention is paid to it at dCS. Quite often, there are unusual and unexpected interactions that occur between elements on a circuit board. This is where dCS’s strict measurement regime, which includes bespoke test equipment developed in-house through our experience in radar and broadcast, is instrumental in identifying when something is occurring that should not be and tracking down the source.

From power supplies to signal routing, component placement and current steering, each aspect of the Ring DAC’s design and layout is carefully considered and meticulously crafted to provide the finest possible performance, and a musical experience that feels both lifelike and beautifully complete.