Varèse: Our Most Ambitious Undertaking…
 
Varèse is the most advanced dCS system to date. Here, we explain how our engineers set new standards in measured and sonic performance, developing new technologies, protocols and platforms to bring listeners an even more profound musical experience... Varèse builds on a long tradition of innovation at dCS. It is the most advanced, bestperforming system we’ve ever created, and sets new benchmarks in a range of key areas, from noise floor to jitter performance. Our most ambitious undertaking yet, it reflects our dedication to preserving the integrity of musical signals at all stages of the signal path – and the extreme lengths we go to in order to achieve this. It is the culmination of several multi-year development projects, undertaken with a single aim: to further enhance the musical experience we provide, and bring listeners an even deeper connection with the music they love. Here, we provide a more detailed look at the new innovations and technologies Varèse presents, explaining how our engineers were able to exceed the capabilities of existing products and platforms and once again advance the state-of-the-art in digital audio.
 
A New Architecture: The Varèse Mono DACs
All current dCS DACs – including APEX models – feature 96 current sources: 48 for the left channel and another 48 for the right. Each current source generates an equal amount of voltage and is operated to distribute any component errors (tolerances in resistor values) in the current sources as random noise instead of harmonic distortion. The current sources are located on a single Ring DAC board within the DAC, with the left and right channels separated on the board. With Varèse, the left and right channels have been separated into ‘Mono DACs’, with an entire DAC unit for each audio channel. This allows for several significant improvements to be made. Some are general engineering improvements. Others are advances made possible with the development of new proprietary technologies.
 
Each Varèse Mono DAC features 96 current sources. This means there are now twice as many current sources for each audio channel. These current sources are fed a 5-bit PCM signal synchronously modulated to either 5.644MHz or 6.144MHz, depending on the source content’s sample rate.
 
The Differential Ring DAC: Overview The Ring DACs in Varèse are run in a differential architecture. The 96 current sources on the Ring DAC board are split into two groups of 48, with one group reproducing the musical signal in the correct phase and the other reproducing the signal in antiphase. The outputs of these two sets of current sources is differenced, meaning the phase of the antiphase current sources is reversed and summed together with the correct phase current sources.
 
One set of 48 current sources generates the analogue signal in the correct phase.
 
The second set of 48 current sources generates the same analogue signal, but in antiphase.
 
The output of these two sets of current sources is differenced, resulting in the correct phase signal at twice the amplitude with no DC offset.
 
The differential operation means any noise or nonlinearities created in the Ring DAC are effectively removed from the output.
 
Differential Ring DAC Advantages & Benefits Running the Ring DAC in this differential manner brings several benefits: • Balances draw on reference supply* *The reference supply is the voltage which is fed to the current sources. This gets multiplied up by however many current sources are switched on. Anything other than clean DC being fed to the current sources is also multiplied up – where the correct phase side of the Ring is at a higher voltage, the antiphase side is at a lower voltage. This means that the draw on the reference supply is not signal dependent, as both sets of current sources are working in a complementary manner. This removes a mechanism for second harmonic generation within the Ring DAC, improving distortion performance. • Equalises the offsets on each summing node, eliminating the need for explicit DC offset correction and improves the symmetry of the summing / filter circuit All processing and analogue functions within each Varèse Mono DAC are carried out on a single board rather than multiple boards connected together. This enables us to improve on several design aspects and ensure an even more consistent performance. This approach builds on the single-circuit design first seen in the dCS Lina Network DAC – a design that came out of early Varèse research and development work. Running dual Mono DACs, each with a dedicated Differential Ring DAC architecture, has enabled us to further reduce distortion while simultaneously lowering noise floor by 5dB, setting a new reference in measured performance and building on the exceptional capabilities of the Ring DAC APEX – another innovation that stemmed from development work on Varèse.
 
Hardware Innovations In addition to developing a new DAC architecture, dCS engineers have made a range of improvements to our DAC hardware to further improve performance and ensure ultimate audio quality.
 
These include:
• Enhanced Power Supplies
• Optimised Transformers
• Improved Secondary Circuits
• New Regulator Topology
• Additional Regulation for Analogue Supplies