Rockna Wavedream Dac coming soon to the Uk @ BD-Audio

News
Categories:
Digital-to-analog converters
Rockna Wavedream Dac coming soon to the Uk @ BD-Audio

We are proud to announce our new Wavedream dac series. There are 2 main models : Edition (featuring Rockna RD-1 discrete dac modules) and Signature (featuring Rockna RD-0 discrete dac modules). Each version can be ordered in single ended or balanced configuration.

In addition to the Femtovox clock system, both Edition and Signature benefit from a new discrete output stage and improved power supply section. Naturally they have dedicated sections for digital and analog areas. There are 3 separate transformers, and all power supplies are low noise linear - no switchmode power supplies are used whatsoever. There are a total of 20 linear regulators inside the dac.RD-1 module has a 26-bit ladder structure, while RD-0 is a 27 bit ladder structure. Both are FPGA-based, meaning they have their own (upgradable) firmware. Playing around with off-the-shelf available chips is fun and certainly a good and economic way to produce good sound. But once you want to design a cutting-edge product, the off-the-shelf approach doesn’t apply. Naturally, a custom solution, freed from the limitation of the available chipsets, come into place, allowing us to design and build from the scratch an entire digital audio system.

All building blocks of the Wavedream DAC concerning digital processing are built entirely on a single piece of programmable silicon – a FPGA . With a FPGA, it’s internal hardware architecture could be described by a piece of software (actually, a very complex one). When upgrading the Wavedream with new frmware, you actually change it’s hardware. This system allows great flexibility, obsolescence protection and let us improve the sound of your dac by changing it’s internal architecture, or add new cool features, or improve the existing ones.

The Wavedream upsamples any material with a fixed rate of 16x. The dac modules will decode the digital stream with a rate of 768Khz, or 705.6Khz, respectively, according to input sample rate. We found this rate to be optimal for analog performance of the dac modules. Behind this simple multiplication factor (16x) lies a huge processing power. The digital filters are made with the combined effort of 58 DSP blocks, resulting into a impressive figure of 15 GMACS of processing power.

The developed filters are unique. They avoided standard Nyquist rate filters as they did not provide the expected performance for the dac. After lots of mathematical simulations and careful listening tests, they have created a custom Parks-McClellan upsampling filter. There are three variations available on current firmware: linear, minimum and hybrid phase. They are highly optimized filters, offering stunning performance with a large number of taps (5k), and they are different in regard of impulse response. For the linear phase, the ringing energy (Gibb’s overshoot) is equally split before and after impulse. Minimum phase type shows all this energy after impulse, while our special hybrid phase filter has a combined response between linear and minimum, exhibiting very low overshoot before the impulse.

Finally, the last stage of the signal path is the analog output stage. It’s contribution to final sound is of extreme importance. Designed from the scratch to work with converter modules RD-0 & RD-1, the output stage is totally discrete and acts as a high-speed buffer. Made entirely with through-hole components (non-smd), we combined j-fet & bipolar devices into a class A design, with a closed-loop output impedance of under 1 ohm and equivalent input noise as low as 1nV, as a perfect match for the converter overall performance.

blog comments powered by Disqus

Featured Articles