Wagner Audio Labs Super R2R DAC

Another very interesting DAC implementing patented Super R2R technology. This time coming from Wagner Audio Labs - Russia. Find below official technical description...

Super R2R technology successfully combines several new digital-to-analogue conversion technologies developed by WagnerAudioLab. This technology enables DACs to sound in a truly realistic way for the first time in HiFi history.

We’re firmly convinced that any attempt to obtain high quality sound from a traditional microchip converter is doomed. The ultimate solution to this problem is Super R2R technology created after many years of research and numerous experiments with diverse circuitry.

Super R2R consists of:

1. Converter based on R2R circuit
R2R circuit is a classic converter layout realizing the most accurate way of digital-to-analogue conversion.

The sound of R2R array based converter without oversampling (NOSDAC) is more natural than the one achieved by means of other circuits with oversampling and digital filtering. Unfortunately all converter chips currently manufactured work with oversampling and digital filtering. Most DACs are based on these chips.

On the other hand we have to admit that a high quality R2R converter is a complicated and a fairly expensive device. That’s why all the other technologies used in abovementioned chips are nothing but attempts to simplify schematics, but this approach leads to sound deterioration.

2. Balanced R2R array circuit
Classic R2R array has a flaw associated with the problem of signal conversion while virtual zero crossing. At this moment all logical circuits are switched simultaneously and even tiny non-synchronism causes an overshoot of stray impulses (the so called glitches).

In Super R2R virtual zero crossing poses no problem because R2R arrays have balanced circuitry. Positive and negative half-waves of the signal are processed independently, each by a separate array and are mixed only at the output (Fig. 2). As the result there’s no virtual zero crossing at all and no corresponding problems!

Besides if we use two identical R2R arrays we get a proper not a fictitious balanced circuit. By the way a balanced circuit is used not only in Dream DAC converters but also in the signal path of all WagnerAudioLab products.

3. New synchronous volume control
Any audiophile knows about the existence of two fundamentally different approaches to volume control — a digital and an analogue one; each has its own major flaws. The classic solution is to control analogue signal level in a pre amp. In this case the sound strongly depends on the quality of potentiometers used and there’s no way to get rid of noise and distortions completely.  

Digital volume control is no better. Such meddling in the original digital signal leads either to of dynamic range contraction or to distortions that rob the sound of its naturalness.

WagnerAudioLab designed a new way of volume control suitable just for the R2R array. It’s neither digital nor analogue in the current interpretation of these terms. It is based on synchronous changing of the logic value of ‘1’ reference voltage in the converter and enables to control volume without changing original digital code. At the same time is has no drawbacks inherent in the analogue control method.

DreamDAC based on the circuitry which works according to abovementioned principles has many significant advantages. First, it makes pre amp and passive volume control superfluous reducing noise and distortion these units would otherwise have brought to the sound.
Second, it shortens the signal path from source to speaker. We can say without any exaggeration that for the first time ever WagnerAudioLab have the shortest signal path currently feasible.

4. A new algorithm for low level signals conversion
This new algorithm enables to fulfill the sound potential of low amplitude signals that otherwise are reproduced either with distortion or remain completely obscured by noise and inaudible.

The new algorithm for low level signals conversion is realized by means of a three-stage circuit; a single R2R array is divided into three parts. Each part is a separate R2R converter processing its own fraction of the signal — having either low, medium or high level. The low level signal ends up being shaped by a chain of not 24 resistors the way it’s done in the conventional R2R converter (with 24 digit capacity) but by 8 resistors only resulting in a dramatically shortened signal path. This technology provides for a careful handling of any low level signal.

Besides the digital code’s least significant bits get an additional gain before conversion and are again brought to normal level afterwards.

All in all the new algorithm makes the low level signals noise-free and maximizes DA conversion authenticity in the most important area of low amplitude signals.

Taking into account the three-stage balanced circuitry the converter uses in total twelve R2R arrays. They work in parallel — six in each channel. 5 Galvanic decoupling of digital and analogue converter units
Galvanic decoupling by means of a transformer provides for a full separation of digital and analogue converter circuits preventing from sound quality deterioration by noise and distortions.   

Super R2R technology enables to achieve not only the absolute sound fidelity but also — probably — the ultimate quality level obtainable by digital-to-analogue conversion in principle.
Not long ago one could only dream about a DAC sounding as good as that. That’s why WagnerAudioLab converters using SuperR2R technology bear the name of DreamDAC.

All DreamDACs manufactured by WagnerAudioLab are designed on the basis of Super R2R technologies.

Super R2R technologies are protected by patents and applications for an invention.