Audio-GD – R8 MK2 (EC) – Discrete Balanced R2R Ladder FPGA Accusilicon DAC

REVIEW(2019 model)

AUDIO-GD R-8 MK2

MK2 Version

R-8 MK2 edition: IN2 BNC input is the BNC coaxial s/pdif input .
R-8 EC edition: IN2 BNC input is an external 10MHz 75ohm input to connect a Master Clock  (Supports 1-3V p-p 10Mhz sine & square wave – square wave recommended)

This MK2 version of the R-8 has undergone a long period of testing, measuring, listening and adjusting at all levels of the circuit. It uses a stabilized power supply using discrete servos for battery-like performance. The converter stage uses this stabilized power supply, where analog circuits use a pure Class A power supply.

• Discrete in-house developed 3rd generation R2R discrete ladder technology
• 4 independent hardware DSD decoders and 8 independent R2R PCM decoders
• Balanced two-channel push-pull design
• Ultra low noise Power Supply design (battery performance)
• Special “vinyl” sound characteristic available
• USB and HDMI inputs have independent isolators and linear power supplies
• USB designed with bidirectional isolator that sends the I2S signal to the FPGA and receives the return master clock signal. (single clock approach)
• Sample rate on display of the input source
• Two Accusilicon clocks working at 90Mhz and 98MHz master clock implementation.
• DSD signals use an asynchronous clock for greater accuracy.
• A port for updating the firmware is available on the back of the device.

R8 is characterized by its coherent, transparent and neutral sound. Rich in detail; high resolution; strong authority and wide stereo image. You’ll forget that you’re listening to a digital source.

SPECIFICATIONS

ANALOGUE OUTPUT STAGES

The analog output stages are as important, they have a tremendous influence on the final sound quality. After d/a conversion by the R2R D/A modules the analogue signal is transported by fully discrete matched-transistor output stages; DC-coupled design with first class through-hole components. No SMD compon ents are applied in the analogue section.  The high speed unique ACSS ((Audio-gd Current Signal System) output stages are non-feedback and current driven. Unique performance because almost all other designs need to convert the signal multiple times from and to current and/or voltage, resulting in less detailed and less transparent sound-stage The output buffers are single ended FET; two stages in parallel to reach very low output impedance. All output stages are in pure class A without (negative) feedback to achieve purest and a real live sound reproduction. The 4 OPA op-amp’s are DC servos, this way no coupling-capacitors are needed and DC output is automatically biased. The listener will be presented a strikingly transparent and neutral sound.

ACSS – Current Amplification

Audio-GD has developed an advanced current-driven amplifier technique. Also known as ACSS, Audio-GD Current System Signal. This special technique ensures that the signal travels a much shorter path and that ensures a more transparent, faster and more neutral reproduction. A similar technique is used by, for example, KRELL. The Current Conveyor technology mostly components are the current mirror. The Current Conveyor technology isn’t a new technology, at 1966 , professor K.C. Smith and A.S.Sedra publish the concept “current mode analogue circuits “ .

CLEAN POWER

The DAC consist of 3 tuned low noise, low flux leakage, R-cores transformers. In total 130W power to supply all digital parts and the left and right analog boards. The DC power is distributed over 19 separate power regulators. All are pure class A low noise shunts; fed by 3 groups linear power supplies. Resulting in ultra-high speed and clean power for all individual parts.