Audio-GD - R2R2 - Discrete Single Ended R2R Ladder FPGA DAC - PCM / DxD / DSD
Single-ended digital analogue converter, equipped with multi discrete R-2R ladder per channel. All parts and components are selected based on excellent sonic and technical measurement performance. Components are e.g. from DALE resistors (USA), WIMA capacitors (Germany) and NOVER parts (UK). The used components but also the technical design (e.g. discrete analogue section and high speed FPGA's) of this system were being selected after many years of experience and practices and are considered to perform and provide supreme sonic results. Supporting today’s high resolutions including DSD and DxD and up to date interfaces like USB and LVDS I2S.
- Dual R-2R discrete dac ladder per channel
- Integrated 2 pairs of DA-8 R-2R modules
- 2x ultra low-jitter TCXO clocks are included
- Amanero Combo384 USB interface
- USB Amanero Combo384 interface
- Programmable hardware design
- Single ended output design
- High speed FPGA's to control R-2R network
- Lowest tolerance Vishay resistors applied in R-2R network
- Discrete analogue output & power supply
- Fully DC coupled design without capacitors in signal path
- Non- feedback ACSS analog output control
- Total of 5 regulated low noise class A power circuits
- 1. RCA coaxial SPDIF
- 2. USB 32-bit / 384kHz
- 3. Optical toslink SPDIF
- 4. HDMI IIS INPUT*
* Compatible with Mano Streamer (high res) and Pink Faun I2S stereo bridge
- ACSS single ended (Optional RCA)
- RCA single ended
The R-2R DAC has become popular and affordable. From DIY kits and completely up to of the shelf high-end products.
In the lower end DIY market, the R-2R design is often based on old technology; designed long time ago by MSB, often includes basic R2R ladder design only and not include the wonderful correction design of the modern MSB technology. Previous less good designs used data shift registers logic chips in serial mode to convert the data to an analog signal. The stubborn R2R issues cannot be avoided this way and performance is almost entirely depending on the accuracy of the ladder resistors.
In the High-End of the shelf (finished products) market, the R2R design is usually much more complex when outstanding performance is offered. A basic R2R ladder is simply not sufficient to achieve the desired sound quality. Some manufacturers are using shift registers design to realize ladder compensation. A less complex, unfortunately also a less performing design based on traditional logic chips working in serial mode.
A far better design switches resistors in parallel mode; an ultra-fast FPGA chip controls and corrects the R2R ladder. The parallel design mode controls every bit respectively and therefore achieve unprecedented performance. (In parallel mode only 1 clock cycle is needed to output all data; serial design mode needs at minimum 8 up to 24 clock cycles) The parallel design is particularly complex, however when it is done properly it can correct every bit of the ladder. (Photo below shows a FPGA design with R2R ladder). With incredible speed and accuracy the R2R 7 will correct the unavoidable imperfections of the basic R2R ladder caused by tolerance of resistors; avoid glitches at ultra-high speed to deliver unrivaled musical performance.
TOLERANCE OF RESISTORS IN LADDER
Some manufactures claim to achieve good performance becuase they use lowest tolerance ladder resistors. The following calculation example will cover this. At 16 bit the tolerance of 1/66536, 0.1% (1/1000) it is by far not enough to achieve decent performance. Even using resistors with 0.01% (1/10000) tolerance, lowest tolerance available today,cannot deliver the desired performance This is just 16 bit, imagine a 24 calculation! To process 24 bit resolution it would require resistors with a tolerance of 0.00001%. This is purely theoretical; if this tolerance would exist the discreteness of the switch logic chips will already have too much internal impedance and will shake-up such design.The tolerance of the resistor will never solve Imperfections of a ladder.
The solution lies in the correction the ladder and not only depend on the tolerance of resistors. It’s a combination of both: Ultra-low tolerance resistors controlled by a correction technology using very high speed with parallel FPGA processing.