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Audio-GD
r2r74_173577131r2r75r2r711r2r72r2r78r2r710

Audio-GD - R2R 7 Discrete Ladder DAC (Balanced / FPGA / Amanero USB / DSD, DxD)

€ 2.749 (€ 2.272 excl VAT)
Black Edition Information
Singxer F1 USB (Replace Amanero) with installationInformation
AES/EBU Digital InputInformation
Coaxial RCA Input (Replace BNC)Information
Power cable (Default IEC EURO)
Audio-GD - Digital SPDIF coax interlink BNC (1m)Information
Audio-GD - Digital SPDIF coax interlink RCA (1m)Information
Audio-GD - ACSS Analogue balanced interlink (mini-xlr)Information
Audio-GD - Analogue RCA interlink stereo pair (1m)Information
Audio-GD - Optical Digital Toslink Cable (1M)Information
  • Description
  • Specifications

Audio-GD - R2R-7 - Discrete R2R (PCM & DSD/DxD Balanced DAC)

Balanced discrete R-2R digital analogue converter equipped with advanced high speed ladder correction including optimized FPGA FIFO buffering and re-clocking. All parts and components are selected based on excellent sonic and measurements performance. Components used are e.g. WIMA caps; DALE and Vishay resistors, KOA transistors and NOVER capacitors. The design (e.g. low noise power supplies; discrete analogue output stages) were being selected after many years of experience and practices and are considered to perform and provide finest sound quality. Up to date technology supporting high resolution including native DSD, DxD and hyper-modern inputs like Amanero USB and LVDS I2S inputs.

Unique R2R correction technology. Digital signal processing driven by high-speed FPGA supporting FIFO buffering and re-clocking. Software up-gradable design enables future new capabilities and improvements.

Enjoy DSD512 and best sound quality with Singxer F1 USB module installed (Replacing Amanero)

SPECIAL INTRODUCTION OFFER
COUPON CODE: AGDR2R7


REVIEW 6MOONS: "In conclusion, we were very impressed with this DAC. For the price, it offers very good sound which is unusually adjustable to individual hardware conditions and taste."

Blue Moon award


SUMMARY

Software up gradable design. Two high performance TCXOs to process different sampling rates 44,1kHz and 48kHz sampling range to eliminate jiter.

  • True balanced design
  • Digital DSP for optimal signal processing
  • Discrete push-pull R2R DAC design
  • Internal OCC wires & low-jitter TCXO clocks applied
  • Discrete analogue output stages
  • DC coupled design (No capacitors in signal path)
  • Non- feedback ACSS analogue output control
  • Power supply consist of 21 regulated low noise regulators
  • Over 50,000uF power capacity to purify the power supply
  • High-grade matched transistors per channel
  • USB Amanero Combo384 interface with Galvanic Isolation
  • High Res support: DSD64 - DSD512 & DxD

SOUND CHARACTERISTICS

R2R-7 is characterized by its coherent, transparent and natural sound. Striking is the spatial sound image. Rich in detail and strong authority. You'll forget that you're listening to a digital source.


USB Singxer F1 Option (Replacing Amanero)

MAGNA HIFI is offering a significant upgrade of the internal USB interface by replacing the Amanero USB interface for a more sophisticated Singxer F-1 XU208 board using the Crystek CCHD-575 ultra low phase noise clocks. Besides the sound quality improvements it enables native DSD512 support! We'll make sure the Singxer F-1 is properly installed and using internal ultra clean power source from the internal DAC to ensure best sound quality!

Black Edition

Black Edition is an unique option for Audio-GD equipment. Click here to read about our unique and special Black Edition option


INPUTS
  • 1 Coaxial RCA SPDIF
  • 2 Coaxial BNC SPDIF (Option: Replace by Coaxial RCA)
  • 3 Coaxial RCA SPDIF
  • 4 Optical Toslink
  • 5 I2S RJ45 (LVDS)
  • 6 I2S HDMI (LVDS)
  • 7 USB

OUTPUTS
  • ACSS balanced
  • XLR balanced
  • RCA single ended

 R-2R DESIGN

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.

 

agd r2r7 mh

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.

PROS AND CONS OF DISCRETE R-2R LADDER DAC

Advantages

  1. R-2R will not convert the clock signal into the output signal.
  2. R-2R is less sensitive to jitter
  3. The output signal is more accurate with R-2R

Weaknesses:

  1. Modern Sigma-Delta chips offer exceptional THD; R-2R offers satisfactory THD results. 
  2. Accuracy and glitches of the ladder resistors require complex technology to enhance 

ULTRA FAST SIGNAL PROCESSING

FPGA stands for Programmable Array Logic. Nowadays the FPGA is widely adopted in audio devices. The internal hardware design is fully controlled by complex software. A huge advantage is the fact the software in the FPGA can easily be upgraded offering new capabilities or improve the performance of the device without replacing any hardware. Flexible and future proof design.

R2R7 FPGA responsibilities:

  1. High performance SPDIF interface, replacing traditional less good performing SPDIF interface chips like DIR9001, WM8805 or AK411X,etc.
  2. Full re-clocking process with FIFO design applicable on all inputs. This way the output data keeps fully synchronized with the clock signal to reject any jitter.
  3. Built in 2X, 4X and 8X oversampling and digital filters and on top of this 4 different true NOS (only analog 6dB filtering) modes. To completely configure the sound according to your taste.

 

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 components 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. Resulting in a strikingly neutral sound.


R2R710.jpg

POWER SUPPLIES

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.


DIGITAL CONFIGURATION GUIDE
DSP configuration for Singularity Version since May 15th 2017
MODEL S2    
SINGULARITY (OS) OFF   Oversampling + DIgital filtering
NOS (Pure NOS mode) ON NON Oversampling + 6dB filtering
Bypass ON OFF I2S input only
PLL ON OFF
Dithering ON OFF
SINGULARITY (OS)      S2 = OFF
Oversampling IPS0 IPS1  
8x OFF OFF Default
4x ON OFF
2x OFF ON
1x ON ON
       
NOS (Pure NOS mode) S2 = ON
NOS MODE ATT0 ATT1
NOS 3 OFF OFF Default = OFF
NOS 2 OFF ON
NOS 1 ON OFF
NOS 3 ON ON

USB SUPPORT

Download USB Amanero drivers for Windows 10
Download USB Amanero drivers for Windows 7 & 8

No drivers required for Linux and/or Mac OS
OSX 10.6+ and Linux with UAC2 compliant kernel
Microsoft Windows: KS/Wasapi/WDM/ASIO


 

Brand URL : http://www.audio-gd.com/R2R/R2R7/R2R7EN.htm
Weight: 15 kg
Width: 430 mm
Length: 430 mm
Height: 93 mm
Brand: Audio-GDAudio-GD

Specifications

R-2R Discrete Ladder(s)
-120dB
0.0005% (20Hz-20KHz, Non-Weight)
2.5V (RCA) 5V (XLR) 2+2mA (ACSS)
0.5 Vp-p
19 dBm
USB / I2S 44.1kHz - 384kHz /32Bit & DSD64-DSD512.| Coaxial: 44.1kHz - 192kHz /24Bit Optical: 44.1kHz - 192kHz /24Bit
1.0, 1.1, 2.0 & 3.0
Windows, iOS, Linux
> 130dB
0.05dB
19
45W Version 1: 100-120V AC 50/60 Hz Version 2: 220-240V AC 50/60 Hz
W430 X L430 X H93 (MM, Fully aluminium)
USB Cable
IEC Power Cord

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