About the products details, we carefully tell you: these specifics produced by AliExpress system, some of these aren't fully correct, even it is wrong. So the correct products information is derived from the detailed description. Usually the description has a few pictures and introduction. If you are in 110V area, please tell us. About the international shipping/transportation cost, it isn't accuracy on some countries, if it is expensive, please contact us! Sometimes we can find a cheap way, we must 100% reply to you! Please carefully check the packing/box/parcel when the your receiving the parcel. 

R-7HE

(Regenerative power supply)
　

Fully Discrete R-2R Resistor Ladders DAC

Fully Discrete DSD Native decoder

Fully Discrete Real Balance  Current Transmit Design

All Digital Settings By Buttons On Front Plate (Don't want open the chasis).

4 type different algorithm NOS modes, and 3 types different oversampling modes,

have 7 type different sound features,  Can be selection by the buttons on front plate.

Firmware update port assemble on rear, update the firmware without open the unit.

Built in 4 groups DA-7 V2 modules

Built in FPGA processor , reject the jitter 
DSD , DXD support from USB / HDMI
32bit / 384K Asynchronous Transfer Amanero Combo 384 with USB isolator and separate PSU power supply 
Built in OCC , TCXOs and Hi-End parts ,no upgrade options

Price:  
USD3499 (Femtosecond Accusilicon *2 and Femtosecond Crystek *2  on USB interface,USB isolator and separate class A power supply for USB interface)

Accusilicon clocks:
        
Crystek clocks:

DA7 V2 released

        In the High-End of the shelf (finished products) market, the R2R design is much more complex only to reach best performance. A basic R2R ladder is simply not sufficient enough to achieve good performance and sound quality! Some manufacturers are using shift registers design. A less complex and less performing design based on traditional logic chips working in serial mode to correct the ladder.

         A far better design switches resistors in parallel mode. An ultra-fast FPGA 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 much more complicated. Once designed properly it can correct every bit of the ladder.  Photo below shows a design with such FPGA,  can correct the unavoidable imperfections of the R2R ladder caused by tolerance of resistors, glitches to achieve best performance.

Accuracy of the ladder resistors (tolerance):

Importunacy of the FPGA in the R-7HE:

             FPGA stands for Programmable Array Logic. 

            Nowadays the FPGA is applied in a lot high end grade DACs; like the popular ROCKNA WAVEDREAM DAC. 

            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 features or improve the performance. Such design is much flexible and future proof!

 

FPGA tasks in the R-7HE

                The FPGA in the R-7HE  is responsible for:

           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 it to your liking!

 

Fully discrete output stages

               The signal last stage is the analog output stages, they can much effect the whole DAC 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. The high speed special ACSS output stages are non-feedback and current driven design. 

          Special because almost all other designs need to convert the signal multiple times from and to current or voltage, resulting in less detail and less good staging. 

          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 design without any (negative) feedback to achieve purest and a real live sound reproduction.

          The 4 OPA opamp’s are functioning as DC servo, this way no coupling-capacitors are needed and DC output is automatically biased! Resulting in a perfectly neutral sound. 

          There are no relays or other switches in the signal path after DA modules to perform the best and purest sound quality.

 

Heavy power supplies design:

             Uses four R-core transformers (In total 295W ) and more than 95,000uf audio grade NOVER capacitors are used to ensure ample and smooth power delivery. 

16 groups discrete class A PSUs power supply for the regenerative drivers and the digital / analog audio signal parts.

            This results in ultra-high speed and ultra-low noise performance. Clean and independent power for all different parts to achieve highest quality.

     

S/N Ratio	>120DB
Output impedance	<5 ohm (XLR ,RCA)
Output Level	2.5V (RCA) 5V (XLR) 2+2MA (ACSS)
Frequency Response	20Hz - 20KHz
THD
Input Sensitivity	0.5 Vp-p ( 75 Ohms, Coaxial ) 19 dBm (Optical) USB1.0 - USB3.0
Support Operate Systems (USB)	Windows, OSX, Linux, ISO
Support Sampling	USB / I2S mode: 44.1kHz - 384kHz /32Bit USB / I2S mode:DSD native 64-512  Coaxial mode: 44.1kHz - 192kHz /24Bit Optical mode: 44.1kHz - 192kHz /24Bit
Power Requirement	Version 1: 100-120V  AC 50/60 Hz Version 2:  220-240V  AC 50/60 Hz
Power Consumption	73W
Package Weight	Approximately 19KG
Dimensions	W430 X L450 X H125 (MM, Fully aluminium )