Please note: The PCM1704UK can not support DSD playback. User need conversion the DSD to PCM in the source device.
Price: USD3880 ( Exclude shipping cost .)  
Please send your address, name  to audio-gd@vip.163.com get the quote.
Apply 90/98MHz Accusilicon 318B femtosecond clocks:
       

Shipped since July 2019, the unit has upgraded the transformers , can power on long term.

Click to download the driver of  Amanero combo 384

Features of HE-7 MK2:
         1. Using the latest designed discrete servo stabilized power supply to feed the digital circuits, the noise level is comparable to that of a battery, but without the dry and thin sound characteristics of it, and thus the product's operating temperature is significantly lower than that of the previous model. The clock circuit and the analog circuit are still powered by a pure class-A regulated power supply for the best sound results (New upgrade)
          2. By listening to a turntable and studying its sound for a long time, we have successfully integrated the analog vinyl sound characteristics into this product, this being allowed optionally through the front panel. (New feature)
          3. Both the USB and HDMI inputs are equipped with isolators, and two sets of linear power supplies to separately supply power to the USB and HDMI modules before the isolators to prevent interference from signal sources.
         a, USB uses a two-way transmission isolator, which not only transmits IIS signals to the FPGA processor, but also receives the synchronous clock signal sent by the FPGA processor. The USB interface itself is no longer equipped with clocks. The synchronous clock is applied to make the signal transmission more accurate and upgrade sound quality to an excellent level. The sound quality is now in fact better then with the previous generation HE7 fed by the DI-20 (not quite as good as with DI-20HE however).
        b, the HDMI module is now equipped with an independent isolator to improve the sound quality of the HDMI input.
        4. Display of the input signal sampling rate function.
        5. The 10MHz clock input allows the use of an external clock generator.
        6. The FPGA operates using the parallel data processing mode.
The IIS signal is serial data transmission. Each data bit requires one clock cycle. One frame of left and right channel data requires 64 clock cycles, so stability over a 64 clock cycles is needed.
The parallel mode only needs one clock to transmit and process the 32-bit data of the left and right channels, which greatly improves the processing speed and is less affected by the stability of the clock.
        IIS input data (USB and HDMI-IIS) is reorganized into two sets of 32-bit parallel data as soon as it is inputted.  After the SPDIF signal is demodulated, it is also sent to the next level of processing through two sets of 24-bit parallel data.
         According to listening comparisons, the parallel processing mode can make the sound clearer and more neutral, with better dynamics and a more analog flavor.
        7. The clock management design of the new architecture makes the clock work more stably, which brings higher transparency and more details.

Pure analogous Regenerative power supply :
            The regenerative power supply like a proprietary electric generator built in the unit.
             It can block most disturb from the power line , supply the ultra clean power supply for the audio amps , reproduce the most neutral and analog sound like audio signal for the system and the users.
             In the regenerative power supply design, the AC power through the regenerative input transformer , conversion to DC power ,through the class A PSUs power supply for the regenerative wave generator and driver stages .
             A balance regenerative regular wave generator produce the ultra low distortion 50Hz wave ,through the balance  gain amps and the strong  output stages , drive the regenerative transformers produce the clean AC power supply feed to the separate class A PSUs power supply for the L and R channel preamps .
            The class A parallel connection PSU has very high input impedance to avoid disturb through the PSU from affecting the signal parts and low output impedance with very fast speed and high linear,  it is a very clean power supply.
             Audio-gd on the regenerative power supply design points  :
             1, Through analyzed the AP SYS-2722 ,do a lot practises ,test and listen , full analog design of the regular wave generator have much lower distortion than the digital generator.
            2, Digital drive stages have higher efficiency , but full analog drive stages have much better analog sound like .
            3, 400Hz regenerative wave have higher efficiency , 50Hz regenerative wave had much far away the human ears sensitivity area than the 400Hz, boost the sound have much better analog sound like.



Pros and cons of PCM1704UK R-2R DAC  :
Advantages:
         1.R-2R will not convert the clock signal into the output signal.
         2. R-2R is not sensitive to jitter while Delta-Sigma DA is much more sensitive to jitter.
         3. The output signal is much more precise compared to Delta-Sigma DA .
Weaknesses:
        1.THD today is extremely good with Sigma Delta chips; R2R ladders are good too but not as good.
        2. Glitches and accuracy of the ladder resistors are very difficult to avoid and require complex technology to resolve it.

　

Importunacy of the FPGA/CPLD:
                 FPGA stands for Programmable Array Logic. 
            Nowadays the FPGA is applied in a lot high end grade DACs; like the popular ROCKNA WAVEDREAM DAC. 
            We have applied the FPGA in our DAC products since 2008.
            HE-7 has built in 1 pc FPGA and 3 pc CPLD programmable chipsets to separate the different configured circuits for avoid interrupt.
            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/CPLD tasks :
           1. The FPGA high performance SPDIF interface, replacing traditional  SPDIF interface chips like DIR9001, WM8805 or AK411X wich are lower in performance in comparison to FPGA.

           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!
         4. Simulate the tonality of vinyl disc playback through a unique design.

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:
                 4 Uses high-performance R-core transformers with a total power of 295 W and more than 70,000 uF of audio-grade filtering capacitors to ensure the purity of the power supply.
           10 sets of newly designed discrete servo stabilized power supplies and 7 sets of ultra-high-speed linear stabilized power supplies provide separate power to the digital circuit of this product.
            The 7-group stand-alone class-A parallel regulated power supply separately supplies power to the regenerative power driver and each part of the analog audio.
           All power supplies have ultra-high-speed and ultra-low noise characteristics.
           

Finishing touch:
              The HE-7 has completely separated power supplies .Digital, left and right analog channel have their own dedicated transformer. All boards and transformer compartment are separated by 5mm thick aluminum plates for high isolation degree.
               It improves the signal-to-noise ratio, isolate the harmonic interference and reduce noise, which will make the sonic background cleaner and blacker.
              The Left and Right analog parts are placed symmetric beside the digital board to keep the wires and distance identical to ensure equal output performance on both channels .
              The R2R DA modules are assembled between two aluminum boards to avoid any RF interferences.