Please note: The PCM1704UK can not support DSD playback. User need
conversion the DSD to PCM in the source device.
( Exclude shipping cost .)
Please send your address, name to
get the quote.
Accusilicon 318B femtosecond clocks:
Shipped since July 2019, the unit has upgraded the transformers ,
can power on long term.
Click to download the
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.
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
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
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
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.
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.
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.
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
Pros and cons of
PCM1704UK R-2R DAC :
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 .
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:
stands for Programmable Array Logic.
Nowadays the FPGA is applied in a lot high end grade
DACs; like the popular ROCKNA WAVEDREAM DAC.
applied the FPGA in our DAC products since 2008.
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
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
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
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
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:
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.
stand-alone class-A parallel regulated power supply separately
supplies power to the regenerative power driver and each part of the
All power supplies
have ultra-high-speed and ultra-low noise characteristics.
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.