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11th. of Dec. 2017: USB isolator
upgrade for Amanero combo
384 as default.
USB isolator improves quality
of signal coming to dac . In AB comparison , it can improve on sound
transparency slightly .
24th. Feb. 2018 : Separate pure class A PSU power
supply for Amanero upgraded.
Since the USB
isolator has been added it improved things a bit. Sound quality has
become less digital but some customers still have expressed concern
that polluted USB power from computer may still compromise sound
Now we have included separate
pure class A PSU power supply for the Amanero to boost the USB sound
quality . After the upgrade , USB connection don't use any USB
power, and now can work with not only computers but Iphone and Ipad.
had design and test based on the AP SYS-2722
(The top-drawer professional equipment in world)
The different between dual ES9038 Pro and
single ES9038 Pro is large:
difference is not only the DNR, but the dual ES9038 Pro is working
in mono mode, the channel crossing is improved and offer a larger
and more precise sound stage.
The difficulties of dual ES9038
In 2014 we have began design of the
Dual ES9018, but we had failed even though we have tried try a lot
of methods . The dual ES9018 can sometimes work fine but some times
had delay on one channel, even though the human ears may not hear
the delay but it is easy to show on the oscilloscope .
We could not sale this
The problem has been fixed:
ES9038 pro had been released more than 9 months ago. Since its
release, we developed single ES9038 but I still I was missing the
dual ES9038 Pro design just like i miss an old friend.
I solder the dual ES9038
Pro in the old development boards, I failed again.
I have given up the old
development boards but I had not given up the project.
I start design a new
board with the FPGA to separate the channel data and control the
ES9038 Pro timing .
Then, the problem has
The FPGA is
important in the NFB 7.77:
The FPGA is Programmable
FPGA had applied in a lot high end grade DACs, like the popular
ROCKNA WAVEDREAM DAC.
hardware construction can through the complex software design and
arrangement , be upgraded through the software upgrade.
Upgrade to the
firmware is the same as same as upgrade to the hardware. That design
is much more flexible . It can improve on sound quality and add the
newest functions , it can never become out of date.
What the FPGA duty
in the NFB 7.77:
1, Separate the data feed to dual
ES9038 Pro for working in mono mode.
2, Clock re-clock
process and FIFO design for all inputs , the output data can be
exactly synchronised with clock signal, to reject jitter.
3, Built in high
performance SPDIF interface , bypassing low performance SPDIF
interface of the ES9038 Pro .
Full discrete output stages:
The signal last stage is the
analog output stags , they greatly effect the whole DAC sound
The output stages working after
ES9038 pro, they are full discrete transistor built with hole parts
but not SMD parts .
The high speed ACSS amps
work as the signal gain and processing , they are of non feedback
design and working in current signal mode . the dual ES9038 pro
output [current signal] goes through the ACSS amp .
In our design output
stages working in pure class A , and without any negative feedback
for the most pure and life like sound reproduction .
There are 4 pcs OPA built
in as DC servo , so the DAC can work well without coupling caps and
output the most neutral sound.
Heavy power supplies design:
DAC had built in 3 R-core transformers, in totol of 150W of power to
supply digital sections also Left analog and Right analog section .
There are in total of 14
groups of pure class A PSUs and 3 groups linear PSUs to provide
power to different parts . All the PSUs provide ultra high speed and
ultra low noise performance.
has separated the digital, Left analog, Right analog and power
transformer parts, every part has been separated by 5MM thick
aluminium boards avoid the interference between each others.
The Left and Right analog
parts are symmetrically placed beside the digital parts , keep the
wires and distance of the same length. That helps to create more
exact sound stage.
sound quality adjustment :
people may not like the sound of ESS chips. They are consider to
sound artificial . We want to change this perception .
At first we want to let
the unit fully burn in, then adjust the parameters layout and design
to lower the distortion to absolute minimum . This is easy part..
Then we have to spend a
long time on listening tests and constantly comparing sound quality
. Than we adjust the parameters to change the Odd and even harmonics
to let the sound be life like and palpable.
At the end the DAC may
not have least amount of distortion but has the most neutral sound
with life and realism.