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USB isolator upgrade for Amanero combo 384 as default configure.
USB isolator can avoid the computer electric interrupt feed in the
DAC cause the sound quality worse . In AB compare , it can
improve on sound transparency slightly .
24th. Feb. 2018 : Separate pure class A PSU
power supply for Amanero upgraded.
Since the USB isolator
upgraded, the Amanero had to power supplied with USB power , it make
the sound improved ,less digital but some customers have concerned
the unclean USB power may degrade on sound quality.
Now the product had include the
separate pure class A PSU power supply for the Amanero to boost the
USB connect sound quality better . After the upgraded, the USB
connect don't spend any USB power, and can working with not only
computers but Iphone and Ipad.
Audio-gd products 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:
The different not only the DNR, but the
dual ES9038 Pro working under mono mode, the channel crossing is
improve and offer a larger and exact sound stage.
problem of dual ES9038 Pro:
Since 2014 year, we had start to design
the Dual ES9018, we had fail even though try a lot methods . The
dual ES9018 some time can working fine but some time had the delay
on one channel, even the human ears may can not hear the delay but
it is easy can show on the oscilloscope .
We can't sale this
The problem had fixed:
The ES9038 pro had release more than 9
months, since it release, we are not only develop the single ES9038,
I still miss the dual ES9038 Pro design just like miss a old friend.
But solder the dual
ES9038 Pro in the old develop boards, I am fail again.
I give up the old
develop boards but I had not give up the project.
I start design a
new board with the FPGA to separate the channel data and control the
ES9038 Pro working timing .
Then, the problem
The FPGA is important in the NFB 7.77:
The FPGA is Programmable Array Logic.
Nowdays the FPGA
had applied in a lot high end grade DACs, like the popular ROCKNA
Its inside hardware
construction can through the complex software to design and arrange,
and it can upgrade through the software upgrade.
While upgrade the
firmware, just same as upgrade the hardware. The design is much
flexibility , can improve on sound quality , addition the newest
functions , and it can never become out of date.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, let them working in mono mode.
2, Clock re-clock
process and FIFO design for
all inputs , the output data can exact synchronization with clock
signal, reject jitter.
3, Built in high
performance SPDIF interface , give up the built in low performance
SPDIF interface of the ES9038 Pro .
Full discrete output stages:
The signal last stage is the analog output
stages, they can much effect the whole DAC sound quality.
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 as the signal gain and process, they are non feedback design
and working with current signal , so the dual ES9038 pro output
current signal can through the ACSS amp , don't like others design
want to multiple conversion the signal between current and voltage.
The output buffers
are the single ended FET design and two stages parallel for the low
In total the output
stages are working in pure class A state, and without any negative
feedback for the most pure and real like sound reproduce.
There are 4 pcs OPA
built in as DC serve , so the DAC can working well without couple
caps and output the most neutral sound.
Heavy power supplies design:
The DAC had built in 3 units R-cores
transformer, in totol 150W power for supply digital part, Left
analog part and Right analog part .
There are in total
14 groups pure class A PSUs and 3 groups linear PSUs for power
supply to different parts . All the PSUs had ultra high speed and
ultra low noise performance.
The DAC had separate the digital, Left
analog, Right analog and power transformers parts, every parts had
separate by 5MM thick aluminum boards for avoid the interrupt of
The Left and Right
analog parts had symmetric place beside the digital parts , keep the
wires and distance in same , made the sound stage is better exact .
The sound quality
Some people may don't like the sound of
ESS chips. They are consider the sound is like fake . We want to
change this concept .
At first we want to
let the unit had full burn in, then adjust the parameter , layout
and design to boost the distortion in minimum . This is easy
Then we had to spend a long
term to listen and compare the sound , adjust the parameters to
change the Odd and even numbers distortion to let the sound life and
Finally the DAC may had not the
minimum distortion but had the most neutral sound with life and