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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.
Dual ESS9028 Pro, working under mono mode, its DNR had 3DB better
than single ES9038 Pro .
The FPGA is important in the D-27:
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functions , and it can never become out of date.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 D-27:
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 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 pure class A design , built with 4 pcs 150W (in total 600W )
on every channels, to drive the most headphones with difficult .
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 has 3 high quality low noise,
low flux leakage, R-cores transformers.
In total 130W
power to supply all digital parts and the left and right analog
parts DC power is distributed by 15 ultra high speed low noise PSUs,
they are group became the
double stages PSUs .
parts DC power is distributed by 4 groups PSUs ..All are pure class A low noise regulated power.
in ultra-high speed and ultra-low noise performance. Clean and
independent power for all different parts to achieve highest
The volume control is also different from conventional
technology. Conventional volume control technology is
the volume control implement in the analog amp
input stage through a volume pot to reduce the signal . The
volume pots quality effect the sound quality direct , the low
quality volume pot cause lost the detail and channels imbalance
cause the soundstage distortion . Even the high
performance volume pot still cause the detail lose. Whatever
quality volume pots, must cause the S/N worst .
the D-27 , we applied the I/V conversion volume control ,
the volume control just a
variable passive I/V conversion place at the ACSS amp output ,
where the output is the current signal, not the voltage signal. The
volume control is I/V conversion, and the volume depends on the
current (I) conversion to the voltage (V). (Like R-2R D/A chips
output passive I/V conversion)
It can keep the signal frequency band flat and
not lost any detail.
It can't degrade on sound
quality in every volume level . After the volume , there are four
diamond non-feedback buffer output stages offer the
very low output impedance .
The volume control quality is much important in the real balance
gear . It must guarantee the four channels signal control exact to
achieve the performance of the real balance gear . If the cool
and hot of the balance signal can't guarantee exact, the balance
output will has large distortion cause the sound quality and
performance even much worst than a single end gear waste the
balance gear design and the cost.
is applied a four channels digital control relays based volume
control. .D-27 has total four channels through changing the
Vishay resistors to control the volume for avoid channels
imbalanced ,achieve the best performance and sound quality of
D-27 have 100
steps volume control, control range achieve 90DB (usually the
steps volume ports, potentiometer volume port, relays base
volume control all have around 70DB range ), very smooth
control range on first 50 steps , cooperate with 13DB high gain,
so can very
easy adjust the volume for both high / low sensitivity
headphone and speakers.
change the volume, the different relays break or close, it may had
slightly switch sound on output and disappear while stop change the
Exponential volume characteristic
Volume steps comparison to normal volume knob
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