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You had ever look for, now it had exceed the expect.
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NFB-7.77   
(Dual ES9038Pro + FPGA Processor)

Dedicated Discrete Fully Balanced DAC
Built in FPGA processor , reject the jitter 
DSD , DXD support from USB &I2S
Dual 32bit / 768K Sabre ES9038Pro
32bit / 384K Asynchronous Transfer AmaneroCombo 384 with USB isolator
 
Built in OCC and TCXO ,no upgrade options


Price:    Price:      (Exclude shipping cost)
USD1980 (With USB Isolator and PSU upgraded)

Please send your address, name to
audio-gd@vip.163.com get the quote.

 

 

   

 
Summarize Use Manual Specs Custom Option Shipping Cost

Review:  http://www.hifizine.com/2011/03/audio-gd-nfb-7-dac/
Click to read the Amanero combo 384
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11th. Dec. 2017: 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.


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The difficulties  of dual ES9038 Pro:
           In 
 2014  we began   to design 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 product.

The  problem has been  fixed:
           
The 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 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 been  fixed.

The FPGA is important in the NFB 7.77:
           
The FPGA is Programmable Array Logic. 
           Nowadays the FPGA had applied in a lot high end grade DACs, like the popular ROCKNA WAVEDREAM DAC.
           Its internal 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 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 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 .I  don't like other design with  multiple conversion to 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 without  difficulty .
           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:
           
The 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 PSUsprovide  ultra high speed and ultra low noise performance.
           

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The overall arrangement :
           
The DAC 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.


The sound quality adjustment :
           
Some people may don't 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.

  

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