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(Dual ES9038Pro + FPGA Processor)

Discrete  DAC + Headphone amplifier / Preamplifier
Built in FPGA processor , reject the jitter
DSD , DXD support from USB &I2S
Dual 32bit / 768K Sabre ES9038Pro
32bit / 384K Asynchronous Transfer Amanero Combo 384 with USB isolator
Built in OCC and TCXO ,no upgrade options
9000mW at 40 ohm (Pure Class A, per channels )

Price:  (Exclude shipping cost,include below remote)
USD2080 (With USB Isolator and PSU upgraded)



Summarize Use Manual Specs Custom Option Shipping Cost

Click to read the Amanero combo 384

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.


Since 4th. April 2018,   the model had upgrade the volume ports:
The upgraded volume ports had built with Vishay or KOA resistors with dual resistors parallel ,  tolerance low to 0.05% .

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.

The difficult 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 product.

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 had fixed.

The FPGA is important in the NFB 27.77:

The FPGA is Programmable Array Logic.
           Nowdays the FPGA had applied in a lot high end grade DACs, like the popular ROCKNA WAVEDREAM DAC.
           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 27.77:

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 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 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 10 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 digital parts had applied the double stages PSUs power supplied .

Volume control:
           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 .
       But in the NFB-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 groups  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.
            In NFB-27 is applied a four channels digital control relays based volume control. .NFB-27 has total four channels through changing the DALE resistors to control the volume for avoid channels imbalanced ,achieve the best performance and sound quality of the gear.
           NFB-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. While users change the volume, the different relays break or close, it may had slightly switch sound on output and disappear while stop change the volume.
          Supper Exponential volume characteristic      Volume steps comparison to normal volume knob       

The overall arrangement :
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 each others.
           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 adjust :
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 finished.
         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 like real.
         Finally the DAC may had not the minimum distortion but had the most neutral sound with life and real.




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