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NFB-29.38 (ES9038Pro)

Discrete  DAC+ Headphone amplifier + Preamplifier
With 2 groups RCA  analog inputs

DSD , DXD support from USB and I2S inputs
32bit / 768K Sabre ES9038Pro
32bit / 384K Asynchronous Transfer
Xmos U208
Built in OCC

Price: (Free mini remote controller but it had not warranty,exclude shipping cost.)
NFB-29.38 : USD808 (ES9038 Pro, Amanero & TCXO built in.)
NFB-29.38 : USD743 (ES9038 Pro, Xmos U208 built in)
NFB-29.28 : USD638 (ES9028Pro & Xmos U208 built in)
Extra metal remote :  USD50 

   

  

Summarize

Use Manual

Specs

Custom Option

Shipping Cost

Audio-gd products had design and test based on the AP SYS-2722 (The top-drawer professional equipment in world)


Amanero combo 384 Intruduce and driver download
Xmos U208 Introduce and drivers download

Different between NFB-29.38 and NFB-29.28:
The different is the NFB29.38 had built in ES9038 Pro, NFB29.28 had built in ES9028 pro, other parts are exact same. In sound quality, NFB29.38 had slightly better on transparency.

Different to the NFB-28.38:
The NFB-29 is a single ended DAC with headamp and preamp (+/- 30V DC high voltage power supply ), The NFB-28 is balance DAC with headamp and preamp (+/-15V DC power supply ).  So They had same output power specs can drive most headphone as well.
If customer like to keep your headphone with single ended connector (6.3MM), choice the NFB-29H get better performance than the NFB-28.
If customer had the balance connector headphone or can modify the headphone with balance connector, choice the NFB-28.

Summarize
Multi-ply shield boards to isolation the power input socket , transformer, power supplies, digital part and the analog part .
Fully Discrete design built by discrete analog stages without any OPA and coupling caps in the signal channels, built in  DAC, output for headphone (4-pin XLR or 1/4") and   preamp  output.
Non- feedback ACSS analog output stage .
The analogy amps working under +/- 30VDC for got the super well linear and offer high power output in single ended design.
LED display avoids RF disturbance for better sound quality
Large R-core transformers and Hi-fi grade parts like DALE resistors, WIMA caps .
Total of 6-group PSUs are used to purify the power supply , the analog amp has discrete PSU power supply
Two-channel digitally controlled relay-based volume control to avoid channel imbalance and improve sound quality.
100 steps volume control , it can working fine with high and low sensitivity headphones and speakers.
4 digital inputs:   USB / I2S /Optical / Coaxial RCA
2 analog inputs:  RCA / RCA
DAC output:   RCA / RCA / ACSS  (User can set either variable output level as preamp or fixed output level as dedicated DAC )
Headphone output : 4 pin XLR / 1/4" (6.3MM) SE
4 types gain modes , drive the high and low sensitivity headphones as easy .  

 


Technology detail

Detail of the Current Conveyor Technology

Impedance matching:
             The NFB-29 had two groups analogy RCA inputs ,can connect external DACs , working as a decent headphone amp .There are a lot different DACs in worth, they had different design and output impedance . For avoid the sound quality effect by different DAC's output impedance, in the NFB-29, it had design a pair single-ended class A FET buffers in the input . All the analogy RCA input signals through these FET buffers, the output impedance had become very low, even the source had high or low output impedance.
             The FET buffers working on pure class A state, and it is so short signal journey , it can keep the sound quality without coloration ,dry and harsh .
             


 Simple and short signal transfer is best:
    
   The NFB-29 applies the newest ESS high-end Sabre32 DA chip ES9038Pro which can support up to 32Bit/384KHz input .
       
ES9038Pro in voltage output model , there is -12DB THD+N worst , to be achieve  the best performance of ES9038Pro , must work in current output model .
       In some other ES9038Pro built in DAC design , ES9038Pro output signal have to through 3 step OPAs implement analogy signal process .
       The NFB-29 had different design , applies Non-feedback ACSS design. The ES9038Pro feed to the ACSS circuit by balanced model without any OPAs .
       The ACSS circuit naturally working in current model and have design difference current input , it can transfer the ES9038Pro current signal to output and implement the I/V conversion in current model in one ACSS amp . And this ACSS amp only have one current gain stage , the ES9038Pro output signal only through one stage can arrive the output stages .
      The shortest signal journey can reproduce the best detail and dynamic, and almost without sound coloration , It can show the  real performance of the ES9038Pro .
       So our ACSS design is the best combo with ES9038Pro achieve the best performance .
          
       Upside in the picture is the standard ES9038Pro headphone amp design. The bottom is the NFB-29 design .
                                                  


      

        The ACSS also is a non-feedback technology made with fully discrete amplifiers. Most people know the global feedback design can offer better specs in test measurements, and non-feedback can't do well in test measurements but can offer better sound for the human's ears. Here is a conflict of the classic circuits.
        But the ACSS opens a new field, it can offer a least coloration sound which is more neutral with very low distortion and high linearity. So it can retain the dynamics, detail and neutral sound but not sound bright or harsh.
        The output buffers are Non-feedback. For low impedance, we applied a diamond output stage which is quite less colored than most conventional circuits.
        The DAC is without couple caps to avoid coloration. There are two OPAs built in as the DC serve  to keep the DC offset .
        The 32bit / 384K USB interface outputs a I2S signal to ES9038Pro . 
                  Super low THD  (Test by AP SYS-2722,0DBV output level)                         Flat frequency response (Test by AP SYS-2722)
                                                                                          
 

Strong diamond difference output stages:
             The NFB-29 had design a pare diamond difference output stages, every parts had exact matching before assemble so don't need any human adjustment . 
             The output stages working under + / -  30V DC power supplied, built in  two pair 15W transistors,  for offer strong drive ability , no matter drive the high and low sensitivity headphones  . The diamond different design can avoid switch distortion , it working as the class A but don't want large idle current .

             


Multi-ply   power supplies are the key of sound :

         NFB-29 applies the excellent DA chip ES9038Pro and excellent analog output stages, but these are not the only keys of the best sound. The power supply is most important. Even applying the best DA chip and the best amp, if matched to a average power supply, the total sound may still be average or sound musical but can't be neutral and detailed. That is why it is easy to find hi-end grade gears maybe without the best chips , but with plenteous dedicated DC supply circuits.
         The NFB-29 uses A total of 6 groups  PSU power supply for all digital and analog circuits.
         To achieve high S/N, the control circuit is powered with separate regulator.


 
               Strong power supply.
       
        

 The I/V conversion volume control without sound degradation:

           Usually the volume control can be implemented in the DAC + amplifier combo in two methods
           Method 1: The volume control is implemented into the digital stage. The major drawback is that 1 bit of the D/A conversion is lost in every 6DB volume reduction. So, even though the built-in DA chip is 32 bit, in fact, only 16 bit may be left at low volume level.
           Method 2: The volume control is implemented in the analog amplifier input stage through a volume pot to reduce the signal level. However, the volume pot affects the sound quality adversely. A low grade volume pot loses the details and creates channels imbalance resulting into soundstage distortion. Even a high grade volume pot inevitably loses the details. Both methods degrade the sound quality.
           The NFB-29 applies the I/V conversion volume control, the volume control is just a variable passive I/V conversion being placed at the ACSS amplifier output, where the output is current signal but not voltage signal. I/V conversion is to change the volume level from the current (I) signal to the voltage (V) signal. (Like R-2R D/A chips output passive I/V conversion) It can keep the signal frequency band flat while not losing any detail. It does not degrade the sound quality in every volume level. In front of the volume control, there are four groups of diamond non-feedback buffer output stages that offer very low output impedance.
            Mark Levinson also knows that current volume control has great benefits, so in the volume control of his top grade hi-end preamplifier No.32, he uses many components to change the voltage (V) signal to current signal (I), then through the R-2R network to control the volume, and finally changes back to voltage signal (V) again. NFB-29 simply works in current (I) signal domain, and technically, it is superior to the conventional technology due to less conversion.
            NFB-29 applies digitally controlled relay-based volume control in 100 steps. It has 90DB control range ( most other volume control only had around 70DB range, so the device want to design the gain switches ) allow users to control the volume level smoothly. NFB-29 has two relay-based volume control  channels through changing the DALE resistors to control the volume to avoid channel imbalance, achieving the best performance and sound quality of the gear. While change the volume, the combine relays break or close, it may had slightly switch sound on output and disappear while stop change the volume.

        Precise  digitally controlled relay-based volume control.            Fast / Slow two volume control characteristic

                                                         

The Multi-ply shield boards  for avoid the interrupt:

           The NFB-29 had built in Multi-ply shield boards, to separate the  transformer, power supply, digital parts and analogy parts for avoid the different parts had disturb . Even though the power input IEC socket, it had hide in a copper shield box .

     
Static storage mode control software:
           In most control softwares design, the MCU will continuously output data to the perform parts , the MCU had the very high speed, so the output data become high frequency impulses disturb the audio signal circuits make the sound worst .
This product had applied static storage mode control software , the MCU output once control data and save in the perform parts while just power on and users operate ,then stop output data until users next operation. This design make the sound quality improve on the clear and transparency .

Components:
           Uses all Hi-end grade components, including DALE resistors, WIMA caps, custom order NOVER (UK brand) caps, Neutrik headphone output socket, ect .


 

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