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audio-gd DAC Head Amp Pre Amp Power Amp DIY Kits Cables
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NFB-8
Dual WM8741 inside
ACSS/XRL/RCA output balanced DAC
AES / Coaxial / BNC / Optical / USB input
Supports up to 24Bit/192KHz

Price: USD1200  (Exclude shipping cost)
Weight: Approximately 15kg
Dimension:  W430 X L430 X H85(MM)
Accessories: Stock power cable X1,stock optical cable X1,USB cable X1

Summarize: Fully discrete amp without any OPA , couple caps ,non- feedback analog output stage and non-feedback Class A power supplys .
       Uses three R-core transformers (135W total), one 35W R-core supplies power for digital parts, another two 50W R-cores supplies power for analogy parts. The power transformers and rectifiers are carefully shielded from the electric field of the power transformers and rectifiers' frequency transmission. More than 45,000uf audio grade NOVER capacitors are used to ensure ample and smooth power feed. The NOVER capacitors are specially custom order from NOVER (U.K.) according to Audio GDs requirement. A total of 16 PSU groups are used to purify the power supply. To achieve Silent operation, the control circuit is powered with separate regulator.
       Uses mostly DALE and Vishay resistors,  WIMA ,EVOX capacitors and a lot SOLEN caps. The electrolyte capacitors are custom ordered from NOVER (a UK brand), Sanyo OS caps, and exact-matched transistors. RCA sockets are custom ordered and 24k gold-plated. All transistors are Toshiba and Hitachi.

Sound Characteristics:  "Neutral but smoothness sounding ,it doesn't sound skeletal or digital (or metallic). There's meat aplenty on them bones . It's a sigma-delta DAC chip implementation without the dryness, neutrality without the emotional disconnection" - John Darko

Feedback :

http://www.head-fi.org/t/529882/new-audio-gd-nfb-8-wm/105#post_7711879

What's different between these popular chips
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@ Dual WM8741 ES9018 AD1955 AD1852 WM8740
SNR 128 DB (Mono) 120 DB 120DB 114DB 117DB
DYNAMIC RANGE 128 DB (Mono) 129 DB 120DB 114DB 117DB
    
                                                                 
                                                                              

                                                                

About ACSS:
         ACSS (Audio-gd Current Signal System) is Audio-gd's system for transmitting audio signals in the current domain. This concept, first seen in 1966, we have used for many years, and since 2006, have evolved the technology to include all audio signals in our systems from the digital source to the power amplifier. Since 2005, ACSS comp5nts have become Audio-gd's most popular products.

What's different between Diamond Differential amp and the Diamond buffer ?

            
I read on forum, some people maybe confounded the diamond Differential amp and the Diamond buffer . See the circuits of below please.
          
Diamond Differential amp                                       Diamond buffer
                                                    

 
                 In NFB-8, it is applied the ACSS + dual FET buffer output stages, which is the neutral design. But the WM8805+WM8741 sound a bit smooth so total sound tone is smooth too.
                                
 ACSS + dual FET buffer output stages
                             


About NFB-8
         NFB means Non-Feedback.
        The NFB-8 version applies the newest  high-end dual WM8741 which can support up to 24Bit/192KHz input (AES , Coaxial and optical input support up to 192KHz ,  USB support up to 96KHz/24bit). Similar to other WM8741 designs, Our NFB-8 version applies Non-feedback ACSS output stage. The dual WM8741 feed to the ACSS output stage without any OPAs so it can avoid sound coloration .
        The ACSS 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 the dual FET buffer output stage which is quite less colored than most conventional circuits.
        The DAC is without couple caps to avoid coloration.
        The 24/96 USB interface outputs a I2S signal to dual WM8741.
        Applied the WM8805 as the SPDIF interface , its sound characteristic is same with the WM8741 which is detail but smooth, and it can support up to 192KHz input.  The WM8805 had quite low jitter (50PS),much less than the CS8416 ( 200PS ).
        Real fully balanced discrete design.


      

 
Click image to enlarge.         
        

         NFB-8 applies the excellent dual DA chip WM8741 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 normal 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 or amp stages, but with plenteous dedicated DC supply circuits.
         The NFB-8 uses 15 groups of high-quality class A parallel connection PSU with dedicated DC supply double-stage PSU, which can offer very clear DC power for the DAC, producing a very black background and neutral sound characteristic. The double-stage PSU is very important for digital parts. Some designs may have very low jitter in theory, but if the power is supplied by a dirty or low-speed power supply, it will increase the jitter and pollute the data, and degrade the sound quality obviously.
        The class A parallel connection PSU has very high input impedance to avoid pulse through the PSU from affecting the DAC and low output impedance with very fast speed and high linearity, so it is a very clean power supply. In my experience, its sound is better than battery power supply, better human sound and neutral.


  
             

 

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If I only use the RCA output, is the NFB-8 wasted or not fully utilized?
    The NFB-8 is a real balanced output DAC, it has XLR (balanced), RCA (single-ended), and ACSS output. There are 4 ACSS modules in the NFB-8 for balanced output, and all the ACSS modules have balanced input, so even through RCA output, the dual WM8741 DA chips will perform fully.

Choice of power cable appropriate for your country:     When you place the order , please let us know the type of power cable you require.

NFB-8 Specs

mprovement may result in changes in specifications and
design without notice.

RCA Output
S/N Ratio:>119db
Output Level:2.56V

Frequency Breadth:20-20KHz



XLR Output
S/N Ratio:>122db
Output Level:5.12V
Frequency Breadth:20-20KHz

ACSS Output
S/N Ratio:>127db
Output:2.0MA

Frequency Breadth:20-20KHz


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