For sale is my AudioGD NFB2 purchased new as original unit no filters. I ordered unit with gold IEC outlet and extra DIR9001 coaxaI input so comes with both WM8805 and DIR9001 coax inputs. I also purchased and installed the new USB32 module which comes on current release model. Very nice sonic upgrade and highly recommend if your unit doesn't have one. USB32 also came with extra flash chips. Comes with DIR9001 installed. Low hours and smoke free. Unit is in very good condition, no scratches. Ships in original box with all cables that came with unit.
Only selling because I upgraded to a much more expensive DAC. Price $260 plus shipping to US only. Please cover paypal fee.http://www.audio-gd.com/Pro/dac/NFB22014/NFB2.33EN.htm About NFB?
NFB mean Non-Feedback .
The NFB-2(2014) applies two pcs newest Wolfson high-end DA chip WM8741 which can support up to 24Bit/192KHz input ( Coaxial and USB). Compared to other WM8741 designs, Our NFB-2(2014) applies Non-feedback ACSS output stages .
The ACSS is a non-feedback technology made with 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.
In most design, the WM8741 feed to a difference voltage amp through voltage signal . In NFB-2(2014) , the dual WM8741 has feed to the ACSS parts direct through balanced current signal . The current signal mode can bring the best signal of the DA chips .
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 output impedance is only 10 ohms.
The two OPAs in the NFB-2(2014) just for DC serve to keep the output DC offset at zero , allow the DAC analog parts are without couple caps to avoid coloration.
The 32bit/ 192KHz 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 ). Users can choice the DIR9001 module as the SPDIF interface instead WM8805, the replace is so easy without solder , only pull off and push into .
(Note: While users want to replace the DIR module, please power off the NFB-2(2014) and pull off the power cable at first )
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