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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
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About NFB-1
NFB means Non-Feedback.
The NFB-1 version applies the
newest high-end dual WM8741 which can support up to
24Bit/192KHz input (Coaxial and optical input support up to 192KHz , USB support up to
96KHz/24bit). Similar to other WM8741 designs, Our NFB-1 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-1
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-1 uses 5 groups of high-quality class A parallel connection PSU
with dedicated DC
supply.
Two
groups of +15V and -15V for the ACSS analog output stages, two groups
of +3.3V and +5V for the
WM8741 , and one +5V for the coaxial and optical
receivers.
The
class A parallel connection PSU has very high input impedance for avoid pulse through the PSU from affecting the DAC and low
output impedance with very fast speed and high linear , so it is a very clean
power supply. In my experience, its sound is better than battery power
supply, better human sound and neutral.
If we only use the RCA output, is the NFB-1 wasted or not
fully utilized?
The
NFB-1 is a real balanced output DAC, it has XLR (balanced), RCA
(single-ended), and ACSS output. There are 4 ACSS modules in the NFB-1
for balanced output, and all the ACSS modules have balanced input, so even
through RCA output, the dual WM8741 chips will perform fully.
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Choice of
power cable appropriate for your country:
When you place the order
, please let us know the type of power cable you require.
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NFB-1 Specs
mprovement may result in changes in
specifications and
design without notice.
RCA
Output
S/N Ratio:>113db
Output Level:2.56V
Frequency Breadth:20-20KHz
XLR Output
S/N Ratio:>116db
Output Level:5.12V
Frequency Breadth:20-20KHz
ACSS Output
S/N Ratio:>120db
Output:2MA
Frequency Breadth:20-20KHz
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