there are a few jumpers in the digital part?
DAC NFB-7.1 has a few jumpers in the digital part, some customers may
believe this is a wrong design. But I definitely say no. The NFB-7.1
is designed to separate the digital ground and the analog ground,
some design will used a inductance to connect these two grounds, but
I think the inductance has a specific frequency characteristic which
is not good for audio equipment. In our design, we applied a 0 ohm
jumper to connect these two grounds, even though the jumper has 0
ohm, in the high frequencies it still has impedance to insulate the
effects between digital and analog ground.
is the third edition design:
A lot of customers recommended ES9018 to me one year ago, during
this year I made a lot of practice, at Jul. 2009, I finished the
first edition and spend lot months to test and audition. At Mar.
2010 , The second edition finished. The regular edition finished at
Click image to enlarge.
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
NFB mean Non-Feedback .
The NFB-7.1 applies the newest ESS high-end Sabre32 DA chip ES9018 which can support up to
32Bit/96KHz input . Compared to other ES9018 designs, Our NFB-7.1 applies
Non-feedback ACSS output stage for I/V conversion, and Non-feedback
power supply for the whole gear.
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.
The output buffers are
Non-feedback, for low impedance, we applied a two-stage parallel
connection, the output impedance is only 20 ohms.
Click image to enlarge.
NFB-7.1 applies the excellent DA chip ES9018 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-7.1 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,
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.
Digital & Analog / Left & Right Completely Separated Internal
Layout, from power transformer and rectifiers etc, the radiating
interferences are carefully shielded. And applied
fully mono design can reduce the channels cross , which can
reproduce a wider and deeper sound stage.
If I only use the RCA output, is the
NFB-7.1 wasted or not
NFB-7.1 is a real balanced output DAC, it has XLR (balanced), RCA
(single-ended), and ACSS output. There are 4 ACSS modules in the NFB-7.1
for balanced output, and all the ACSS modules have balanced input, so even
through RCA output, the ES9018 DA chip will perform fully.
mprovement may result in changes in
design without notice.