Please note :
DAC-19.20 built in PCM1704UK, it can not support DSD native.
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The DAC-19 is our longest life products .
We have released the first generation DAC-19 in 2005, DAC-19SE
in 2006, DAC-19MK3 in 2008, DAC-19DSP in 2010, DAC-19 (11
Anniversary edition ) in 2016 .
Since 2010, TI want to discontinued the PCM1704 chips , cause
the price quite expensive , even sale USD150 / pc in market.
The DAC-19.20 is the best design of DAC19 series, and it is the
because the PCM1704 cost is expensive and impossible buy nowdays .
It had a lot improved than
the older models.
1, Its all parts had assemble on board made the sound more neutral
and less coloration . ( except the USB module , the USB chip may
upgrade every 3-5 years , so the module design allow users can
easy upgrade in future if had the higher performance USB chip
release ) .
stronger FPGA hardware apply (same as the R 7) had offer
the best digital process performance , reproduce the best detail,
dynamic sound but still analog .
3, The all signal parts had power supply by the class A PSUs .
4, In all older model
DAC19s that the SPDIF input applied the DIR9001 which limit the
input sampling can not over 96K and limit the sound quality . In
DAC19.20 model the SPDIF input decoder has built in the FPGA , it
can support up to 192K input with better sound quality, and it is
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 .
Non- feedback ACSS analog output stage
R-core transformers and Hi-fi grade parts like DALE resistors, WIMA
caps and OCC wires .
A total of 5 groups class A parallel mode PSU power supply for all
digital and analog circuits.
4 digital inputs: USB / Optical / Coaxial / HDMI
Support up to 384K / 32 BIT through USB and HDMI-IIS
DAC output: RCA / ACSS
Detail of the Current Conveyor Technology
Simple and short signal transfer is best:
DAC-19.20 is a fully discrete design. Applies the 2
Pieces Expensive high-end grade PCM1704UK which can support up to 32 Bit /
USB / I2S input . The SPDIF input support up to 192K / 24 BIT.
Different to other PCM1704UK designs , we applied Non-feedback ACSS
analog stages. The PCM1704UK feed to the ACSS analog
stages without any OPAs and couple caps so it can avoid sound coloration .
The ACSS is a non-feedback
technology made with fully discrete amplifiers. Most people know the
feedback design can offer better specs in test measurements, and
classic 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 ACSS circuit naturally working in
current model and have design current input , it can
transfer the PCM1704UK 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 PCM1704UK 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 PCM1704UK .
The output buffers are
Non-feedback class A FET (Apply K170 which is expensive in market nowdays) design. The output impedance only had 10 ohm .
The 2 OPA opamp’s are functioning as DC servo, this way no
coupling-capacitors are needed and DC output is automatically
biased! Resulting in a perfectly neutral sound.
There are no relays or other switches in the signal path after DA
modules to perform the best and purest sound quality.
Importunacy of the FPGA :
FPGA stands for Programmable
Nowadays the FPGA is applied
in a lot of high end DACs; like the popular ROCKNA WAVEDREAM DAC.
The internal hardware design is fully controlled by complex
software. A huge advantage is the fact that the software in the FPGA
can easily be upgraded offering new features or improve the
performance. Such design is much more flexible and future proof!
The FPGA is responsible
1. High performance SPDIF interface, replacing traditional less good
performing SPDIF interface chips like DIR9001, WM8805 or AK411X,etc.
2. Full re-clocking process with FIFO design applicable on all
inputs. This way the output data keeps fully synchronized with the
clock signal to reject any jitter.
3. Built in 2X, 4X and 8X oversampling and digital filters and on
top of this 4 different true NOS (only analog 6dB filtering) modes.
To completely configure it to your liking!
Heavy power supplies design:
DAC-19.20 applies the excellent 2 pcs PCM1704UK
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.
5 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.
Diagram of the Class A PSUs for analogy parts Diagram of the
Class A PSUs for digital parts
Built in Hi-End grade parts :
have built in most high end grade parts, like the DALE resistors
(USA), WIMA caps (Germany) and NOVER parts (UK) .
These parts have through long
term practices and consider have least sound coloration .
Built in high end grade parts
have not warranty have the good sound , but the best
technology design with high end grade parts can have the high ended
sound quality .