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DSC1 v2.5, v2.6 and new versions - The pure DSD converter
Nov 2017
On diyaudio.com the official GB for DSD DAC Signalyst DSCv2 has been closed but now are available all files to produce this module for self-production on Google drive. You can use this information completely freely. |
INTRODUCTION
The high resolution PCM at 96-192KHz 24bit offer the
possibility to have a good quality digital signal near to the analog
exceeding the big limits of the CD payer.
The
DSD
is very different from PCM, using a sampling frequency 64 times higher
than that of a standard Compact Disc, offers a frequency response of up to
100 kHz and a dynamic range of up to 120 dB across the entire audible
range.
The
DSD on paper should be better than hi-resolution pcm like the 192KHz 24bit because the two
conversions (from and to the analog) are more simple (see
this article from Korg website) but the
AES Convention Paper 6086 and AES Convention
Paper 5395, seems to
contradict this.
The
DSD signal can be directly used to reconstruct the original analog signal
with a simple RC filter
but with this method we get many digital noise also using a good digital and
analog filters so forget this method.
I have lost many time and money
to test these solution, using different USB to DSD interfaces, I2S
isolators and D-type flip-flop to create differential outptus like
this by
Hazard.
The little
Lampizator and
RT audiodesign companies has
succeeded to reduce the noise and produce a DSD DAC with this method but
with some limits.
This project is based on the DSC1 that is an Open Hardware, "discrete"
delta-sigma D/A-converter developped by
Signalyst able to convert the DSD
signal to analog without noise.
This DSD converter does
not work with PCM signal so to play any audio track it is necesary
convert in DSD on the fly during playing.
There are many
opinion about the PCM to DSD conversion and I am convinced of validity,
here some measurements
about using different output.
Some
here also some open discussions on this argument:
RESULT
In my sonic performance tests I
always search to be sure of an objective result using many persons, more
systems and different environment.
This mean that the result here is
not my personal and it is not subjective like many other test published
online.
All the tests performed have demonstrated the validity
of this converter, it is much better than Sabre ES9018.
The details
are of the highest level, there is no fatigue during listening and the
scenic reconstruction is amazing.
The only disadvantages are the DSD
conversion on the fly that forces us to use computers with adequate
performance and the necessity for a passive volume regulation after the
dac becasue only HQPlayer can attenuate the level on DSD tracks.
There
is the possibility of use the AK4137 chip for the PCM to DSD convertion so
the player in this case must not be configured and the result is very
good.
HARDWARE
The DSC1 is an Open Hardware, "discrete"
delta-sigma D/A-converter developped by
Signalyst able to convert the DSD
signal to analog without noise.
This method allow to create a very simple DAC
without a DAC chip with sonic performance much better than hi-end DACs.
At this time
probably there is no commercial product using this method to convert
the digital signal to analog.
Obviously the project evolved in the differential
version called DSC2 and this is available as the
previous on some Chinese online store.
The 74AHCT595 are high-speed Si-gate
CMOS devices used for the serial-to-parallel data conversion.
Here we have a
new differential
version designed by Pavel Pogodin
with the output transformers to filter and to convert the output in
un-balanced and balanced signal.
This new module use a modified mute
circuit to eliminate any click in the transition from one track to
another using the TS5A3167, two regulated power supply using the
TPS7A4700 and a optimized signal path.
In order to reduce
output impedance to 250ohm the 4 x 32 resistors are here 8Kohm (Sumiko
RG with
tollerance 0.1%) instead of the original 15Kohm.
This module need a DC
power supply in the range 7V to10V and it is not necessary to be
stabilised but with LowESR capacitors.
The USB interface used
is the Amanero with the normal
firmware to support Native DSD.
The output trasformers has been selected by
Pavel Pogodin after many test and
also I have compared these with other models with much higher cost.
These
have a turn ratio of 2:1+1, made with a permalloy core with a thickness of
0.16mm and a declared frequency response of 10Hz a 195 KHz-0.2dB.
Now
Pavel Pogodin encouraged by my
positive feedback is developping a new optimized module to produce in a little
series.
So now I need to wait some weeks to test it and after will be
possible buy this.
Here the more compact 2.6 version
Here the new 2.5.2 in stacked configuration.
Here the new 2.6.2
FIRMWARE
It is necessary set the Amanero module with the last firmware 1099c with DSD Native support.
1) Download the update_tools oem tool 117 and Unzip in a folder, for example on Desktop.
3) When you replug the erased device, Windows can ask about a driver.
4) Be sure to be connected to internet.
5) Run ConfigOEM117.exe and select the firmware 1099c after press Flash CPU.
6) Replug the USB cable and if it's all ok the audio driver needs to detect the
device.
SOFTWARE
This hardware is compatible only with DSD signal so
to play PCM tracks is necessary a software with the on the fly convertion.
Here follows some player with this feature in order of sound performances.
HQPlayer by Signalyst available for Windows, Mac OS and Linux at a cost of 145,18 euro
Daphile Audiophile Music Server for x86 hardware, it is free and it sound near to HQPlayer but volume does not work with DSD setting enabled
AK4137 this is not a software but a chip with the function of digital sample rate converter
JRiver Media Center available for Windows and Mac OS at a cost of $49.98 + ASIO Proxy freeware, volume does not work for DSD tracks
Foobar2000 + some modules freeware + ASIO Proxy freeware
All these software need a good PC for the PCM to DSD convertion so use an Intel® Core™ i3 Processor with 2.5GHz min. and a 4Gb RAM min.
HQPlayer
This software have many algoritm and noise filters which allow many sound
variations.
At this time only with HQPlayer is possible use the volume
control for both PCM and DSD tracks and increase the volume of some dB.
Follows the screenshots to follow to enable the PCM to DSD convertion and keep
the volume control always active.
Here the task manager on my Intel i5-5300M CPU @ 2.30GHz.
Daphile
This software is an operating system based on a Linux
kernel optimized to create a music server and it is configurable with a web interface.
It run on 32bit or 64bit x86 hardware so any normal PC is good but this
must be dedicated to this use only.
The web interface is compatibe with Apple
and Android Squeezer applications available on Play store.
Both wired and wireless are supported (if these are compatible) and it can even
operate in a standalone mode where it provides a wireless access point for the
control device.
The volume control will be disabled if you select on audio
interface panel the PCM to DSD convertion.
Follows the guide for the
installation and configuration
of Daphile for high-quality conversion of PCM to DSD.
1. Download from x64 version with real-time kernel support. Or the latest beta version.
2. In the BIOS of the computer, be sure to disable all built-in audio devices.
So Daphile will work only with Amanero in UAC2 mode and it
will not use the extra ALSA layer.
http://www.modelpromo.nl/Audio-Dandy_streamer_Daphile.htm
3. It is desirable to disable Hyper-threading support for the CPU in BIOS.
4. Write the Daphile image on a USB flash drive with any available software like
Win32DiskImage
or Rufus.
5. Switch-on the target PC
with USB flash drive inserted and select in the bias the boot from USB.
6.
During the Daphile
boot press F1 and select “wipe/prepare another storage device as a Daphile installation target.
Attention because all old data on the specified disk will be destroyed!
You can install the system also in the same
USB flash drive used to start the installation.
7. All the settings will be set in the web interface http://daphile.local
so use another PC or a Tablet to open this link.
8. Installing Daphile on the internal disk: Settings->System Firmware->New Installation.
select the target driver, it could be also the same USB flash disk of the first boot to preserve original data and operating system on harddisk.
9. After the reboot (Restart button), continue to configure like show below.
The selection of track is very simple also using web interface.
This operating system need a good PC for the PCM to DSD convertion, follows the cpu consumption on my Dell Vostro 2520 with Intel i5-3210M CPU @ 2.50GHz.
Playing a PCM track with an output rate set to DSD128 only 50% used and no problems while listening.
daphile ~ # top
top - 17:44:00 up 2 min, 1
user, load average: 2.18, 0.95, 0.36
Tasks: 181 total, 1
running, 180 sleeping, 0 stopped, 0 zombie
%Cpu(s):
32.2 us, 7.6 sy, 6.9 ni, 24.1 id, 28.5 wa, 0.0 hi, 0.8
si, 0.0 st
KiB Mem : 8045432 total, 6102984 free,
533272 used, 1409176 buff/cache
KiB Swap:
0 total, 0 free,
0 used. 7402776 avail Mem
PID USER
PR NI VIRT RES SHR S
%CPU %MEM TIME+ COMMAND
5509 user 10 -10 68616
10548 4760 S 50.8
0.1 1:01.98 sox
Playing a PCM track with an output rate set to DSD256 the cpu is full (98.7% used) with many lock.
daphile ~ # top
top - 20:27:16 up 3 min, 1
user, load average: 2.99, 1.29, 0.50
Tasks: 179 total, 3 running, 176
sleeping, 0 stopped, 0 zombie
%Cpu(s): 54.2 us, 1.7 sy, 4.3 ni, 0.3
id, 39.3 wa, 0.0 hi, 0.2 si, 0.0 st
KiB Mem : 8045432 total, 5982912
free, 534116 used, 1528404 buff/cache
KiB Swap: 0 total, 0
free, 0 used. 7401872 avail Mem
PID USER PR NI
VIRT RES SHR S %CPU %MEM TIME+
COMMAND
6894 user 10 -10
64840 9328 4920 R 98.7
0.1 1:14.77 sox
JRiver
The JRiver is a media player software for x64 computers
with Windows (7,8,10), Mac and Linux.
This software
is able to play any high resolution tracks like flac, dff, dsf and also SACD iso
images.
The internal volume does not work on DSD tracks.
Follows the
simple guide to select the PCM to DSD on the fly convertion.
Here the task manager on my Intel i5-5300M CPU @ 2.30GHz.
JRiver + ASIO Proxy
The JRiver is a media player software for x64 computers
with Windows (7,8,10), Mac and Linux.
This software
is able to play any high resolution tracks like flac, dff, dsf and also SACD iso
images.
The internal volume does not work on DSD tracks.
Follows the
simple guide to select the PCM to DSD on the fly convertion with ASIO Proxy, use
the SDM type A or D for the best quality.
If you will use the new ASIO Proxy release follows these setting.
Here the task manager on my Intel i5-5300M CPU @ 2.30GHz.
Foobar2000 + ASIO Proxy
The Foobar2000 is an advanced freeware audio player for
the Windows platform.
It is necessary download some components to add to the
normal installation, these are auto install parts or .dll to insert in the
components directory.
Foobar2000 v1.3.9 or the last available
Use the SDM type A or D for the best quality.
If you will use the new ASIO Proxy release follows these setting.
AK4137
ATTENTION: Some modifications are necessary on DAC module to
work with 2.6 version.
NEWS: the CT7302 chip used like PCM to DSD
converter give better performance.
This is not a software but a chip with the function of
digital sample rate converter.
The my idea is develop a new firmware to
control the AK4137 and integrate a volume control with R2R Shunt Volume .
The AK4137EQ is a 2ch digital sampling rate converter (SRC).
The performances of this chip in the conversion from PCM to DSD is comparable to those of the listed software so this allow the use of less performing PCs and the use of any spdif sources for this DSD converter.
Here the USB Amanero module installed on the AK4137 module and this connected
to DSC1 2.5.
Guide to AK4137 module:
During initial phase keep pressed the button to enter in setup menu to select the USB interface model XMOS or Amanero.
After the banner will be available 2 functions with the same button:
- Short press to switch the input channel
- Long press (more than 0.5 seconds) to change the fiter and output type
1. input RCA, AES, USB, OPT, BNC
2. PCM / DSD type of input received
3.
PCM / DSD input frequency
4. filter SharRoll, SlowRoll, ShoSharp, ShorSlow
5. type of output I32, R32, R24, R20, R16, DSD
6. output frequency for DSD
2.82, 5.64 and 11.2MHz,
Power supply voltage: 5V, operating current of about 100MA
Here some measurement using this module:
and here some frequency responce with different filters
MEAUSREMENTS
Here the distortion at 1KHz and 1.6Vrms output.
Here the distortion at 100Hz and 1.2Vrms output.
The distortion and noise of version 2.6
POWER SUPPLY
In order to have all the power supply necessary for this project I have buy a
power supply module on Alixpress.
High Speed Low Noise
Triple Independent Linear Regulator Power Supply only 14-17$.
In the order ask for 3.3V, 5V (AK4137 if necessary) amd 7.5V and add a good 9VAC 30VA transformers.
XMOS compatibility
The new 2.52 and 2.6.2 are compatible with XMOS USB module that are cheaper than Amanero but we don't suggest this solution because the persormances are not the same.
In the following plot in red the XMOS, in
green the Amanero and in
violet the noise of ADC with shorted input.
Maximum anti-aliasing for clarity. The conditions are the same, playing
via AlbumPlayer a 1KHz DSD128 file generated by saracon
PHOTOS
Follows the photos of a my friend with a DSC 2.6 integrated in an Audio Note Kondo M77 clone.