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Network Audio DAC
Dec 2018 - preview
 

INTRODUCTION

I can guarantee that  DSC1 2.5 / 2.6 is the best digital source and the maximum sonic performance can only be achieved using the software HQPlayer desktop.

This software is available for Windows, Linux and macOS and it have many algorithm for noise filters which allow many sound variations.

The embedded version of HQPlayer is designed for building Linux-based music playback devices and digital audio processors.

HQPlayer embedded is a daemon server running on a dedicated hardware so it is immune to any interference allowing a perfect reproduction of any track at high bitrate also during the PCM to DSD on-the-fly convertion.

About the DAC hardware I keep experimenting new solutions based on DSC1 with Pavel Pogodin and here the Pure DSD DAC with and without USB input.

In the following photos the new DAC module with Amanero Combo384 USB interface (left) and with the BeagleBone board (right).

The NAA protocol has been design by Jussi Laako of Signalyst and this use normal full TCP/IP stack plus XML with some crypto algorithms for authentication so it is very simple if compared to professional standards which have as main objective the synchronism of the clock of various slave devices.

The NAA run without problem on 100 Mbps LAN at DSD512 data rate.

Here my implementation with volume control by CT2 DACT stepper attenuator with the Bent Audio remote control and the CT3 DACT as analog input selector.



Here the implementation of Pavel Pogodin using RoonServer + HQPlayer Embeded + new DSC2.


CHOICE OF HARDWARE

This new DAC by Pavel Pogodin is compatible with BeagleBone Black and Green but the last one have a better build and no extra hdmi.
On this little board run a very little custom Linux near to a firmware able to work simultaneously with RoonBridge and the Network Audio Adapter for HQPlayer

The BeagleBone Green is based on the open-source hardware design with the Processor: AM335x 1GHz ARMŽ Cortex-A8, 512MB DDR3 RAM and 4GB 8-bit eMMC on-board flash storage.

The normal power supply input for the BeagleBone is the micro USB but it is possible to provide 5V to the main board from an expansion board.

By supplying a 5V signal into the VDD_5V rail, the main board can be supplied. This voltage must not exceed 5V.

You should not supply any voltage into any other pin of the expansion connectors.


There are 2 more power supply necessary for the DAC module.

In order to have these 3 voltages, 5V 1A for the BeagleBone Green, 5V for the DAC and 8V for the DAC  I have buy these 2 power supply module on Alixpress.

High Speed Low Noise Triple Independent Linear Regulator Power Supply only 10-15$ and LT1083 adjustable power supply board only 5-15$ for the BeagleBone (to set at 5V).

The BeagleBone use the TS65217 chip power management and the DC supply must ramp up sufficiently rapidly (within 50 ms) to trigger power-up otherwise this chip enters some kind of lockup state and cpu does not switch-on.

In the LT1083 module I have replaced the 4700uF with a 1000uF 16V, eliminated the yellow fuse and connected the heatink to ground.
 

 In the order of the Triple Independent Linear Regulator ask for 3.3V (Amanero if necessary),  5V and 8V.

     

Add a good 9V 30VA and a 6.5 - 7V 30VA transformer.

The power supply transformer has been created on my specification with an extreme low flux.

The primary has been calculated for 260V instead of 220V to keep the flux at 14000 gauss.

The company used for this product is Italtras.

V primary   gauss   V primary   gauss V primary    
220   17000 1.18 259.6   14000 260V    
V second. A sec VA 17000/14000 V second. A second. VA V second. A sec VA
15 0.2 3 1.18 17.7 0.4 7.08 18 0.2 3.6
15 0.2 3 1.18 17.7 0.4 7.08 18 0.2 3.6
6.5 2 13 1.18 7.67 0.2 1.534 7.7 3 23.1
9 1 9 1.18 10.62 5 53.1 10.6 1 10.6
  total 28     total 68.794   total 40.9

In my case there is an added seconady 18V-0-18V to power a BUF634 buffer to isolate the main output from the subwoofer of my Monitor 4.

 

 

 

OPERATING SYSTEM INSTALLATION

It is necessary install the BeagleBone firmware designed specifically for this board.

Installation

  1. Uncompress with 7z the file Arch_Botic_DSC2.gz
  2. Copy on a 16Gb micro SD using the Windows software Win32DiskImage
  3. Insert the micro SD on BeagleBone module
  4. Connect the USB to serial adapter to PC
  5. Identify your new serial port on Windows
  6. Connect the USB to serial adapter to BeagleBone module
  7. verify console with the Putty Windows software.
  8. Held down the Boot button
  9. power the BeagleBone  module
  10. check on serial the system boot of botic system and not the normal
  11. login with userid root and password root
  12. use the script /opt/tools/SD_to_eMMC.sh to writes the operating system to the internal memory of the eMMC
  13. extract the micro SD
  14. disconnect the power
  15. verify the start of the botic system at power on
  16. connect the BeagleBone module on DAC

1. Uncompress with 7z the file Arch_Botic_DSC2.gz


2. Copy on a 16Gb micro SD using the free windows software Win32DiskImage.


4. Identify your new serial port (here COM5) on Windows Device Manager



5. Connect the USB to serial adapter to BeagleBone module

Now you need to connect the PC to the BeagleBone board on console using an USB to serial adapter for 3.3V.


The most common adapter is the Profilic PL2303 but in many case on the last Windows versions the driver does not recognize the device, I have used this guide to solve the problem but I have got some Windows crash with this old driver.

Use only ground, tx and rx pin from USB to serial adapter.

 

6.The Putty is an open source software a serial / SSH client.

   


 

THE HQPLAYER / HQPLAYERD CONFIGURATION

To configure the HQPlayerd open the website on port 8088.

I suggest to set the Output mode to SDM to convert output in DSD, the modulator to ASDM7 or ADSM5 (if no cpu resource available with 7) and Bitrate at 11289600 Hz or 12288000Hz for a DSD256 setup.