[abartels]

  I had an idea!
to use Teralink ADuM4160 USB Isolator board, but D+ and D- to connect separately direct from computer.
http://www.ab-system.hk/index.php?route=product/product&path=73&product_id=63
 
In this case will be isolated : usb Vcc (+5V) and shield and GND!!!

 
Very good tip!
I will try this one for MX-U8!
 
Thanks for sharing

 

[mz2014]

Hi everyone.
Which USB interface will be the best and how can I plug it to DAC board ( if it will work ? ).
Thanks
 
http://www.diyinhk.com/shop/audio-kits/69-isolated-xmos-dsd-dxd-384khz-high-quality-usb-to-i2sdsd-pcb-with-ultralow-noise-regulator.html#/xmos_option-xmos_pcb
http://www.audiophonics.fr/en/interfaces/amanero-combo-384-digital-interface-usb-384khz-to-i2sdsd-p-7403.html
http://item.taobao.com/item.htm?spm=0.0.0.0.li1MtV&id=18075891198&b=danpin_zhutu_up1

 

[abartels]

   
This is definitely a contender, 
 

1. Using three NDK NZ2520SD Ultra low phase noise oscillator
2. Batch 8pcs+ includes free microsoft windows signed driver and device name shown as genuine XMOS USB Audio

http://www.diyinhk.com/shop/audio-kits/58-xmos-dsd-dxd-384khz-high-quality-usb-to-i2s-pcb.html#/xmos_option-xmos_and_led_pcb

 
Nice find hgpsemaj!
 
It looks that i will build my own DDC real soon 

 

 

[abartels]

New find:
 
This one is even isolated (NZ2520SD's for audio on isolated side,,,) - this means you can feed them with seperate powersupply!
 
http://www.diyinhk.com/shop/audio-kits/69-isolated-xmos-dsd-dxd-384khz-high-quality-usb-to-i2sdsd-pcb-with-ultralow-noise-regulator.html
 

 
 
 
HDMI - print:
 
http://item.taobao.com/item.htm?spm=2013.1.0.0.VKHlno&id=41715842497
 

 
 
The USB isolator:
 
http://www.ab-system.hk/index.php?route=product/product&path=73&product_id=63
 
 

 
 
The regulator (it's double version, one for xmos pcb, one for NDK NZ2520SD's)
 
http://www.diyinhk.com/shop/audio-kits/73-08uv-ultralow-noise-dac-power-supply-regulator-33v5v-1ax2.html
 

 
Who can find a nice aluminium enclosure with thick black anodised and brushed faceplate?
 
 
Cheers 

 

[prot]

Who can find a nice aluminium enclosure with thick black anodised and brushed faceplate?


Cheers 

Something which will work http://www.ebay.com/itm/400524540484.
Prolly a million of those on ebay. Just ask that shop for the exact model you want, they seem to have quite a lot of options.

And good luck with the build, the plan looks very good.

 

[korn-fi]

Can it work at USB high speed ?

 

[pakultra]

I did it!
 
Now my U12 can work like my Nad D 1050 with 2-wire USB cables (D+ and D- only, no USB positive, no negative, no shield connection).
 
Here is how:
 
Step 1) the U12 relay needs to be bypassed by a separate wire, and
 
Step 2) the U12 ground needs to be connected to U12 IEC ground (this removes the need for USB ground or Shield)
 
Step 3) the XMOS must be either A) taught not to check for USB positive power by changing corresponding instructions in its firmware or B) tricked into believing it has seen usb power while there is none;
 
A) can only be done by changing corresponding instructions in Gustard firmware; until a modified firmware is made available, we can do B), which is what I just did. I connected U12's own +5 positive power to its USB socket's Vcc pinout through a D4004 diode.
 
Originally, I wanted to use a pull up resistor. I tried 820k, 470k and 200 ohm but none of them worked. I don't have smaller resistors on hand. So, for the time being, I will settle for a diode. However the diode only protects U12, it can not prevent U12's power from flowing out to computer USB port if accidentally connected with a regular USB cable. Caution has to be taken not to connect USB Vcc to a modded U12.
 
Still, we need Gustard to make a modified firmware so that there will be no need to do B) in step 3.
 
Finally, I'd like to thank our excellent forum members hgpsemaj for helping make this mod possible and abartels for pioneering ground connection to IEC!
 
Cheers!

 

[hgpsemaj]

  New find:
 
This one is even isolated (NZ2520SD's for audio on isolated side,,,) - this means you can feed them with seperate powersupply!
 
http://www.diyinhk.com/shop/audio-kits/69-isolated-xmos-dsd-dxd-384khz-high-quality-usb-to-i2sdsd-pcb-with-ultralow-noise-regulator.html
 

 
 
 
HDMI - print:
 
http://item.taobao.com/item.htm?spm=2013.1.0.0.VKHlno&id=41715842497
 

 
 
The USB isolator:
 
http://www.ab-system.hk/index.php?route=product/product&path=73&product_id=63
 
 

 
 
The regulator (it's double version, one for xmos pcb, one for NDK NZ2520SD's)
 
http://www.diyinhk.com/shop/audio-kits/73-08uv-ultralow-noise-dac-power-supply-regulator-33v5v-1ax2.html
 

 
Who can find a nice aluminium enclosure with thick black anodised and brushed faceplate?
 
 
Cheers 

 
 
Hello Abartels,
 
Let's do it once and for all. How about pair all these up?
 
http://soekris.com/products/audio-products/dam1021-01.html

 
The dam1021 is a DAC module based on a discrete R-2R sign magnitude DAC design, with FPGA based FIFO buffering/reclocking and custom digital filters, < 1 ps jitter clock generator, with 28 bit resolution so there is headroom, oversampling up to 3.072 Mhz. Up to 24 bit / 384 Khz input from SPDIF, I2S and USB (via USB to I2S interface board), with isolation on the I2S interface. The board is very flexible, with digital volume control and filter parameters that can be downloaded. The board is fully firmware upgradable over a simple serial connection, which enables new features later on. For now we plan to add digital crossover filters soon.

The basis R-2R network has an output voltage of 1.4V RMS and output impedance of 625 ohm and can therefore drive a lot of things directly. There is also onboard balanced output drivers that can drive high impedance (>= 300 ohm) headphones directly. The power supply is also onboard, just add a 5W+ toroid transformer.
 
 
There is a threads/forum on this item, please refer:
 
http://www.head-fi.org/t/754547/the-soekris-r-2r-dac-technical-details

 

[hgpsemaj]

  I did it!
 
Now my U12 can work like my Nad D 1050 with 2-wire USB cables (D+ and D- only, no USB positive, no negative, no shield connection).
 
Here is how:
 
Step 1) the U12 relay needs to be bypassed by a separate wire, and
 
Step 2) the U12 ground needs to be connected to U12 IEC ground (this removes the need for USB ground or Shield)
 
Step 3) the XMOS must be either A) taught not to check for USB positive power by changing corresponding instructions in its firmware or B) tricked into believing it has seen usb power while there is none;
 
A) can only be done by changing corresponding instructions in Gustard firmware; until a modified firmware is made available, we can do B), which is what I just did. I connected U12's own +5 positive power to its USB socket's Vcc pinout through a D4004 diode.
 
Originally, I wanted to use a pull up resistor. I tried 820k, 470k and 200 ohm but none of them worked. I don't have smaller resistors on hand. So, for the time being, I will settle for a diode. However the diode only protects U12, it can not prevent U12's power from flowing out to computer USB port if accidentally connected with a regular USB cable. Caution has to be taken not to connect USB Vcc to a modded U12.
 
Still, we need Gustard to make a modified firmware so that there will be no need to do B) in step 3.
 
Finally, I'd like to thank our excellent forum members hgpsemaj for helping make this mod possible and abartels for pioneering ground connection to IEC!
 
Cheers!

 
Hello Pakultra,
 
Congratulation, really its a very good discovery. It seem our modification works of U12 is going from strength to strength.
 
 
 
Regards,
 
 
 
hgpsemaj

 

[Voltot]

Could digital signal D+ D- be "dirty" and influence to sound quality?

 

[prot]

also interested about the eventual SQ improvements ... the modifications seem to be cheap enough and, with some more detailed instructions, even a beginner like me may be able to do it.
But is the SQ so much better than an OOTB Gustard? Also, is it better than a battery and a dualhead USB cable combo? (i.e. clean power for about $50 without even opening the box)

guess what I'm trying to figure out is: are those mods worth the effort and the risk of bricking your U12 !? Even for someone with limited soldering experience !?

 

[abartels]

   
 
Hello Abartels,
 
Let's do it once and for all. How about pair all these up?
 
http://soekris.com/products/audio-products/dam1021-01.html

 
The dam1021 is a DAC module based on a discrete R-2R sign magnitude DAC design, with FPGA based FIFO buffering/reclocking and custom digital filters, < 1 ps jitter clock generator, with 28 bit resolution so there is headroom, oversampling up to 3.072 Mhz. Up to 24 bit / 384 Khz input from SPDIF, I2S and USB (via USB to I2S interface board), with isolation on the I2S interface. The board is very flexible, with digital volume control and filter parameters that can be downloaded. The board is fully firmware upgradable over a simple serial connection, which enables new features later on. For now we plan to add digital crossover filters soon.

The basis R-2R network has an output voltage of 1.4V RMS and output impedance of 625 ohm and can therefore drive a lot of things directly. There is also onboard balanced output drivers that can drive high impedance (>= 300 ohm) headphones directly. The power supply is also onboard, just add a 5W+ toroid transformer.
 
 
There is a threads/forum on this item, please refer:
 
http://www.head-fi.org/t/754547/the-soekris-r-2r-dac-technical-details

 
The Soekris R-2-R dac could be a contender, but i'm not 100% sure. There's also a relative new AKM dac (also available at DIYINHK) AK4495SEQ which goes up to 768kHz.
And, maybe i want to seperate DDC from DAC,,,,

 

[abartels]

  I did it!
 
Now my U12 can work like my Nad D 1050 with 2-wire USB cables (D+ and D- only, no USB positive, no negative, no shield connection).
 
Here is how:
 
Step 1) the U12 relay needs to be bypassed by a separate wire, and
 
Step 2) the U12 ground needs to be connected to U12 IEC ground (this removes the need for USB ground or Shield)
 
Step 3) the XMOS must be either A) taught not to check for USB positive power by changing corresponding instructions in its firmware or B) tricked into believing it has seen usb power while there is none;
 
A) can only be done by changing corresponding instructions in Gustard firmware; until a modified firmware is made available, we can do B), which is what I just did. I connected U12's own +5 positive power to its USB socket's Vcc pinout through a D4004 diode.
 
Originally, I wanted to use a pull up resistor. I tried 820k, 470k and 200 ohm but none of them worked. I don't have smaller resistors on hand. So, for the time being, I will settle for a diode. However the diode only protects U12, it can not prevent U12's power from flowing out to computer USB port if accidentally connected with a regular USB cable. Caution has to be taken not to connect USB Vcc to a modded U12.
 
Still, we need Gustard to make a modified firmware so that there will be no need to do B) in step 3.
 
Finally, I'd like to thank our excellent forum members hgpsemaj for helping make this mod possible and abartels for pioneering ground connection to IEC!
 
Cheers!

 
You're welcome Pakultra!
Nice find 

 

[abartels]

also interested about the eventual SQ improvements ... the modifications seem to be cheap enough and, with some more detailed instructions, even a beginner like me may be able to do it.
But is the SQ so much better than an OOTB Gustard? Also, is it better than a battery and a dualhead USB cable combo? (i.e. clean power for about $50 without even opening the box)

guess my Q is: is it worth the effort and the risk of bricking your U12 !?

 
To be honest, the most important upgrade are the XO's, they will bring you a HUGE SQ improvement.
Replacing caps for psu, changing the rectifiers, decoupling from polluted sub-power/signal, it all helps getting better SQ, but XO's are a MUST.
 
If i would have to explain in percentages in SQ increase from stock unit until now:
 
NDK NZ2520SD's                   70%
Panasonic FC caps                10%
MUR120 rectifiers                   5%
USB-decoupling gnd               10%
3M AB51000S                        5%
 
I'm aware of the complexity of soldering the NDK's, but if you follow my instructions from earlier post, it is very good doable.
And, you always could go for the Crysteks, they are much easier to replace the standard clocks.
 
Bricking U12 doesn't happen when follow instructions carefully. De-soldering components can be a bit tricky, always take
care that you don't heat too much and not pulling components out while they still are stuck, because otherwise you could
destroy via's to inner multilayers.
 
The XO's are simple to replace, if you've got good eyes (which I DON'T have,,,), soldering NDK's is possible, otherwise
use magnifying glasses.

 

[hgpsemaj]

  Could digital signal D+ D- be "dirty" and influence to sound quality?

 
First of all, usb cable is not designed for carrying SQ audio digital signal, and that's why we have Tanor, Xmos & etc. to convert the format back to SPDIF / AES. And also, we have USB-32 to combat this badly designed cable.
 
IMO, when those signals(+, -, D+, D-) flow at high speed, they create flux, and under 'moment of inertia', those signals would affect each other and influence to sound quality.
So, a double usb cable(i.e. Power/Digital) could minimise this phenomenon.