[abartels]

   
Hi !  i have a question about the U12
 
I have noticed that if i isolate the usb input from the pc usb power lines it does not switch on
IMHO this is a very big limit indeed. 
The unit should be working also connected with a usb data only cable providing electrical isolation with the pc.
However ....   is there any way to make it working with electrical connection to the pc and no usb power supply ?
I do not know if my question is clear
Thanks a lot,  gino

 
Hi Gino, not to be picky, but please read the last pages, we worked hard to get it fixed, so please read postings.
 
Cheers,
Alex

 

[abartels]

  Couldn't resist and put the Elfidelity filters including USB-card in my AudioPC. ControlPC still has no Elfidelity cards.
 
Sounds FANTASTIC, but PROBLEM with USB-card. USB-card won't work with U12, even not with standard USB cable.
Can connect keyboard and mouse to the card, they work. Very strange problem.
 
 
MX-U8 is burnin-in, haven't test connection to USB-card with it. Will try later on.
 
 
 
Filters are amazing 

 
Elfidelity AXF-100 Pro Usb card works now!
 
Procedure:
 
FIRST uninstall xmos drivers and RESTART your pc.
Connect your U12 (or MX-U8 or other device) to the AXF-100 Pro and install xmos drivers.
 
Restart pc, and you're done!!
 
Restarts are VERY important, without it wont work.
 
Cheers,
Alex

 

[Voltot]

So we need Elfidelity AXF-100 or PPA or Sotm usb cards if our converter eats digital signal only (D+, D-)?

 

[ginetto61]

   
Hi Gino, not to be picky, but please read the last pages, we worked hard to get it fixed, so please read postings.
 
Cheers,
Alex

 
Hi Alex i tried hard but it is too technical for me. I had to give up.
My skills are very limited and i would never mess with the internal. 
The fact that it does not provide electrical isolation is a huge drawback in my wiew ...
this should be a basic design requirement for any usb to spdif interface.
It is written everywhere how dirty is pc usb voltage.
I will try just a usb noise filter. That i can do also myself.  
I have one i bought on ebay time ago.
Thanks anyway,  gino 

 

[hgpsemaj]

I believe not all our members could manipulate electronic workmanship. There are many alternatives which could overcome 5V/Ground drawback in our U12. Aqvox USB Low-Noise 5V Isolated Linear Power Supply is one of the tactics which may solve our U12 drawback. But the thing is, who would pay EUR98.00 for an adaptor and a piece of wire.
So, I've the following proposal:
 
RMB40.00 excluding postage,

 
 
RMB248.00 Linear Power Supply 2 x 5V output.

 
 
And later, you may add another US$59.95 for this 0.8uV ultra low noise regulator, also '3.3V/5V  1A' x 2

 
 
Please comment.
 
 
Regards,  
 
hgpsemaj

 

[ginetto61]

I believe not all our members could manipulate electronic workmanship. There are many alternatives which could overcome 5V/Ground drawback in our U12. Aqvox USB Low-Noise 5V Isolated Linear Power Supply is one of the tactics which may solve our U12 drawback. But the thing is, who would pay EUR98.00 for an adaptor and a piece of wire.
So, I've the following proposal:
RMB40.00 excluding postage,

RMB248.00 Linear Power Supply 2 x 5V output.

And later, you may add another US$59.95 for this 0.8uV ultra low noise regulator, also '3.3V/5V  1A' x 2

Please comment.
Regards,  
hgpsemaj

 
Hi and thanks for the suggestion.
If it is the Teradak U9 i have already one. I should have said that. Sorry.
By the way a really nice unit i can sincerely recommend to anyone. 
My point was just a trivial comment.
A well designed usb to spdif converter MUST have in its design requirements its own low noise power supply and provide electrical isolation from the pc
These are basic requirements because everyone knows how dirty is usb voltage. 
Another external usb power supply should be redundant.  I see now sadly that with the U12 is not the case.
They have done a very competent unit ... why slip on this basic thing ... i do not understand really. 
Personally i do not like toroidal in digital equipment, but that is just me. 
So to end the ramblings i would like to avoid to use another usb power supply ...
my rig looks more like a christmas tree than an audio system
Thanks a lot again,  gino   

 

[pakultra]

Findings on U12 cap values:
 
I replaced my two 2200uf ultra-low impedance (14 mohm) Nichicon caps with two 5600uf ultra-low ESR panasonic FC caps for experiment. To my surprise, the breathtaking imaging is gone. Everything is a little laid back. To make sure I wasn't imagining differences, I put my 2200uf Nichicon back in, the imaging is back. It turns out that the original cap value of 2200uf is pretty optimal.
 
Some people insist that audio sounds better with smaller caps so that the circuit is powered more of the time directly by transformer instead of by capacitors. That's the reason I didn't increase the cap value when I replaced them. My experiments with 5600uf caps confirmed this.

 

[Walderstorn]

This thread turned into an advanced/modders-only thread for the most of it jesus christ i cant understand nothing of what you guys are talking about lol, so i will just ask 2 little things:
 
Does that weird usb cable with separate data - power work after all ?
 
 
@abartels could u provide a proper picture of that cable that you put inside to make the noise go away or did u scrap that idea and just used the pci-e/usb card?

 

[Jamiee]

I personally use a JCAT USB card powered by the JCAT Battery PSU, - and a Light Harmonic Lightspeed (twin) USB cable.
All together they are a potent low-noise combination.
 
Not cheap, but well worth it!

 

[pakultra]

  This thread turned into an advanced/modders-only thread for the most of it jesus christ i cant understand nothing of what you guys are talking about lol, so i will just ask 2 little things:
 
Does that weird usb cable with separate data - power work after all ?
 
 
@abartels could u provide a proper picture of that cable that you put inside to make the noise go away or did u scrap that idea and just used the pci-e/usb card?

@Walderstorn,
 
D+ and D- two wire data only connection is working now. No positive, no ground in usb wire, data wire shielding connected at U12 only and disconnected from PC.
 
Here is how I did it:
 
 
:
 

 
 
Warning: Do Not use regular usb cable after these mods. You might damage your U12 or PC if you use regular four wire usb cables. Absolutely no USB Positive connection at any time!
 
Regarding Step 3), please note that we hope Gustard will issue a firmware revision to disable XMOS's Vcc detection function. Once that is done, there will be no need for Step 3. Step 3 connects U12 + 5 with USB  Vcc, which is BAD and Dangerous! Take cautions here.
 
No wiring on the upper side of the pcb:
 

 
I replaced the spdif transformer and 2200 uf caps. There are no hookup wires on this side. U12 still look nice and clean.

 

[Voltot]

Thanks a lot. It's works. I am using Oyaide NEO d+ Class S usb cable with isolated ground, Vcc and shield by...insulating tape! Big sound improvement, much cleaner.

 

[Walderstorn]

@pakultra thank you very much but turned out to be much more complex than i thought it would be, definitely not something im confortable trying. I guess my friend (the owner of the u12) is screwed and he's probably going to sell it, since he finds it (and so do i) awful that they could've ignored this issue when manufacturing, seems like a huge oversight and i dont think a firmware update will be able to fix it.

 

[abartels]

  Findings on U12 cap values:
 
I replaced my two 2200uf ultra-low impedance (14 mohm) Nichicon caps with two 5600uf ultra-low ESR panasonic FC caps for experiment. To my surprise, the breathtaking imaging is gone. Everything is a little laid back. To make sure I wasn't imagining differences, I put my 2200uf Nichicon back in, the imaging is back. It turns out that the original cap value of 2200uf is pretty optimal.
 
Some people insist that audio sounds better with smaller caps so that the circuit is powered more of the time directly by transformer instead of by capacitors. That's the reason I didn't increase the cap value when I replaced them. My experiments with 5600uf caps confirmed this.

 
Hi pakultra, the downside on modifying audio equipment is that you have to let the replaced components BURN-IN, so, put those Pana's back in and let it them burn-in for at least 100 hours!
You will be surprised what they finally bring you!
 
Cheers

 
Alex 

 

[abartels]

  This thread turned into an advanced/modders-only thread for the most of it jesus christ i cant understand nothing of what you guys are talking about lol, so i will just ask 2 little things:
 
Does that weird usb cable with separate data - power work after all ?
 
 
@abartels could u provide a proper picture of that cable that you put inside to make the noise go away or did u scrap that idea and just used the pci-e/usb card?

 
Hi Walderstorm,
 
I didn't took a picture, it's just a simple wire extracted from a powercord, connected from grounpin at IEC320 connector to a negative feed at psu cap.
 
And yes, I use it in my U12, then there's no need for complex galvanic ground isolation, just cut black wire and groundschiel in usb cable at pc side.
 
 
Regards,
Alex

 

[abartels]

 
@Walderstorn,
 
D+ and D- two wire data only connection is working now. No positive, no ground in usb wire, data wire shielding connected at U12 only and disconnected from PC.
 
Here is how I did it:
 
 
:
 

 
 
Warning: Do Not use regular usb cable after these mods. You might damage your U12 or PC if you use regular four wire usb cables. Absolutely no USB Positive connection at any time!
 
Regarding Step 3), please note that we hope Gustard will issue a firmware revision to disable XMOS's Vcc detection function. Once that is done, there will be no need for Step 3. Step 3 connects U12 + 5 with USB  Vcc, which is BAD and Dangerous! Take cautions here.
 
No wiring on the upper side of the pcb:
 

 
I replaced the spdif transformer and 2200 uf caps. There are no hookup wires on this side. U12 still look nice and clean.

 
Nice job pakultra, I didn't took time to measure all of the pins to find groundpin, AES transformer pin 1 is a good find, will remove wire on top and modify to this pin, look cleaner indeed.
 
About relay bypassing, It's a nice find, but I'm not very fond of this mod because of accidental connecting standard usb cable will destroy U12 or usb-port from pc.
 
I tried feeding relay with batterypower, there's no sq improvement in comparrison with feeding relay with usb power, at least, with my usb cable.
 
 
Cheers 

 
Alex