[Dynobot]

Quote:

That's the only dongle I've seen so far that runs ADuM5000, ensuring a full galvanic isolation between the device and the host.

 
There are two independent isolators which works individually for USB. One of them is USB digital signal isolation device, ADUM4160 of Analog Devices, which purify signal of DDC. The other is USB power isolation device, ADUM5000 of Analog Devices. ADUM5000 works to isolate input power and purify it again to supply.

 

[leeperry]

 

Where did you order that lee?????

 
https://www.aimagin.com/store/amg-usb-isolator.html
 
I should get it next week. That's one darn attractive toy for slightly OCD'ed peeps like us

 
They also have a survey draw contest to win one: https://www.aimagin.com/

 

[Dynobot]

So what you gonna use for power??
 
 
Quote:

 

Where did you order that lee?????

 
https://www.aimagin.com/store/amg-usb-isolator.html
 
I should get it next week. That's one darn attractive toy for slightly OCD'ed peeps like us

 
They also have a survey draw contest to win one: https://www.aimagin.com/

 

[leeperry]

Well, I've had some emails with Aimagin, they were rather dubious about my use for USB audio. That's when they told me that ADI supervised their design, that the computer side of ADuM4160 was fed from the USB 5V power, and that the device side of ADuM4160 was going through ADuM5000...in order to provide a full galvanic isolation on both the data and power lines.
 
If you look at Oleg's board, you can read: 

ADuM4160 works at full/low speed and uses built-in transformers. The uplink (host) side of it is powered by USB bus, the downlink (peripheral) side uses external supply. [..] The PCB also contains a 5V switch mode regulator with wide input range. It supplies downlink side of AdUM4160 and bus-powered device connected to it, if necessary.

 
So whatever dongle, they all feed the noisy computer power to the uplink side of ADuM4160...there is no way around this AFAIK.
 
My Bravo is fed from a linear regulated "Supplier" PSU, and this dongle has been certified by ADI(which is a strong asset). It should trump any other USB Isolation dongle when feeding your USB device off a clean discrete PSU. I'll let you guys know after I'll have done more testing

 
Another solution would be to use a USB3 PCI-E board with a Molex connector, and feed it a clean 5V PSU, hah! Now, that'd be a wild trick to try

 
I'm so happy with the SQ off my noname cheap Chinese NEC USB3.0 PCI-E board, that I've bought a MSI that seems to have much higher quality components and an EMI shield: http://eu.msi.com/index.php?func=proddesc&maincat_no=1&prod_no=2037
 
It's lying on my desk atm, I will mount it in a few. It seems to be using the very same kind of caps as the new "Firestone Spitfire" DAC:

 

[regal]

Quote:

Well, I've had some emails with Aimagin, they were rather dubious about my use for USB audio. That's when they told me that ADI supervised their design, that the computer side of ADuM4160 was fed from the USB 5V power, and that the device side of ADuM4160 was going through ADuM5000...in order to provide a full galvanic isolation on both the data and power lines.
 
If you look at Oleg's board, you can read: 

ADuM4160 works at full/low speed and uses built-in transformers. The uplink (host) side of it is powered by USB bus, the downlink (peripheral) side uses external supply. [..] The PCB also contains a 5V switch mode regulator with wide input range. It supplies downlink side of AdUM4160 and bus-powered device connected to it, if necessary.

 
So whatever dongle, they all feed the noisy computer power to the uplink side of ADuM4160...there is no way around this AFAIK.
 
My Bravo is fed from a linear regulated "Supplier" PSU, and this dongle has been certified by ADI(which is a strong asset). It should trump any other USB Isolation dongle when feeding your USB device off a clean discrete PSU. I'll let you guys know after I'll have done more testing

 
Another solution would be to use a USB3 PCI-E board with a Molex connector, and feed it a clean 5V PSU, hah! Now, that'd be a wild trick to try

 
I'm so happy with the SQ off my noname cheap Chinese NEC USB3.0 PCI-E board, that I've bought a MSI that seems to have much higher quality components and an EMI shield: http://eu.msi.com/index.php?func=proddesc&maincat_no=1&prod_no=2037
 
It's lying on my desk atm, I will mount it in a few. It seems to be using the very same kind of caps as the new "Firestone Spitfire" DAC:

The designers I've spoken with have told me the Adum isolators add more noise than a computers ground and are detrimental to the sound.    Have you taken any measurements to show that this adum is worthwhile?
 

 

[Dynobot]

I would be interesting to see that the Adum adds more noise than a computer when most everyone who uses them report an increase in fidelity.  If so, that would be a total surprise.
 
 
I think however that looking at all the work arounds and money spent on trying to optimize the computer as a front end it might be cheaper and easier in the long run to get a good transport.  All be it not as convenient as a computer.

 

[regal]

Quote:

I would be interesting to see that the Adum adds more noise than a computer when most everyone who uses them report an increase in fidelity.  If so, that would be a total surprise.
 
 
I think however that looking at all the work arounds and money spent on trying to optimize the computer as a front end it might be cheaper and easier in the long run to get a good transport.  All be it not as convenient as a computer.

The way it was explained to me by a very respected digital designer was to use the high performance shunt powersupplies (not the computers +5V)  but share the computers ground without trying to galvanically isolate it with the Adums,  then use the typical pulse transformer on the output of course for the galvanic isolation.   I guess active devices providing ground isolation in digital audio were never very successful (going back several years) so I am surprised at the popularity of the Adum here.  I think its popularity may just be  that it gives a convenient means to plug in a quality powersupply in leui of the USB 5+V,  just saying in may be worth trying to bypass the adum.  Trial and error thats all.

 

[Dynobot]

I understand, in fact i own a Adum as well.
 
As you can see here plugged into the DI.  Logic, reason, tests, expert opinions might not agree, but for some reason my ears hear an improvement.  Not so much with the DI but marginally so when plugged directly into a Dac.  Like you said, its always good to scrutinize tweaks to confirm that the claims are true.  Unfortunately the only test equipment I have are my ears, which is why I said it would be interesting to see lab results that counter my listening impressions. 
 

 

[leeperry]

 

Originally Posted by Dynobot /img/forum/go_quote.gif
 
the only test equipment I have are my ears

Not good enough, don't trust them...it doesn't matter if it sounds good, just don't trust them

 

[Mad Max]

Quote:

I understand, in fact i own a Adum as well.
 
As you can see here plugged into the DI.  Logic, reason, tests, expert opinions might not agree, but for some reason my ears hear an improvement.  Not so much with the DI but marginally so when plugged directly into a Dac.  Like you said, its always good to scrutinize tweaks to confirm that the claims are true.  Unfortunately the only test equipment I have are my ears, which is why I said it would be interesting to see lab results that counter my listening impressions. 
 

No casing for it?

 

[leeperry]

oh yah, on that point Aimagin's dongle has a mil-spec insulating coating sprayed on and ADuM5000 can get rather hot FWIR. I'm not sure how I'm gonna build it a nice faraday cage just yet ^^

 

[Dynobot]

Well mine is naked and will probably stay that way...

 

[leeperry]

Shielding EMI/RFI's would only help IMHO. The 4160 datasheet also has a section about EMI's.
 
I should get my Aimagin dongle on monday, and I've found a few metal boxes that could easily be modded. At some point, I did wrap the USB2ISO dongle into several layers of electrician tape and aluminium foil

 
I still rest my case than an external PSU is pointless w/ ADuM4160 when you have a clean PSU fed to your device...as it'll always feed the computer USB power on the uplink side anyway. The reason why the USB2ISO and Oleg's dongles sound different is due to their designs IMHO, not to the external PSU...which is redundant to say the least, and none of them was certified by ADI or includes ADuM5000...so they only provide galvanic isolation on the data lines, but not on the downlink power lines to 4160: 

 Aimagin's dongle adresses those two issues, very eager to try it

 
The 4160 eval.board does include 5000 for a good reason...the same reason why they used both in this thing as well(even though they claim to have put 5000 on the uplink side, which goes against ADI's guidelines).

 

[leeperry]

ok, it's on  
 
good news is: I've got sound

 
more impressions later.

 

[leeperry]

so far ADuM5000 isn't even warm to the touch after a few hours, so the dongle is definitely going to get the faraday treatment.
 
I'll run more tests and comparisons later, but so far the SQ is noticeably clearer than w/ my ADuM4160-only dongle. There's indeed a good reason why both were used on the official eval.board, and why they were also both used in that CARAT-T2 transport...full galvanic isolation is a pre-requisite w/ digital audio IME, that's the very reason why S/PDIF has been prevailing over USB for so long...Shh. Shh. Shh. Shh. Do you hear that? It's the winds of change