USB with separate linear power supply

[dan1502]

I have recently picked up an M2Tech Hiface 2 second hand. I'm not sure whether it will end up between my O2 Joggler running Squeezeplay OS and Ehanced Digital Output and Arcam AVR250 AV amp or where I currently have it which is on the main hifi system beween a recently built silent HTCP running JRiver and a Benchmark DAC1 HDR (leading to NCore monos).

It is not working correctly with the Joggler which I believe is probably due to limited USB power from the Joggler which I understand to be a common issue.

So my plan is to make something akin to the Aqvox USB audio power supply, galvanical isolated, audiophile USB Power supply, isolated USB low noise transformer, USB DAC power supply, audiophile power supply but not to spend so much.

I've found a suitable 5V 1A linear power supply as sold by itemaudio but without the markup. Itemaudio also sell these:

Microtik 5V USB Injector

My question is whether these isolate the power from the PC from the USB output rather than just add to it i.e. is the power from the USB connector cut off and replaced with the power from the external supply? If not, does anyone know of any suitable cables or clear diy instructions for someone with little knowledge but reasonable DIY skills?

Just to note that the Itemaudio site says the power input for the Microtik cable is 2.1mm whereas the manufacturer's site says 1.1mm:

RouterBoard.com : 5VUSB



I figure that it shouldn't cost much more than a hub to build this and it should solve the Joggler issue more neatly than a powered hub and it just might improve the sound in the hifi system.


Thanks for any help.

 

[dan1502]

Ooops, I think I have posted this in the wrong section. Mods, would you please move it somewhere more appropriate?

 

[ajst2duk]

I made up your a few 5V supplies now using a circuit published by John Swenson (uses a Hammond 10mh 159ZJ and an LT1084 5v reg) and use a "Y" cable setup ( type B connector splits to two type A one for data and one for power) and used these on audiophileo with great results.

 

[dan1502]

I would need female type A to male type A and power. The power supply I intend using is the same as the one for £19.99 on the Itemaudio site but sourced for about 1/3 - 1/2 of the price. It's a 5V, 1A wall wart.

 

[tofurky]

i bought a couple of those mikrotik 5v injectors. the power/ground is connected to both the input/output of the cable, so if you want to isolate it you would need to lift a couple pins on the usb connector. it's not too difficult to do with a small flathead screwdriver.

i had mixed results injecting power to a dac; on my laptop, it worked OK, but on another system, the dac wasn't detected. it wouldn't detect even with ground connected.
-matt

 

[dan1502]

Thanks, that's as I suspected. It was articles such as this one which made me think this might be more complicated than I first thought:

Continuing pursuit of power supply improvements and improved Dac performance.

And these were the power supplies I was thinking of:

http://www.farnell.com/datasheets/1513727.pdf

but used in conjunction with a Schaffner mains filter (which I already use with various other components).

I'm not sure whether, although linear, that power supply will be any good though as they're only about £8 or so for the model I would use (5V, 1A).

 

[liquidsmoke]

Did you ever arrive at a solution?

 

[Max Headroom]

ADUM4160 USB Isolator
I ordered one of these recently for T&M purposes....AUD$26.00 including postage.
It hasn't arrived yet so I don't know how well it works.
This board isolates USB data lines, isolates earths, and allows injection of +5V to power the peripheral device, ie USB soundcard.

Dan.