# Convert Optical to USB



## Dookky

As the title suggests I am looking for a way to convert an optical signal coming from my mac mini into a usb signal to go into my d2+ boa. Now I know I should I have just bought a d4 or something WITH optical input but I wasn't aware of just how important isolation was when I bout it. This thread is in DIY because I haven't seen anything to do this. I have seen a whole bunch of things to convert usb to optical but that is NOT what I am after. So, I am now trying to gather as much information as possible to help me get started.
   
  I am looking for any information anyone has on such a project. Such as,
  Encoding of the Optical Signal coming from the mac mini
  USB encoding
  Hardware that should be used (power supplies, IC's, etc)
   
  I know I can get all of this information on the web, which is what I plan to do, but I thought it would be fun to put this up on the board and see if anyone would like to help. Also, if this has already been done before please point me in that direction.
   
  THANKS EVERYONE!
   
  Oh, and if this turns out to be a DIY project I'll post some updates in this thread, if anyone really cares.


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## Dookky

Hah, apparently I didn't look hard enough...
   
  http://industrialcomponent.com/opticis/m21xx.html
   
  if anyone cares, not the same thing but will serve the same purpose


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## FallenAngel

The short answer is converting S/PDIF to USB isn't possible (well, anything possible if you try hard enough, though generally this isn't feasible).


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## Juaquin

Quote: 





dookky said:


> Hah, apparently I didn't look hard enough...
> 
> http://industrialcomponent.com/opticis/m21xx.html
> 
> if anyone cares, not the same thing but will serve the same purpose


 

 Incredibly expensive, too. What's wrong with your normal USB ports? I doubt "isolation" of a digital signal is going to improve your sound quality enough to justify dropping $200+, but that's just my opinion.


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## mugdecoffee

I think you could make a similar cable without the optical conversion by replacing the USB power rails with an external supply.  So, the two data lines go from USB to USB and the output USB is powered from an external 5V.


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## FallenAngel

You'll still need ground in that cable.


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## Dookky

Thanks for all the posts! I've been thinking about why I would need to isolate a digital signal and it just doesn't seem reasonable as well. However I was concerned about the 5V rail coming from the USB. This has also got me thinking about my d2+ and it's power supply. From what I've read, it sounds like the unit should be supplied by its internal battery, however I have always had my unit connected to my pc (or mac) usb, and I have never had to charge the battery. So I'm curious as to how the amp is supplied power. Is the amp getting power from the usb or the battery? From my thinking, if the amp is getting power from the usb it might be a good idea to have a separate 5V supply or have the USB 5V go through a regulator or something. However if the battery is being used (but never being drained) then I would think it's doing its own regulation of the rail, and I am merely being paranoid over the matter. Maybe I should ask ibasso? again thanks to everyone for the great comments!


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## FallenAngel

If you haven't recharged your battery, it's obviously running off USB.  Do consider something though, are you sure worrying about some external 5V PSU is really what you should be trying to upgrade in a small portable Amp/DAC combo unit?


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