In preparation for my incoming CEntrance HifiM8, I decided to try my hand at making a Micro USB B OTG to USB B cable so that I can use my Galaxy Note II as my transport.  
 
It turned out alright (confirmed to work with my Note II and my Nuforce HDP) so I decided to post this tutorial for anyone with an Android device that is USB OTG capable for use with outboard DACs.
 
Please forgive me for not having more pictures - I always forget to document things until I am half way through.
 
DISCLAIMER:  This info is only for the connectors that I used.  I am also human and might have mislabeled something.  Always verify my info with what you know and find out about the connectors that you use.  
 
1.  Obtain Micro USB B connector.  I got mine on ebay.  While this listing isn't the one I bought (can't find the original), these look like they should work: http://www.ebay.com/itm/DIY-Micro-USB-Type-B-Male-5Pin-four-piece-assembly-Connector-black-color-10pcs-/160922939469?pt=US_Cell_Phone_PDA_Cables_Adapters&hash=item2577c1304d
 
2.  Obtain USB B connector.  I harvested mine from a monoprice cable (use heatgun to soften molded cover and remove with pliers and a cutter).  You can get them at any electronics shop like Mouser or if you want a pretty gold plated one, Doublehelixcables had them at last check.
 
3.  Link pin 4 and 5 on the Micro USB B connector.  This short will let the Android device recognize the cable as an OTG cable and treat whatever is on the other end accordingly.

The picture above shows the pins (4 and 5 linked with a small jumper of wire) on the connector I used (not guaranteed to match, please check whatever documentation you get for your connector or check for continuity using a multimeter).  The red arrows are pointing to the three pads on top, the blue indicates the that the other two pads are on the bottom.  They alternate top and bottom.
 

Another shot showing the jumper and a better idea of where the bottom two pins are.
 
4. Carefully plan out the length of your wires, as there isn't a lot of room or margin for error.  The pads for soldering are very close together so also be careful about how much solder you use and how thick a wire you use.  You can see how 26awg fits from my pictures (might be as large as I would go).
 
5. I started the wiring from the USB B side since it easier to anchor and needed the most thought for placement of wire.  I chose to have the wires come out of the top based on the layout of the M8.

Here is the USB B with the wires attached already at their respective spots.  Again red indicates on top, blue on bottom.  
 
6.  Depending on the USB B connector that you get, you will have to cut down the shield to keep the cable as low profile as possible.  I had some tin snips that I used to cut mine down to size.  
 
7.  At this point, you could braid your wires, but for me, for such a short cable with such small connecting points, I figured it would be more trouble than it is worth to do so.  A simple twist should work fine.
 
8.  Here is a picture showing everything wired up but with a couple labels added:

(sorry, didn't take a picture of the underside, but it should be straight forward at this point)
 
9.  At this point, recheck pinouts and continuity to make sure you have the pins linked to the right pins on the other connector.  Make sure there are shorts, as well.
 
10.  If everything tests ok on the multimeter, see if it works with your rig.  
 
11.  If everything works ok, finish the bodies of your connectors with something like epoxy putty or my favorite, Sugru.  Hot glue could even work if you want something see through.
 
12.  Done:


 
 
Have fun!

Thank you for the guide. Much appreciated.

Awesome work. Just what I'm looking for, except I don't currently have the equipment(or skill probably) to make this. Hopefully someone will put some up for sale.

would it be easier/possible to get a stock cheap micro otg cable and re-terminate the other end to USB B?
 
I'm also on the CEntrance Hifi-M8 pre order list and I just bought an ibasso D42 which uses the same USB B connector.

wormsdriver said:

would it be easier/possible to get a stock cheap micro otg cable and re-terminate the other end to USB B?

I'm also on the CEntrance Hifi-M8 pre order list and I just bought an ibasso D42 which uses the same USB B connector.

Click to expand...

Yes. Very simple since the wires will most likely be color coded. Only 4 wires to deal with on that end.

so how will I know which wire goes where?
 
sorry to ask, maybe I shouldn't be messing with things I don't understand yet
 
...but hey, I would like to learn
 
 
 
 
Actually, the more I go through your tutorial, it's starting to make sense, maybe I'll try it that way instead, that way I know what goes where.

oh snap! i just read the Main Features on the ibasso website for the d42:
 
 
Main features:
- Dual Wolfson WM8740 DAC Chip 
- TI PCM2706 for USB signal input, provides I2S interface for decoding
- Works as a DAC+AMP Combo, a standalone AMP, or a standalone DAC (Line out function) 
- 2-Setting Gain Switch
- OPAMP rollable
- AMP section can be powered by either USB or 9V battery
- Measures 60*20*92mm, and weighs 102g
- Comes with 3.5 to 3.5 interconnect cable, pouch, USB cable, and OTG cable.

 

 
 
I still wanna make a better fitting/angled OTG cable, but this takes off the pressure of trying to rush it.

Here are two images that should help:


 
I am always an advocate of DIY when there is opportunity.  Happy to help if you give it a shot and run into questions.

Thanks a lot FraGGleR!
 
those last two images REALLY help understanding and simplifying things a great deal.
 
I'll need to practice on my soldering skills, but I'm looking forward to hopefully trying this out in the near future.

ok, here's my first attempt at this kinda thing.  It turned out to be pretty simple (thanks to the tutorial and pics!)
 
 
I ended up cannibalizing an existing otg cable I had and a cheap monoprice usb b cable. All I had was a hot glue gun for the time being so it'll have to do.
 

 
Here it is in action!

 

Quote:

wormsdriver said:

ok, here's my first attempt at this kinda thing.  It turned out to be pretty simple (thanks to the tutorial and pics!)
 
 
I ended up cannibalizing an existing otg cable I had and a cheap monoprice usb b cable. All I had was a hot glue gun for the time being so it'll have to do.
 
 
 
Here it is in action!

 
 
 

Click to expand...

Awesome.  I started off cannibalizing cables (and sometimes still do for connectors).  I'm glad it worked for you and doubly glad that you have confirmed the M8 works with USB Audio Recorder Pro. 
Hopefully by the time I get my M8, I will have figured out why USB ARP stopped working for me.

Quote:

fraggler said:

Here are two images that should help:

Click to expand...

 
 
Thanks

here's my second attempt at this DIY OTG Micro USB B cable to USB B.
 

 

 

 

 

 

 
I used shoe goo on the black one (only thing besides hot glue I had available).
 
the other is made with SPC OFC cable that came off a BTG-Audio Starlight iem cable, still unfinished till I get some Sugru!
 
 
Thanks for the tutorial [size=18.399999618530273px]FraGGleR[/size]!

Quote:

wormsdriver said:

here's my second attempt at this DIY OTG Micro USB B cable to USB B.

 
I used shoe goo on the black one (only thing besides hot glue I had available).

 
the other is made with SPC OFC cable that came off a BTG-Audio Starlight iem cable, still unfinished till I get some Sugru!
 
 
Thanks for the tutorial [size=18.399999618530273px]FraGGleR[/size]!

Click to expand...

Haha, I was going to ask what you used on the black one.  I found some black hot glue that I have been tempted to buy, but it is either crazy expensive for a single stick, or I get enough to last a lifetime.
 
Great job!
 
PS Are those harvested micro USB connectors?

Thanks!


I got a pack of ten micro usb connectors from eBay.