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Old 25th July 2012, 03:43 PM   #2681
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Default power O2 from USB +5v mod

I've just made a portable mod to power O2 from USB +5v .
DC-DC Photo Gallery by objective3 at pbase.com
Using MEA1D0512DC 9$ 5V to +-12V bipolar DC-DC converter with low noise LC filter 47uH + 1uF on each channel.
This 1W DC-DC converter is able to supply power to O2 from ODAC mini USB line so both work simultaneously from USB power only.
There two options
1) put DC-DC PCB inside 9V battery case and use battery connectors. In this case to use it with battery you need you need to remove DC-DC
2) insert is as a PCB addon as shown at the second half of slides. In this case you can use rechargeable battary and even charge them with DC-DC power (1W = 42mA at +12V and 42mA at -12V). With D-150 250 Ohm Headphones Amp consumes 20-25 mA so you have spare 20 mA to charge battery even while listening.

how to move ODAC from batteries space see ODAC + O2 combo portable mod Photo Gallery by objective3 at pbase.com
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Old 25th July 2012, 03:44 PM   #2682
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Default ODAC + O2 combo portable mod

As currently there are plenty of mobile phones/tablets
xda-developers - View Single Post - [Q] USB sound card on Android? and Apple devices supporting external DAC output it makes sense to issue a version of ODAC + O2 portable combo that can work from 9-8.4V batteries as original O2 design. I just did this mod using JDS Labs combo. The only additional effort is drilling one hole in O2 PCB (on unused spot) and moving USB hole on the back plate. Please see attachments. I think it will be useful for current and future ODAC + O2 combo users as well opens combo to new use cases.
so here it is ODAC + O2 combo portable mod Photo Gallery by objective3 at pbase.com
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Old 28th July 2012, 03:01 PM   #2683
VJK is offline VJK
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Need help - I built a completely new O2 board ground up instead of de-bugging my old board which apparently developed a issue with Q2. The new board works perfect with input from various sources except for ODAC !! My ODAC has an output jack soldered and I checked that it works fine. But when I connect the wires ODAC + O2 I hear nothing on the phones . I triple checked the connections and they look OK visually as well as on the the DMM, any clues ? I did not cut the traces on O2 as I intend to use the input jack. I have routed the wires through the empty POT holes on O2.
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Old 28th July 2012, 07:23 PM   #2684
VJK is offline VJK
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The interesting bit is that if I connect the ODAC and the O2 Via a stereo cable with jacks, it works ! 8-/ no clue why the direct wires connecting the two doesn't work.
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Old 28th July 2012, 08:11 PM   #2685
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You still need to cut the traces on the O2.

Try plugging a spare 3.5mm jack into the input socket - this will lift the shorting links in the O2 input socket and let the ODAC signal through.
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Old 28th July 2012, 10:25 PM   #2686
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Quote:
Originally Posted by chouck View Post
I've just made a portable mod to power O2 from USB +5v .
DC-DC Photo Gallery by objective3 at pbase.com
Using MEA1D0512DC 9$ 5V to +-12V bipolar DC-DC converter with low noise LC filter 47uH + 1uF on each channel.
This 1W DC-DC converter is able to supply power to O2 from ODAC mini USB line so both work simultaneously from USB power only.
There two options
1) put DC-DC PCB inside 9V battery case and use battery connectors. In this case to use it with battery you need you need to remove DC-DC
2) insert is as a PCB addon as shown at the second half of slides. In this case you can use rechargeable battary and even charge them with DC-DC power (1W = 42mA at +12V and 42mA at -12V). With D-150 250 Ohm Headphones Amp consumes 20-25 mA so you have spare 20 mA to charge battery even while listening.

how to move ODAC from batteries space see ODAC + O2 combo portable mod Photo Gallery by objective3 at pbase.com
This is seriously exciting. The PSU is a brick. Since I would be looking to mostly use the O2+Odac with my laptop this is a marvellous development.

I would like to implement this myself. However, not knowing much about electronics and seeing the response of RS and others to suggestions generally being negative (or at least suggesting significant changes) I would love to see some comments from the other experts here. Since there has been a notable lack of response to this, perhaps it needs a new thread?
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Old 28th July 2012, 10:36 PM   #2687
swalter is offline swalter  Switzerland
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Quote:
Originally Posted by VJK View Post
The interesting bit is that if I connect the ODAC and the O2 Via a stereo cable with jacks, it works ! 8-/ no clue why the direct wires connecting the two doesn't work.
Quote:
Originally Posted by digitfan View Post
You still need to cut the traces on the O2.

Try plugging a spare 3.5mm jack into the input socket - this will lift the shorting links in the O2 input socket and let the ODAC signal through.

Hi, as digitfan pointed out, as long as the traces are not cut your input signal from the ODAC will be routed directly to ground on the O2. Your input socket will work normally as well after cutting the traces, so no worries.

Stefan
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Old 28th July 2012, 10:53 PM   #2688
VJK is offline VJK
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Digitfan, Walter Thank you very much. I just tried with a 3.5mm jack in the input socket of the O2 , that still doesn't work. I suppose cutting the traces is a must then ?
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Old 28th July 2012, 11:07 PM   #2689
VJK is offline VJK
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Update : Yes, the traces needed to be cut ! inserting the empty jack did not work for me unfortunately. Walter, Dititfan : Thank you both very much. ODAC and other sources work . Thanks again.
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Old 31st July 2012, 04:15 AM   #2690
6L6 is offline 6L6  United States
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I made a build log when I built my O2, here is a link if you would like to see it -

Building the O2 Headphone Amp

Thanks!
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