glunteer
100+ Head-Fier
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- Sep 15, 2012
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So... which would correct voltage and current for the ODAC?
So... which would correct voltage and current for the ODAC?
USB standard - 5v and 500mA. But it's also important that the power will be noise-free.
but the computer does not supply 500mA, right?
USB 2.0 port does provide 500mA, USB 3.0 port can give 1000mA.
I hate to say this but i have expereinced differences in audio playback quality on the same pc but different USB ports,
Once you get it right its pretty good...
Alex
Sometimes the simplest chain is the best.
If you are thinking desktop and not portable, take a look at this one that I came up with:
https://drive.google.com/folderview?id=0B67cJELZW-i8VmhVNk5PODNtZnc&usp=sharing 80mm x 160mm PCB -> latest date
All DIY that uses 3 of the NJM4556AL (SIP inline version of the NJM45556 instead of the DIP version, but same internals) in parallel on each channel for a total of 320mA usable (after quiescent chip draw) output per channel. Has +/-16Vdc rails (in one position, +/-7Vdc in the other switch position) for a 14.5Vdc maximum swing vs. the O2's 10Vdc max (10.5V rms vs. 7V rms with the O2). So it will drive cans that need more voltage swing and/or a lot more current. 4 gain positions vs. 2, 3.5mm and 1/4" out, RCA and 3.5mm input, pre-amp output, clipping indicator, 0.5R balancing resistors instead of 1R, 2 sets of voltage regulators (pre and final low noise LDO), output relay to prevent thumps, 1K pot for low Johnson noise and some other goodies.
I'm not selling anything. It is all DIY. The PC board can be made by sending the Gerber file in the link off to a board house like Seeed Studio (4 layer, 160mm x 80mm). The build involves some surface mount parts, 1206 sized resistors and caps along with the through hole, so a little more involved - and twice as many parts - as the O2. But similar design with the pot and coupling caps in the middle and gain stage in front. So far the consensus has been (big discussion in another forum) that it is different enough to be a separate design, not a O2 derivative. No batteries, no power management circuit, not portable.
It uses the larger (than the O2) B4-080BL case, or can use 2 boards end-to-end in a longer B4-160BL case, which then easily holds an ODAC on the back board. The back board just has the PSU section populated in the 2 board option, while the front board has everything but the PSU populated. In one of the folders in the link there are CAD files for the front and back panels which can be sent off to outfits like Proto Panel (the one I used) or Front Panel Express. The panel hole measurements are all also in a spreadsheet there to self-drill the panels that come with the case. The BOM lists all the Mouser numbers and some cross references to Digikey, Farnell, Allied, and others.