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O2 AMP + ODAC - Page 111

post #1651 of 3410

So... which would correct voltage and current for the ODAC?

post #1652 of 3410
Quote:
Originally Posted by glunteer View Post

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.

post #1653 of 3410
Quote:
Originally Posted by BenF View Post


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?

post #1654 of 3410
Quote:
Originally Posted by glunteer View Post


but the computer does not supply 500mA, right?


USB 2.0 port does provide 500mA, USB 3.0 port can give 1000mA.

post #1655 of 3410
Quote:
Originally Posted by BenF View Post


USB 2.0 port does provide 500mA, USB 3.0 port can give 1000mA.

Thanks benf smily_headphones1.gif
post #1656 of 3410

Thanks for the help on the USB hub issue. It's really always impressive to me how with the right headphone and amp (O2) I can detect issue with my setup when things are "off".

My idea is that I had my powered USB hub attached to a massive MOV-based home theater surge protector. Maybe some type of garbage/interference was getting through and messing with things. I never heard this issue with my Micro Amp or the old Magni at all. Maybe the O2+Modi is that super duper revealing? biggrin.gif I did have TONS of stuff attached to the surge protector.

 

Strangely I only heard this with my Vmoda M80 and DJ100. Basically inaudible with my HD-650 and Q701. It seems it's only noticeable with closed bassy headphones that have forward low mids and are portable.

 

I also don't use USB cables with ferrite beads. Guess i'll try some again. I don't think it's really noise, but something weird about my surge protector. It could be a poor quality wall wart on the USB hub.

 

I'm sure when I connect it straight to the wall it's OK.

 

Strangely i've always had weird/random issue with every DAC i've owned when attaching it to my desktop USB ports. Lots of static/popping etc. It's especially bad on my laptop. Mostly occurs when scrolling in Windows and it was gone with a powered USB hub.

 

Just kind of confusing why it only happens on the O2.

 

I think I might buy a USB 3.0 hub and some short USB cables with ferrite beads.

 

BTW O2 now sounds good with everything I have now. It reminds me of my Headroom Micro really. I no longer have the ODAC, but Modi.

post #1657 of 3410

Sometimes the simplest chain is the best.

 

I have heard or experienced popping and ticking while listening to music via a pc and a music player..ie software.

 

In most cases its the pc and or sound driver interaction with the OS etc. Ususally it can be fixed by having a more powerful pc, better drivers, and adjusting the buffers on the system usually in the software player.

 

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

post #1658 of 3410
Quote:
Originally Posted by adydula View Post

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

I have experienced very noticeable differences between one particular computer's usb 3.0 and usb 2.0 ports. Undoubtedly there was some problem with the 3.0 drivers, but it sounded horrid.

post #1659 of 3410

I think that my objectivity is getting cross pollinated over time with my subjectivity!

A.

post #1660 of 3410
Quote:
Originally Posted by adydula View Post

Sometimes the simplest chain is the best.

 

Totally agree. I also try to make sure my USB cables are as short as possible. It can't hurt really.

I replaced my USB cables with ferrite core version (probably not needed).

 

I switched the USB hubs wall wart to a power strip with no surge protection but that didn't help at all. Not sure why. I guess maybe the fault is the powered hub or having it use two USB cables.

 

I get an almost identical sounding problem when I connect my amps to a surge protector (mov based).

 

Right now I have my DACs connected right to my PC and it seems fine. Weird.

 

Whenever I use a MOV based surge protector it sounds like I'm getting extra distortion. It's barely audible but that's what it sounds like. It makes my HD-650 sound even more muffled.

 

It sounds similar to double amping two portable devices. Like Clip+ to E11 or something, but almost worse. It would actually sound OK on some headphones but horrible on others.

post #1661 of 3410
Quote:
Originally Posted by agdr View Post
 

 

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.  smile.gif

 

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.

 

I would buy a complete unit w/ integrated ODAC in an instant if it was available, I don't trust my soldering skills heh. How long have you been testing it?

 

Does this version increase the requirements for lower end headphones?

post #1662 of 3410

I was actually thinking of building this but the pc boards have a minumum order and it gets pricey...unless u can get a bunch of people to help finance etc..

 

Alex

post #1663 of 3410
You can buy the PCB's from JDS Labs for $6. The ODAC + O2 can be built for has low as $180 (even less...) If you pay your cards properly. I finished building one last month (and it's even possible to keep the batteries....).
Edited by Ashade - 9/26/13 at 5:39pm
post #1664 of 3410

Anybody around owns the Epiphany Acoustics UK version of this combo? (DAC+AMP) in the same box ? 

 I have bought one a month ago and can´t figure out which are the low/high gain settings without opening it .

The manufacturer told me they use 1X/5X as default, but another user here told me his unit was 2.5X/6.5X so 

I´m a little confused .

Thanks.

post #1665 of 3410

2 .5x/6.5x is the stock design for the O2, but the guy provided instructions to do other configurations. If they say it is 1x/5x... they are the builders you know? I can tell you that I don't pass of 10 or 11 o´clock (35% to 45% of the max volumen) with the Q701 and 2.5x gain selected.

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