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Old 13th May 2013, 06:17 PM   #3291
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Yes.
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Old 13th May 2013, 06:23 PM   #3292
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Still looking into the white noise I've been hearing with the ODAC and I have some interesting findings: the ODAC generates noise, even when disconnected from power. With the ODAC out of the case, isolated mechanically and electrically (except via the LOD, obviously), I can hear white noise on the amplified output when the USB cable is plugged into the ODAC and not plugged into the computer. Furthermore, if I plug the usb cable into the ODAC while listening, I can detect a short delay and a small thump before the noise starts, indicating that some circuitry on the ODAC board is being activated via the voltage present on the unplugged USB cable.
I've heard that the circuit and pcb layout for the ODAC have been maed public - can anyone direct me to it? I'd like to see if I can figure out what's going on here.

thanks!
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Old 13th May 2013, 08:03 PM   #3293
agdr is offline agdr  United States
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Quote:
Originally Posted by smudgeface View Post
I've heard that the circuit and pcb layout for the ODAC have been maed public - can anyone direct me to it? I'd like to see if I can figure out what's going on here.
Right here:

http://www.yoyodyneconsulting.ca/dow...AC-release.pdf (opens PDF)

from George's site here

Yoyodyne Consulting/Audio Hardware/ODAC

and more info on NwAvGuy's blog here

http://nwavguy.blogspot.com/2012/04/odac-released.html
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Old 13th May 2013, 10:53 PM   #3294
Davey is online now Davey  United States
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Quote:
Originally Posted by smudgeface View Post
Still looking into the white noise I've been hearing with the ODAC and I have some interesting findings: the ODAC generates noise, even when disconnected from power. With the ODAC out of the case, isolated mechanically and electrically (except via the LOD, obviously), I can hear white noise on the amplified output when the USB cable is plugged into the ODAC and not plugged into the computer. Furthermore, if I plug the usb cable into the ODAC while listening, I can detect a short delay and a small thump before the noise starts, indicating that some circuitry on the ODAC board is being activated via the voltage present on the unplugged USB cable.
I've heard that the circuit and pcb layout for the ODAC have been maed public - can anyone direct me to it? I'd like to see if I can figure out what's going on here.

thanks!
You either have a defective ODAC and/or your testing scenario is flawed in some way. Or maybe an incorrect interface to your O2.

My ODAC is dead quiet (measurable and audibly) with (powered or un-powered) USB cable attached, or without USB cable attached. Only in the case where you powered the ODAC but did not have serial data present do the outputs show some noise. (That configuration is not easily possible to set up.)

Cheers,

Dave.

Last edited by Davey; 13th May 2013 at 10:58 PM.
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Old 13th May 2013, 10:58 PM   #3295
billyk is offline billyk  United States
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The same here, I have an ODAC in the same case as a B1 and a pair of Amp-Camp amps and it is completely silent, full volume, ear to the speaker, ODAC powered or not.
Hope you can find it (the noise), it is a nice sounding DAC
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Old 18th May 2013, 05:28 AM   #3296
mah is offline mah  Australia
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Default O2 Batteries

Would 9V 500mAh batteries be suitable for the O2?

e.g. 2 PCS 9V 9 Voltage 500mAh NI MH Rechargeable Battery Batteries 3 Years Warranty | eBay
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Old 18th May 2013, 09:53 PM   #3297
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Does anyone have a step-by-step guide for modding an O2+ODAC to run off just the 5V USB input? I saw that someone had done it but the process wasn't particularly clear for an electronics newcomer. I don't really run my headphones at a high volume anyway so it'd be useful not to have to lug around the charging brick.
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Old 20th May 2013, 05:30 AM   #3298
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Quote:
Originally Posted by mah View Post
RS reported unused "no name" Chinese batteries exploding on the workbench. If you want, Tenergy also offers 9V in 500mAh ver. http://www.amazon.com/Combo-Tenergy-...ews/B009MA8SAI
To reduce the chg. time you can reduce R1,R2 to 100R or 120R (same wattage) from the original 220R for 9V 500mAh batt.
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Old 20th May 2013, 05:36 AM   #3299
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Quote:
Originally Posted by generalguy View Post
Does anyone have a step-by-step guide for modding an O2+ODAC to run off just the 5V USB input? I saw that someone had done it but the process wasn't particularly clear for an electronics newcomer. I don't really run my headphones at a high volume anyway so it'd be useful not to have to lug around the charging brick.
Don't want to discourage your DIY skills but if you are new to electronics stick with the original RS design as 5V from USB involves SMPS ckts using SMD components.
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Old 22nd May 2013, 04:17 PM   #3300
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Hi all, I recently built an O2 and have been enjoying it greatly. However, since I bumped up the gain on my phono preamp it's been distorting the sound pretty badly and seems to be overloaded. It sounds fine connected to a CD player.

Is there a good way to attenuate the signal so I can keep my phono preamp at 65DB of gain?
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