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Old 10th September 2012, 09:26 PM   #2801
PelPix is offline PelPix  United States
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Quote:
Originally Posted by Rullknufs View Post
My O2+Odac did the same yesterday, but then my phone was ~10cm from the device. If I have the phone if my left pocket and the amp on the desktop on my right I have never heard it pick up any noise.
I have, but my phone's radio is super powerful. I've heard it pick up noise before I get a text when my phone is on the counter on the other side of the room.

The position of the potentiometer controls the panning of the RFI for some reason. If it's at 12 o clock, the RFI comes out of both headphone channels. If the volume is all the way down, it comes out the left, and the right if it's all the way up.
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Old 10th September 2012, 09:39 PM   #2802
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Quote:
Originally Posted by 6L6 View Post
Did you ground the case?

Click the image to open in full size.
I did. But then I'm using the USB input of the ODAC and not the 3.5mm of the O2...
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Old 10th September 2012, 10:20 PM   #2803
agdr is offline agdr  United States
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Originally Posted by Rullknufs View Post
I did. But then I'm using the USB input of the ODAC and not the 3.5mm of the O2...
As a test, when the cell phone noise is happening, pull out the USB cable from the ODAC (just the O2 left powered up) and see if the noise goes away. If it does go away, plug the USB cable back into the ODAC and this time unplug the USB cable end at the PC and see if the noise is still gone.

If unplugging the ODAC end kills the noise, but unplugging the PC end doesn't, then using a USB cable with ferrites on each end would be worth a try. Something like this:

http://www.trianglecables.com/usb-ca...es-chokes.html

Last edited by agdr; 10th September 2012 at 10:25 PM.
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Old 11th September 2012, 10:27 AM   #2804
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Originally Posted by agdr View Post
As a test, when the cell phone noise is happening, pull out the USB cable from the ODAC (just the O2 left powered up) and see if the noise goes away. If it does go away, plug the USB cable back into the ODAC and this time unplug the USB cable end at the PC and see if the noise is still gone.

If unplugging the ODAC end kills the noise, but unplugging the PC end doesn't, then using a USB cable with ferrites on each end would be worth a try. Something like this:

USB 2.0 Cables with Dual Ferrites AM to BM AF Mini 5 Pin Micro B
I have the same thing happen with my cellphone when it synchronizes with the cell tower or receives txt/calls it affects the O2 only. It's rather infrequent and not and very loud so it doesn't bother me. Adjusting the O2 volume doesn't change the volume which suggests to me the interference is being received somewhere in the amplification stage of the O2?
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Old 11th September 2012, 02:36 PM   #2805
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Originally Posted by Jaketastic View Post
Adjusting the O2 volume doesn't change the volume which suggests to me the interference is being received somewhere in the amplification stage of the O2?
Could be. Most likely one of the external cables is acting like an antenna to conduct the cell phone EMI into the (O2) box, either via a shield on a shielded cable or common mode noise on a twisted pair.

To see if it is the power cable, if your O2 has batteries, unplug the power cable when you are getting cell phone noise and see if the noise is still there on batteries. I wanted to try that above for the USB cable test, but the ODAC has replaced the batteries.

To see if it is the audio source cable, disconnect the audio cable at the O2 end while the cell phone interference is happening. If the noise goes away, plug that end back in and unplug the other end going into the source. You will get some noise with that cable unplugged, since is has no signal and isn't grounded, but the bulk of the cell phone noise would still be there if that cable is the issue.

Also possible the cell phone EMI is getting into the box just via the tiny gaps around the front and rear panel edges, but that is a different deal. Where is RocketScientist??? He is a lot better at this stuff than me.
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Old 11th September 2012, 10:00 PM   #2806
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I've disconnected the source input cable from the O2 although mine isn't connected up to batteries but I did notice that the caps hold charge for about a second if I disconnect the power source which provides me with enough of a window to test in. My cellphone transmits on frequencies of 900 and 1800mhz which gives a wavelength of 0.33 and 0.16 of a meter or 33 and 16cm. I don't believe a cell phone would be shielded against transmissions outside it's frequency bands. I'm unsure of the specifics but I do believe that the receiving aerial needs to be a multiple of the wavelength of the transmitted frequency.
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Old 12th September 2012, 05:34 PM   #2807
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I lent my O2+Odac to a friend and now I only have my Asus Xonar Essence STX. It's sad, because the Objective combo is much better than the STX. Hopefully I'll get it back tomorrow Now I just need to get rid of my Xonar STX, because I'll never use it again when I get my Objective combo back.
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Old 12th September 2012, 05:44 PM   #2808
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Originally Posted by Rullknufs View Post
I lent my O2+Odac to a friend and now I only have my Asus Xonar Essence STX. It's sad, because the Objective combo is much better than the STX. Hopefully I'll get it back tomorrow Now I just need to get rid of my Xonar STX, because I'll never use it again when I get my Objective combo back.
It's a hard life.
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Old 12th September 2012, 07:52 PM   #2809
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Originally Posted by lorriman View Post
It's a hard life.
Yes... What used to be great has now become "bad". What a hard life...
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Old 13th September 2012, 07:11 PM   #2810
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Originally Posted by Rullknufs View Post
I lent my O2+Odac to a friend and now I only have my Asus Xonar Essence STX. It's sad, because the Objective combo is much better than the STX. Hopefully I'll get it back tomorrow Now I just need to get rid of my Xonar STX, because I'll never use it again when I get my Objective combo back.
Really? b/c that card has ridiculously good specs. . .
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