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.
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-cables-with-dual-two-ferrites-chokes.html
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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?
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.
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.
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.
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.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
It's a hard life.
It's a hard life.
Yes... What used to be great has now become "bad". What a hard life...
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
Really? b/c that card has ridiculously good specs. . .
The cellphone adjusts its output depending on exactly what it is doing, but more importantly, depending on the location of the basestation mast. If the mast is far away or is out of line-of-sight the cellphone will need to use more power to be heard, but if you're standing in the open close to the mast the phone will reduce its output (as will the mast when talking to your phone). This is a feedback (reporting) operation of increasing sophistication in modern systems dependent on the level of received signal at both ends. Modern basestations point the signal at the phone.
A receiving antenna works best (as a generalisation) when a fraction or multiple of the wavelength, but it is not absolutely necessary for it to be a fraction or multiple of the wavelength to receive (or transmit).
A cellphone by its nature is designed not to respond to (is shielded or otherwise protected against) frequencies other than the tuned frequency, otherwise there would be problems with receiving unwanted signals, since in most modern environments there is a plethora of potentially interfering signals.
Very loud switch on transient
Just thought I'd post to help anyone else with a similar problem - I had a very loud switch on transient. All tests were ok, voltages, resistances ok. It sounded fine but there was a very very loud switch on transient. I narrowed it down to Q1. Replacing that solved the problem.
Hope this helps...
Cheers,
Andy
Just thought I'd post to help anyone else with a similar problem - I had a very loud switch on transient. All tests were ok, voltages, resistances ok. It sounded fine but there was a very very loud switch on transient. I narrowed it down to Q1. Replacing that solved the problem.
Hope this helps...
Cheers,
Andy
Hello,
I received my O2 from JDS Labs a few days ago, and I would now like to change the gain settings. 2.5x is plenty for my LCD-2.2's from all my sources, and I'd like to have a 1x setting for IEM's. So I would like to change the 6.5x setting to 1x gain. Earlier in this thread somebody explained which resistors to clip to change the 2.5x to unity gain, but I want to keep the 2.5x and change the 6.5x to unity. Could anyone help?
I received my O2 from JDS Labs a few days ago, and I would now like to change the gain settings. 2.5x is plenty for my LCD-2.2's from all my sources, and I'd like to have a 1x setting for IEM's. So I would like to change the 6.5x setting to 1x gain. Earlier in this thread somebody explained which resistors to clip to change the 2.5x to unity gain, but I want to keep the 2.5x and change the 6.5x to unity. Could anyone help?
Hello,
I have a major problem with a massive DC offset. I have about -5.8V on the pot, U1 ( pin1 -5.81V, pin8 -6.6V), Also on the gain switch and gain resistors, but the resitors near the input (r3,7,14,20) are fine. Output is fine and U3+U4 also fine.
I've already double checked the TS section and all measurments are fine except D3 and D4 are 0.4V apart (d4 is lower) when powered on but within spec (0.1V) when off. I do have a working unit (o2) and i've compared the regulators and mosfets volatges and they're almost identical when power on.
*I don't detect any solder bridges or any of the sort.
This issue manifests as the volume control not working, only when i turn it all they way i hear the faintest audio signal.
Please advice, and If it's been discussed already please let me know roughly when i should start searching.
I have a major problem with a massive DC offset. I have about -5.8V on the pot, U1 ( pin1 -5.81V, pin8 -6.6V), Also on the gain switch and gain resistors, but the resitors near the input (r3,7,14,20) are fine. Output is fine and U3+U4 also fine.
I've already double checked the TS section and all measurments are fine except D3 and D4 are 0.4V apart (d4 is lower) when powered on but within spec (0.1V) when off. I do have a working unit (o2) and i've compared the regulators and mosfets volatges and they're almost identical when power on.
*I don't detect any solder bridges or any of the sort.
This issue manifests as the volume control not working, only when i turn it all they way i hear the faintest audio signal.
Please advice, and If it's been discussed already please let me know roughly when i should start searching.
Hello,
has anyone driven the O2 with an aikido preamp line stage, especially with 6sn7, or the O2 inputs will be overloaded?
The idea is that I would like to add a robust and capable to drive low impedance headphones amp module in my existing tube preamp, without getting involved in a "real" and time consuming diy project. My other choice will be the class A JLH amplifier, but it definitely needs some more work...
has anyone driven the O2 with an aikido preamp line stage, especially with 6sn7, or the O2 inputs will be overloaded?
The idea is that I would like to add a robust and capable to drive low impedance headphones amp module in my existing tube preamp, without getting involved in a "real" and time consuming diy project
. My other choice will be the class A JLH amplifier, but it definitely needs some more work...Aikido with 6SN7 at output stage can drive 300 ohm phones direct, I use with HD580.
If you have lower impedance phones, best way is to build output buffer on IRF510 or similar, or on two LM317 (see 24V Aikido).
Next option - build unity gain buffer on opamp (maybe similar like O2 output)
If you already have O2, you can try to remove gain stage opamp and send input signal direct to pot. In this case you use buffer only and not overdrive it.
Building O2 only for driving with Aikido is waste of time and money, better build one of simple buffers on protoboard, it is easy and direct what you need.
If you have lower impedance phones, best way is to build output buffer on IRF510 or similar, or on two LM317 (see 24V Aikido).
Next option - build unity gain buffer on opamp (maybe similar like O2 output)
If you already have O2, you can try to remove gain stage opamp and send input signal direct to pot. In this case you use buffer only and not overdrive it.
Building O2 only for driving with Aikido is waste of time and money, better build one of simple buffers on protoboard, it is easy and direct what you need.