Help with Interference issue [resolved]
- Thread starter networkn
- Start date
Boy oh Boy how the plot has thickened!
Turns out that the problem IS being introduced at the source, if the source is considered the ODAC connected between the Source and the Crack Amp.
I did the reflow and then if anything the problem seemed worse (settled back to normal badness after a bit).
I can't hear anything I would consider abnormal (A bit of staticy type noise when I move the volume on the crack just whilst it's moving) when the ODAC isn't present, but then the sound isn't as good. If I plug the ODAC into the O2 Amp I have, I can't hear anything, so it seems to be some sort of weird compatibility between the ODAC and the Crack.
I apologise for the incorrect information, it's been a few months since I last worked on the issue, and my memory of the troubleshooting has obviously let me down.
Should I start a new thread to address the potential issue between the ODAC and the Crack or just continue?
Turns out that the problem IS being introduced at the source, if the source is considered the ODAC connected between the Source and the Crack Amp.
I did the reflow and then if anything the problem seemed worse (settled back to normal badness after a bit).
I can't hear anything I would consider abnormal (A bit of staticy type noise when I move the volume on the crack just whilst it's moving) when the ODAC isn't present, but then the sound isn't as good. If I plug the ODAC into the O2 Amp I have, I can't hear anything, so it seems to be some sort of weird compatibility between the ODAC and the Crack.
I apologise for the incorrect information, it's been a few months since I last worked on the issue, and my memory of the troubleshooting has obviously let me down.
Should I start a new thread to address the potential issue between the ODAC and the Crack or just continue?
How are you powering your ODAC?
You might want to try getting a USB cable with an external power supply, or if you aren't already, try using a laptop running on its battery.
Hi There!
Ok well, I plugged the ODAC into my laptop and it sounds AWESOME with the CRACK. No noise, nothing. Perfect. Seems there is an issue between the USB on my PC, the ODAC and the Crack. The ODAC guy asked:
"If the Crack amp uses two independent grounds for each channel (rare), perhaps ODAC's common ground creates issues within the Crack Amp"
Is this possible/Likely or is it really now a case of figuring out why my PC USB causes the problem when it doesn't happen with another AMP or even with no amp?
On the plus side, I think this means I made no mistakes whilst building the crack. My grandfather (RIP) would have been so proud. It was him that introduced me to Electronics when I was 8, and bought me my first DIY Electronics kit, with strings instead of solder.
I have been trying to find a place that makes very nice little metal plates (Plaques) I can have laser etched, my dedication of the amp to him, in case anyone knows of a place.
Ok well, I plugged the ODAC into my laptop and it sounds AWESOME with the CRACK. No noise, nothing. Perfect. Seems there is an issue between the USB on my PC, the ODAC and the Crack. The ODAC guy asked:
"If the Crack amp uses two independent grounds for each channel (rare), perhaps ODAC's common ground creates issues within the Crack Amp"
Is this possible/Likely or is it really now a case of figuring out why my PC USB causes the problem when it doesn't happen with another AMP or even with no amp?
On the plus side, I think this means I made no mistakes whilst building the crack. My grandfather (RIP) would have been so proud. It was him that introduced me to Electronics when I was 8, and bought me my first DIY Electronics kit, with strings instead of solder.
I have been trying to find a place that makes very nice little metal plates (Plaques) I can have laser etched, my dedication of the amp to him, in case anyone knows of a place.
Crack uses a common ground between the two channels. Since your laptop is quiet (presumably running on betteries or maybe a two prong power cord) and your PC is not (presuming your PC is plugged ito the wall) there may be a ground loop issue. Is the PC plugged into the same AC mains outlet as the Crack?
Doc B. said:
Hi There!
Sort of, My PC is plugged into a 4 Way Zap Catcher, and the Laptop was plugged into another 4 Way Zap Catcher, but eventually they end up in the same wall socket. The Laptop probably is quiet as much because it runs from battery even when plugged in as I understand it.
How do I tell what is not grounded? Is there an easy test? If the Crack wasn't grounded, what would happen? Would it's fuse blow? I have the 240v version.
PassionForSound
New member
networkn said:
Hopefully others will chime in and help here, but I think the issue is in your power supply to the computer and or the USB signal from the computer.
Can you try plugging the DAC and Crack and PC into the same power board and report on the results?
Loquah said:
I'll try this tomorrow as I got my new Bi-Frost and I am in Musical Bliss right now
Not sure if this helps, but plugging into the BiFrost from the the SPDIF also has a slight buzzing noise in the right hand ear. Sadly the base for my crack isn't assembled so moving it, is no easy feat.
Paul Joppa
Moderator
Just a note - ground currents (often called "ground loops") do not occur within a component, but rather between components. That's why they are so hard to trace ... :^)
What happens is there is an AC current in the ground side of the interconnect, and that current drops a tiny voltage because the ground wire has some resistance, and that voltage gets added to the signal.
You can start with the Crack no connected to anything, and the volume turned all the way down. If there is hum, it is within the Crack. (You can then turn the volume up, and detect whether there is electromagnetic interference noise - always good to eliminate other possible problems!)
Then connect the DAC to the Crack, with nothing else connected to the DAC. If you get a new hum/noise then the DAC is likely introducing a noise current into the interconnect ground wire. If the DAC has a two-prong plug you can try reversing it, sometimes this helps. You can also try running the power cables close together for as long a distance as possible, sometimes that helps.
If there is still no noise with the DAC connected to Crack, then connect the computer. The same comments as the above paragraph apply. The computer is likely connected to other line-powered devices such as a router or a printer, so you can try disconnecting them to further isolate the problem.
What happens is there is an AC current in the ground side of the interconnect, and that current drops a tiny voltage because the ground wire has some resistance, and that voltage gets added to the signal.
You can start with the Crack no connected to anything, and the volume turned all the way down. If there is hum, it is within the Crack. (You can then turn the volume up, and detect whether there is electromagnetic interference noise - always good to eliminate other possible problems!)
Then connect the DAC to the Crack, with nothing else connected to the DAC. If you get a new hum/noise then the DAC is likely introducing a noise current into the interconnect ground wire. If the DAC has a two-prong plug you can try reversing it, sometimes this helps. You can also try running the power cables close together for as long a distance as possible, sometimes that helps.
If there is still no noise with the DAC connected to Crack, then connect the computer. The same comments as the above paragraph apply. The computer is likely connected to other line-powered devices such as a router or a printer, so you can try disconnecting them to further isolate the problem.
Paul Joppa said:
Hi Paul
These are the facts as I understand them right now.
1) Amp with nothing connected - No unusual noise
2) DAC connected to Crack, but no USB Connected - No unusual noise
3) ODAC connected to USB on Desktop Computer, connected to Crack - Noisy
4) Bifrost connected to USB on Desktop, Connected to Crack - Noisy
5) ODAC/BiFrost Connected to Laptop via USB - No Noise
6) ODAC to Headphones directly, connected to PC or Laptop via USB - no Noise
7) BiFrost Connected via SPDIF to Crack - Slight noise - Not as bad as via USB
8) ODAC connected to PC via USB then Connected to O2 AMP - No Noise
9) ODAC Connected to Laptop via USB then Connected to O2 Amp - No Noise
10) Noise from 3 doesn't seem to change as I adjust the volume knob on the crack
11) Noise from 3 doesn't seem to change if I remove one of the RCA's or the other, or if I swap them around
12) Noise from 3 not affected by type of music playing, or sample rate etc.
13) Noise from 3 can be drowned out if the volume is loud enough (Music
14) The Music coming from the crack in 3 sounds Excellent, just the buzz in the background
15) Noise from 3 moves from right hand to left hand depending on how far the headphone is inserted into the jack.
I have tried to troubleshoot this as methodically as I can...
Paul Joppa
Moderator
Excellent data!
I'm going out of town so hopefully PB will pick up this thread, but you have pretty much confirmed (as I see it) that the noise comes from a ground current running from the desktop computer to the Crack ground, which is connected to the power line safety ground. (I assume the O2 has a two-prong power cord and is double insulated instead of being safety grounded.)
If I am right and you can use an optical interconnect to the DAC, that should solve it. That would break the ground current path.
I'm going out of town so hopefully PB will pick up this thread, but you have pretty much confirmed (as I see it) that the noise comes from a ground current running from the desktop computer to the Crack ground, which is connected to the power line safety ground. (I assume the O2 has a two-prong power cord and is double insulated instead of being safety grounded.)
If I am right and you can use an optical interconnect to the DAC, that should solve it. That would break the ground current path.
Yeah, this kind of thing isn't all that uncommon. You could also try a powered USB cable, though that may or may not solve your issue.
The optical connection is a very good option.
The optical connection is a very good option.
JamieMcC
New member
Sound similar to my experiences rerouting of cables and switching to optical interconnect for dac and pc sorted it out.
The hardest noise to trace was a intermittent buzz during the winter in the evenings it was driving me nuts coming and going and turned out to be a electric oil filled radiator in another room tripping in and out on its thermostat. I was running my internet signal through the houses power sockets at the time.
The hardest noise to trace was a intermittent buzz during the winter in the evenings it was driving me nuts coming and going and turned out to be a electric oil filled radiator in another room tripping in and out on its thermostat. I was running my internet signal through the houses power sockets at the time.
Ok Additional things I have tried today without any luck:
1) Put the Crack Amp, PC and Dac into the same powerboard. - Noisy
2) Unplugged al PC peripherals, Keyboards, mice, other USB devices (basically nothing except power and Coax SPDIF) - Noisy
3) Switched from SPDIF to Coax Spdif - Noisy
4) Unplugged everythng except headphones and power and turned the volume right up. It's Silent other than some very temporary noise in some parts of the turn, until I am 80% round where I then hear a faint hum
I can't run a powered USB as I don't have one, but given the bifrost is AC powered, and the same thing happens with it, I am inclined to think it wouldn't help.
Is there something I can do with a multimeter to test the crack for a ground loop?
1) Put the Crack Amp, PC and Dac into the same powerboard. - Noisy
2) Unplugged al PC peripherals, Keyboards, mice, other USB devices (basically nothing except power and Coax SPDIF) - Noisy
3) Switched from SPDIF to Coax Spdif - Noisy
4) Unplugged everythng except headphones and power and turned the volume right up. It's Silent other than some very temporary noise in some parts of the turn, until I am 80% round where I then hear a faint hum
I can't run a powered USB as I don't have one, but given the bifrost is AC powered, and the same thing happens with it, I am inclined to think it wouldn't help.
Is there something I can do with a multimeter to test the crack for a ground loop?
PassionForSound
New member
networkn said:
No (to ground loop testing), because there isn't one in the Crack or you would hear noise even with nothing plugged in. The issue you have is occurring outside of your Crack and being transmitted into the Crack via the source devices you're using (i.e. PC to DAC is where the noise is generated).
Can you use optical or is that noisy too (or not available)?
I know some people have tried removing certain power-related pins from USB cables with some success on this type of issue, but I don't know which ones or if it would work for you here. Perhaps someone can elaborate.
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