Help with Interference issue [resolved]

[NightFlight]

Just my 2 cents here...

Don't defeat the safety ground on the crack. Even if it were to fix the issue. Crack -> You -> Ground  = bad place to be.  Better to fix the ground issues elsewhere.

 

[networkn]

You could try a cheater plug on the PC. A person might be inclined to try a cheater plug on the Crack, but of course as the manufacturer I have to discourage that as it defeats the safety ground in our product.

When someone said that ground loop occurs between components, did they mean between two electronic components such as resistors and diodes, or between components being DAC and AMP or PC and DAC?

Given I have tried SPDIF and SPDIF Coax and the problem still exists, I am pulling my hair out.

If I use the headphone jack (6.25) on my Soundcard I can't hear anything and if I use my USB Headset into the PC, I can't hear anything. Unsure if this is useful information.

Is it possible the house itself isn't grounded and is it worth at this stage considering a electrician come to the house?

Any other troubleshooting steps? The PC is pretty huge so moving it isn't really that practical, and the only other PC's are laptops. I could take my Crack and Dac to work and see if it's still a problem, but I imagine it's within my house.

 

[networkn]

One thing I wanted to note though I warn up front it COULD be a Red Herring..

I have a pair of RS170 Headphones, Wireless, made by sennhiesser and I have long had an issue with a hum in those, whenever sound wasn't playing. So when I watch TV, plugged into the Headphone Jack of the TV, whenever speech or music isn't play, say between scenes or if there is a long pause in conversation the hum/buzz appears, but goes away when speech/music resumes.

 

[Paul Joppa]

When someone said that ground loop occurs between components, did they mean between two electronic components such as resistors and diodes, or between components being DAC and AMP or PC and DAC?...

I said that, and I meant there was a noise current in the ground wire of the interconnect between two devices - specifically, with all the great information you have obtained, everything points to a current in the ground ware of anything that connects between the computer and anything else that is safety grounded.

When I say "safety grounded" I mean that the chassis and the signal ground are connected to the third pin of the power socket.

It's sooo hard to be clear with just words! Sorry for the lack of clarity. Computer power supplies are notorious for being noisy in several ways, this is just one of them. I think the computer power supply produces an output whose ground side is not bonded tightly (i.e. with low resistance) to the signal reference ground used for SPDIF, headphones, USB, or other outputs.

When you connect something that is not itself grounded to safety ground, that "something" has a ground which fluctuates with the computer ground. You listen to the difference between the "ground" and the "signal" which both fluctuate the same way and there is no apparent hum. It's only when the Crack or another safety-grounded device provide a path for that fluctuating voltage to generate a current (into the safety ground) whic causes the non-zero resistance of the interconnect to acquire some noise.

If you can get the digits to the DAC without a ground wire, there will be no current and no noise. That's why I suggested an optical link, but wifi or bluetooth would do the same. Failing that, a transformer between the DAC and the Crack is a traditional solution; the two windings are connected magnetically but not electrically. Unfortunately it can be expensive to get good transformers. At one time Radio Shack sold some inexpensive audio transformers to solve the same kind of problem in car audio installations, they were cheap but they were cheap if you get my drift.

 

[PassionForSound]

If you can get the digits to the DAC without a ground wire, there will be no current and no noise.

Paul, is this why some people suggest removing the power-related pins from the USB cable if the DAC is self-powered or is the noise carried in the digital audio signal itself?

 

[Paul Joppa]

Could be - I'm not knowledgeable on that hack!

 

[networkn]

Hi,

People have referred to the problem being eliminated by an optical cable, but as I understand it, that has already been tried by trying both SpDIF and SpDIF Coaxial, correct?

If the problem has persisted beyond this, then does this lead us to different steps in troubleshooting, or a more clear picture as to where the problem lies? The BiFrost has a 3 Pin power, the PC does and the Crack Amp. This means they are all grounded as I understand it.

Sorry if I still don't get it, it doesn't really make sense to me.
If Current is getting into the ground wire for one of these devices, wouldn't a current check or something allow us to determine if that is coming from the Crack?

The ODAC is USB powered, but the BiFrost is independently mains powered.

Given the O2 amp is 2 pin powered via mains and I can't hear any noise via that, then would it not indicate, the only conclusion is my PC has the issue?

If Categorically, I could hear if there was a problem with the crack amp, then it really only leaves the PC as the common denominator ? Do I need to pull my PC apart to see if I have a short or something?

Houses in NZ are supposed to be grounded too, wondering if that perhaps isn't the case with our place for some reason. Perhaps the grounding bar isn't connected properly? If that was the case I presume then that all my audio equipment in the lounge would be humming?

 

[mcandmar]

SPDIF Coax still creates an electrical connection, optical does not.

It sounds like a USB isolator might solve your problem as they remove any direct electrical connection between the PC and USB device.  They also have their own 5v power supply which is a lot cleaner than the 5v supply coming out of a PC. For a USB powered DAC this can make all the difference in terms of noise floor.

Up to now USB isolators were a DIY thing in that you had to cobble it together yourself, i built one of the Ciruits@home kits and put together a linear power supply for it. The guys at Beezar are just about to release a complete kit, i have built and tested one of their pre-production prototypes and can confirm it performs perfectly.  Keep an eye on the thread as it should be available to order very soon.

Main thread here https://www.head-fi.org/t/703334/doodlebug-usb-isolator
Pics of my unit here https://www.head-fi.org/g/i/1091976/beezar/sort/display_order/

 

[networkn]

SPDIF Coax still creates an electrical connection, optical does not.

It sounds like a USB isolator might solve your problem as they remove any direct electrical connection between the PC and USB device.  They also have their own 5v power supply which is a lot cleaner than the 5v supply coming out of a PC. For a USB powered DAC this can make all the difference in terms of noise floor.

Up to now USB isolators were a DIY thing in that you had to cobble it together yourself, i built one of the Ciruits@home kits and put together a linear power supply for it. The guys at Beezar are just about to release a complete kit, i have built and tested one of their pre-production prototypes and can confirm it performs perfectly.  Keep an eye on the thread as it should be available to order very soon.

Main thread here https://www.head-fi.org/t/703334/doodlebug-usb-isolator
Pics of my unit here https://www.head-fi.org/g/i/1091976/beezar/sort/display_order/

Hi There!

If Optical is also know as Toslink, then I have tried this and I still have the buzzing. so I have the problem via Toslink, Spdif over Coax, and USB.  How much do you think that Isolater will cost roughly?

A lot of these type of suggestions, seem to be a workaround, I would be interested in solving the problem itself, as usually these things can affect more than one thing.

I bought this today, it gets to me tomorrow. I am hoping it's going to work!

http://www.trademe.co.nz/Browse/Listing.aspx?id=740393126

 

[murray]

Houses in NZ are supposed to be grounded too, wondering if that perhaps isn't the case with our place for some reason. Perhaps the grounding bar isn't connected properly? If that was the case I presume then that all my audio equipment in the lounge would be humming?

Hi, I live in NZ too.  The electrical grounding system here is required for the safety of human life. If your house wiring is no longer correctly grounded then it will be in a dangerous state.  If you suspect that is the case then you should get an electrician to check it out.  For this reason never let anyone convince you to "lift the ground" or use a 2-pin AC plug in place of a 3-pin plug to disconnect the safety ground.  The suggested signal-level ground isolators are the safe way to proceed.

 

[networkn]

Hi, I live in NZ too.  The electrical grounding system here is required for the safety of human life. If your house wiring is no longer correctly grounded then it will be in a dangerous state.  If you suspect that is the case then you should get an electrician to check it out.  For this reason never let anyone convince you to "lift the ground" or use a 2-pin AC plug in place of a 3-pin plug to disconnect the safety ground.  The suggested signal-level ground isolators are the safe way to proceed.

I don't really think that is the case, it was just a theory from the guy at work.

I am puzzled by the comment the problem shouldn't occur over optical but it does. Perhaps we are all barking up the wrong tree.

Below is a picture of the PSU section of my AMP. Perhaps you would be prepared to post yours for comparison:

https://www.dropbox.com/s/xeehllzo0j18x0w/20140615_202252.jpg

 

[networkn]

I just got a lucky break. Not sure how I did it, but I was taking a photo of the Amp up closer and just got 240v right through the chest. (well that's where I felt it). Somehow I completed a circuit but I don't recall doing it. Crack was off, but power cable was in (was just a quick peek, but I learned my lesson but good).

So stupid, but luckily, still alive. Thankfully alive to learn that lesson.

Unfortunately I jumped back and let go of the crack so some stuff got a little bent, so I guess tomorrow, I'll need to redo all the resistance and voltage checks again, how annoying.

 

[Paul Birkeland]

If Optical is also know as Toslink, then I have tried this and I still have the buzzing. so I have the problem via Toslink, Spdif over Coax, and USB.  How much do you think that Isolater will cost roughly?

So with the Toslink connection, you have hum with the laptop plugged in and no hum with the laptop on batteries? 

I would triple check this situation, the Toslink cable should work. 

 

[NightFlight]

I just got a lucky break. Not sure how I did it, but I was taking a photo of the Amp up closer and just got 240v right through the chest. (well that's where I felt it).

I picked up the crack about a couple months ago while I was upside down while testing. My thumb apparently got to close to the AC socket. I felt that climb right up into my shoulder. NA is only 110-120VAC, but it will still get you if you dead short.

Unfortunately I jumped back and let go of the crack so some stuff got a little bent, so I guess tomorrow, I'll need to redo all the resistance and voltage checks again, how annoying.

My use the supplied 6080 and 9 pin when testing, as they are both 'cheap' compared to some of the other tubes I have. Just the some of the 12AU7 pins bent for me, which is trivial.  More upsetting was my own stupidity - evidenced by a long stream of curses I didn't think even I still knew.

 

[NightFlight]

So with the Toslink connection, you have hum with the laptop plugged in and no hum with the laptop on batteries? 

I would triple check this situation, the Toslink cable should work.

In my case my toslink (cheap five dollar job) seems to work as good as or better than the USB option on my DAC. I've tried expensive glass toslink, only to see it not be able to sync up at 192K, where as the plastic seem to couple better with the diodes on my motherboard. *shrug*

But Paul is correct, a toslink cable should provide electrical isolation from the computer in the chain.

 

[networkn]

So with the Toslink connection, you have hum with the laptop plugged in and no hum with the laptop on batteries? 

I would triple check this situation, the Toslink cable should work.

I don't have any noise from the laptop to anything. The issue is from my Desktop PC via any DAC to the Crack. I have tried Toslink, Spdif over coax and USB and all of them present with noise.

 

[networkn]

I picked up the crack about a couple months ago while I was upside down while testing. My thumb apparently got to close to the AC socket. I felt that climb right up into my shoulder. NA is only 110-120VAC, but it will still get you if you dead short.

My use the supplied 6080 and 9 pin when testing, as they are both 'cheap' compared to some of the other tubes I have. Just the some of the 12AU7 pins bent for me, which is trivial.  More upsetting was my own stupidity - evidenced by a long stream of curses I didn't think even I still knew.

Hi There!

I think everything is still intact thankfully. I will do the testing tonight. I don't recall touching anything in a way to make a circuit and I am wondering if I have something incorrectly wired around the ground, though voltages and resistance checks were bang on the three times I checked it so perhaps I just don't recall the reality.

My wife is a little concerned that the bottom of this crack isn't sealed and we have little kids one of whom is particularly inquisitive, so I need to be quite careful where I leave it etc.

 

[PassionForSound]

Hi There!

I think everything is still intact thankfully. I will do the testing tonight. I don't recall touching anything in a way to make a circuit and I am wondering if I have something incorrectly wired around the ground, though voltages and resistance checks were bang on the three times I checked it so perhaps I just don't recall the reality.

My wife is a little concerned that the bottom of this crack isn't sealed and we have little kids one of whom is particularly inquisitive, so I need to be quite careful where I leave it etc.

After checking your wiring, you might want to attach some sort of open grille / mesh to the bottom of your Crack to prevent little fingers (and big ones) going where they shouldn't.

 

[murray]

A suggestion: When you re-try the Toslink optical interconnect to isolate the DAC from the PC, make sure that no other wired interconnects are plugged in at all between them, e.g. unused coax, analogue, USB.  If they are, they will still probably couple the noisy ground of the PC to the DAC.  The ground shields will still electrically connect, even if they aren't selected by the DAC input.

 

[networkn]

A suggestion: When you re-try the Toslink optical interconnect to isolate the DAC from the PC, make sure that no other wired interconnects are plugged in at all between them, e.g. unused coax, analogue, USB.  If they are, they will still probably couple the noisy ground of the PC to the DAC.  The ground shields will still electrically connect, even if they aren't selected by the DAC input.

Hi There!

I never have more than one connected at a time.