Powerline noise

[BigPete]

Hello. I just recently built a Crack and im getting some background static noise. I have seem to isolate the noise to the powerline.

My current setup:
PC Foobar-> Essence One-> Crack-> HD800

My Crack is plugged into the same outlet as my PC and surge protector. When the PC is on i hear the noise. When running programs that use more power from the PC the noise gets louder. I plugged the Crack into another wall outlet farther away form the PC and there is a different noise. The background noise does seem to get less when i plug it to a far away outlet with an additional surge protector and no other components.

The noise from the PC and the noise from the far wall outlets seem to be 2 different sources. At times the noise at the distant outlets gets very loud when first turned on then goes away, other times it is constant. I tested these static noises with the Essence One amp/dac off and i still get the same noise so i doubt it is a ground loop or any interference from the Essence One.

The weird thing is the outlet at my PC seems to be the only constant quiet outlet, until i turn my PC on that is. Distant outlets have nothing plugged into them.

I bought a separate Tripp Lite ISOBAR4ULTRA surge protector tested in different configurations with my setup and still the same background noise interference. Any thoughts are appreciated.

Does the Crack have some sort of nonelectrical noise filter? This is what is seems to be. I do not get this noise when i have my HD800 connected to my Essence One DAC/Amp to my PC with the same outlet.

 

[Doc B]

I would not rule out the idea that the PC is radiating noise that is being picked up by the tubes rather than thru the powerline. You might try additional shielding of the PC or adapting a tube shield to the 12AU7.

 

[BigPete]

I would not rule out the idea that the PC is radiating noise that is being picked up by the tubes rather than thru the powerline. You might try additional shielding of the PC or adapting a tube shield to the 12AU7.

Thanks Doc, I will try a tube shield. Is there anything I can use from the local hardware store for a shield? Also there is zero difference in the background noise when the Crack is right next to the PC vs when I move the Crack away from the PC, which is about 8ft. It definitely feels like it is directly related to the PC power usage. When an application is open where the graphics card is stressed, the background noise gets much loud. Regular desktop use, the nose is much quieter.

 

[mcandmar]

I have exactly the same problem when i use a SPDIF connection from my PC to DAC, anytime there is movement on the screen i hear a bzzzzzz noise in the background.  Its fine using USB though.

I would suspect its noise coming from the PC over the ground line.  Try to isolate exactly where its coming from by disconnecting the DAC from the Crack and see if you can still hear it, i.e. is the noise coming through the interconnects or mains.  If it is from the DAC try disconnecting it from the PC and see if the noise is still there.

Also what connection are you using from the DAC to PC, SPDIF, Toslink, USB?

 

[BigPete]

I have exactly the same problem when i use a SPDIF connection from my PC to DAC, anytime there is movement on the screen i hear a bzzzzzz noise in the background.  Its fine using USB though.

I would suspect its noise coming from the PC over the ground line.  Try to isolate exactly where its coming from by disconnecting the DAC from the Crack and see if you can still hear it, i.e. is the noise coming through the interconnects or mains.  If it is from the DAC try disconnecting it from the PC and see if the noise is still there.

Also what connection are you using from the DAC to PC, SPDIF, Toslink, USB?

Hello Mcandmar.
Yes you are describing my noise perfectly with any movement on screen. I think you may be on to something. Here is what i tested and my results. Oh and my dac is connected to PC via USB.

I ran a benchmark "Unengine Heaven" to stress the graphic card as that is when the background noise is the loudest.

-everything connected regular pc-dac-crack-HD800 :      the buzz sound is the loudest 10/10
-everything connected but dac turned off :                    buzz sound slightly lower volume 9/10
-DAC usb disconnected from PC :                                    buzz almost gone, but still slightly audible 1/10
-RCA disconnected from Crack :                                      buzz completely gone 0/10


Ok here is whats weird. I disconnected the RCAs from the back of my external DAC and the noise was gone. BUT when my hand was resting on top of the E1 dac and my finger was touching one of the RCA connections, then the same noise came back. Even though the external dac was off, the PC noise seem to travel though the dac and though my hand to complete the noise circuit again. Just to clarify when my hand is not touching the dac and my finger touches the RCA connector i get that regular distortion buzz when touching a rca connector, it is a completely different sound than my PC buzz noise, which can be a rhythmic buzz depending on what i am doing on the PC. Am i just completely misunderstanding this?

 

[JamieMcC]

It could possibly be your RCA cables picking up the noise. I had a similar noise which disappeared when I found out by accident that a twisted pair of connecting RCA leads resulted in the noise disappearing. Thinking on how the internal rca cabling is braided to help cancel out interference I tried reconnecting without the twists = hum, then reconnecting with some twists put in with good results.

It might not work but its an easy thing to try and you never know it just might be that simple to fix.

 

 

[mcandmar]

As i suspected the PC is injecting the noise over the USB bus or ground.  As to how to best cure it i cant really say, but here are a few things to try.

-It could be poor filtering in the PC power supply, rather than replacing it try connecting it to a filtering multiblock or UPS, and connect the amp/dac to the mains the other side of it.  Idea being to create that barrier between them. For example in my setup i have a two way multiblock from the wall, one socket goes to a UPS that feeds the PC, Monitor, Cell phone chargers are other misc supplies.  The other socket goes through a mains filter box which feeds all the audio equipment, DAC's, Amps etc.

-Try different USB ports, some motherboard will have multiple ports, and sometimes from different controllers so you may find some are noisier than others. In my experience USB3 interface's are generally quieter and better quality.

-USB Isolators, these will break the connection between the PC's USB Power and chassis ground of the computer so when used with a dedicated power supply there is no path for the noisy PC power supply to reach the DAC.  I built an Isolator box with a Linear power supply to do exactly that.  No guarantees it will fix your problem, but i can say my Isolator made a huge difference for me.  In my case the DAC is USB powered so the cleaner USB supply was a benefit in itself.

Here is a nice little all in one kit currently being developed that should be available any day now https://www.head-fi.org/t/703334/doodlebug-usb-isolator , by chance i just built and tested a pre production prototype of that board last night and it performs just as good as the unit i built myself.  As far as i know he plans to sell them assembled in a box ready to go, all you need to do is connect a 9v DC power source to it and away you go.

@Jamie, buy yourself a length of Belden 19364 shielded cable and make a power cord.  It has a foil outer shield so almost completely kills EMI radiation.  I have an EMI detector which is great for finding power cables inside walls etc, i can touch it up against that cable and it still cant see it.

 

[JamieMcC]

Mark I have been pondering on this for a while now actually and wondering if its worth adding some sort of power line conditioner also. Funds are a little limited at the moment but it is defiantly on the cards for the future.

By the way I have just ordered some ring magnets and am going to have go at building a magnetic floating isolation platform to sit my Crack. I'm hoping to keep the costs under £20. My best sounding tubes are also the most sensitive to any vibration. While its not really a problem thought it would be a neat thing to have a go at cobbling together.

 

[Paul Birkeland]

Toslink will break the ground connection, give that shot!

 

[JamieMcC]

I'm also using toslink now by the way

 

[Deluk]

I suffered this buzz for over a year, audio from PC to HI-Fi, with the associated noise from things happening on screen. Worse with any flash stuff on ads but it would even keep time with any clock on screen that was ticking over the seconds. You could play tunes by whizzing the cursor about. The noise would hide under any loud music but there was always something wrong with the sound. Was feeding a Rotel pre into Quad II'a to Klipsch Quartets. On a whim I bought  Luxman L30 so that I could, maybe, get on and service the Quads. Noise was even worse through the Luxman. In a sort of eureka moment I lifted the ground on the power plug to the Luxman and  everything went totally silent, except for the music that is! Virtually no noise at full volume with my ear at the tweeters.  The cure/reason? The PC was powered from one socket and the Hi-Fi from another so the audio feed from the PC was causing a ground loop. If you don't find a similar loop I'll be very surprised.

 

[BigPete]

Thanks for everyone's input. I have been working like a dog 13 hr shifts back to back so i havent had a lot of trouble shooting time. I did try a all of you guys tips quickly before i went to work.

All of the mention trouble shooting methods had no effect, EXCEPT connecting the Toslink cable instead of the USB. Zero noise WOOT WOOT!!!!!! That celebration was short lived as i had driver issues with connecting my motherboards Toslink to my E1 dac. Looks like im going to do some driver tweaking to get it working properly.

But this was the first time i had all components connected to the same outlet, turned on, and a solid black quiet background. That felt nice!

Only drawback is i believe i will loose the "Bit perfect" option of my Essence One dac going toslink vs USB input.

The noise seems to be something to do with the usb grounding as some of you have stated.

I will reply back when i get the Toslink connection working properly.

 

[Grainger49]

    .  .  .    All of the mention trouble shooting methods had no effect, EXCEPT connecting the Toslink cable instead of the USB. Zero noise    .  .  .  . 

This nails down the source to your computer.  The problem, of course, is they are not intended to be a hi-fi source.  But they are very convenient as a source.

Knowing this you can get a lot of help from the compu-gurus on the forum.  Everything from improved power supplies to isolated outputs will help.

Try Grainger.com for the copper clad wrap (no relation).  You solder on a grounding wire, wrap the 12AU7 and ground the wire to the tube socket mounting screw.  This will effectively shield the tube.  But if all the noise comes through the connection to the computer this will have no effect.

Good luck!

 

[kgoss]

Try different USB ports on your computer. It might not help but it won't cost anything to try. The problem is USB provides (noisy) power to devices pugged in so your DAC is picking up the noise and passing it to the amp along with the music. If your DAC does not rely on the USB power you could build a USB cable that does not have the power pin connected. I never built a USB cable so I have no idea how hard they are to terminate.

 

[STURMJ]

Toslink may be the best solution here, pure digital signal, not affected by emi. A better usb cable might work, because it is probably interference caused by the powered lines in the cable ( a better usb cable should isolate these from the signal lines. However its hard to tell which cable is better since more $$ does not always mean it is better).

 

[mcandmar]

I needed to chop up a cable for my isolator build and picked up a couple of Belkin USB 2.0's.  Internally i found the +/- power were a larger gauge than the data lines, each set was twisted separately, wrapped in a foil shield, then the entire lot had a braided shield over it.  Seems pretty overkill to me, and that was just an off the shelf cable from a regular manufacturer.  From what i have found if its USB 2.0 compliant it will have all that which is more than enough basically.

Though apparently $200 solid silver cables sprinkled with fairy dust can give you a larger sound stage and more resolving micro dynamics

 

[feralcoder]

Sorry to revive very old post, but it's a timeless topic: "hearing PC power noise via DAC".  All solutions so far have presumed this noise is present and needs to be removed: at source (PC power conditioning, expensive PS, etc), in transmission (toslink works if DAC not powered by PC), or even from the post-DAC signal. 

These are all much more technically difficult and expensive than fixing the root of the problem: decouple the DAC entirely from the PC's power.  This can be done with a USB hub.  The PC's USB connection to hub may be noisy, but who cares, it's digital, then repeated - a USB hub is very similar to a network switch.  The hub is independently powered from a cleaner source, maybe 20 feet from PC, so the USB signal to DAC has a clean power baseline, no PC noise to remove.

I'll point out that the PC noise problem is many problems: PS noise, component noise, fans, wall line noise...  All irrelevant, just decouple all of that from the analog chain with a USB hub.

 

[Paul Birkeland]

A self powered USB hub could indeed work.