[doctorcilantro]

EDIT to organize thoughts & workflow:


Hey all,

Well in the almost 10 years since I have doing PC audio, I'm stumped. Well, at the very least, highly frustrated, and I really need some assistance.

I built a small PC around a PicoPsu and mini-ITX board to replace my larger HTPC. This PC still does duty for family thus ethernet (direct to router via onboard) and HDMI are connected for 1080P to TV (and aux "crap" speaker use). That said, I have some kind of EMI/RFI issue.

It's a long tale so I'll try to keep it concise, which will be hard.
The Lynx card is not the source of contamination as I had this problem with an external/PCI based EMU1616M.

Summary of Prior Experience w/ Nasty Noise:

When I had my Nova, I noticed this noise when I hooked up my Oppo's analog output to the Nova for use with a Blu-Ray disc. The end result was EVERYTHING off with just Nova (Pre) & Minimax (power) amp connected with RCA interconnects. PC was NOT connected to the Nova, and when powered on certain cables would allow the EMI/RFI into the signal chain. When I swapped on some Cardas Golden Cross, the noise went away. Same thing on my modern Pro-ject mini tuner. The GC would solve the problem. So I was sure it was EMI from the PC, and that I needed well shielded cables. Now that I have direct tethered the PC to the DACs (before with 1616M, the PCI card connectes to a breakout box via Cat5), I'm not sure if it is riding the AES or maybe still just being picked up by my analog cables from pre>power amp.

Noise signature:

Pulsing static and mouse movements heard as extra fuzz; can be easily heard from listening position on 94db/w speakers @ 8feet.

Points of interest:

1. AES output 1 goes to DAC w/ headphone out: I do not hear this noise on the headphones (AKG601).

2. Same noise was heard with old sound card.

3. Noise crept into system last time just by connecting certain cables from pre (Peachtree Nova) to power amp (EE Minimax).

4. Same noise is also riding on USB cable to EE DAC.

5. Ran PC to separate circuit via ext. cord; no joy.

6. Get THIS, small pulse/whine upon PC startup (quiet, not a thump) but the whining and electronic wheezing doesn't start until AFTER Windows loads from the welcome screen (Windows 7 x64) when I enter my password.

7. I have one DAC connected to a Channel Islands passive, this is the DAC which has no noise on it's headphone output, but is noticeably than the EE DAC when connected to the power amp. POINT - I am using new cables, not the Golden Cross.

8. Disconnect all AES from DACs = no noise.

9. Connect Oppo to Channel Islands passive = noise (NO PC CONNECTED TO SIGNAL CHAIN!)

Possible future tests:

1. Alternate PSU - I have this PicoPSU which I am now wanting to replace with a standard ATX for testing purposes. The Pico has a laptop style AC adapter the molex type 24pin adapter that sits on the motherboard has caps on it...so that's where it's converting to DC? How does the board Chris noted work with power? Looks like at has a molex on the motherboard?

2. BIOS adjustments - It's definitely originating at the PC, and maybe I need to disable some stuff in the BIOS. I use the HDMI audio (aux audio) and the RJ45 ports

Here is an old post when I solved the noise issue last time:

Just an update on my noise issue.
Last night I put on a Blu-Ray disc and forgot I had unhooked the coax digital cable which I use to play decoded PCM from Oppo to Nova. Well, I forgot that Blu-Ray must have encryption because it is all white noise.
So I connect up an analog cable to the Nova and that EMI from my PC gets picked up right away. I tested my Pro-ject tuner w/ Cardas Golden Cross cables and did not get the noise; I plan on trying the Oppo with the Golden Cross. If my theory is right, I should hear no EMI.
Thus, cables do matter (as generic a statement may be, it is true). I think the HOSA cable must be like my other 2 cables, in that they have the shield floated at one end which acts like an antenna in this case.

Why are analog, single-ended RCA, connections more prone to allowing EMI/RFI into a system.

I had a problem with a preamp which also appears with a small modern tuner, and a BDP83.

At one point I know for a fact that a cable solved the problem, Cardas Golden Cross, whereas I believe my others have floated shields.

The BDP83 is connected to my DAC for testing with Tos. Coax. and HDMI to the LCD TV. A low PC is on the same circuit.

This noise is PC noise, static which can be heard "fuzzing" when I move the mouse. Just curious why only the analog connection allow some connection to this noise. My final test was with NOTHING connected to the speakers except amp and preamp which were connected to one another. When I powered on the 120w PC (picopsu), the noise infiltrated to the speakers, thus my assumption it was EMI/RFI.

Maybe this is powerline based?????

Maybe I should move the PC onto another circuit tonight.

[ctviggen]

You ran the test with no inputs to the preamp and still got noise on the speakers when moving the mouse?  Definitely try running a long extension cord to the PC from another circuit.  What happens if you move the PC over, say two feet away?  Interference of this nature is affected by distance, so if you move the PC away from the system and your noise goes down, you know it is RFI/EMI and not garbage put on the circuit by the PC. 

[doctorcilantro]

Thanks! It isn't easy to move really, well I could, but if an alternate circuit works, that would be ideal. I'm planning on placing my new TT just above the PC and my tonearm uses about 3ft of litz wire direct to phono pre (won't see any loss due to voltage divider action).

[doctorcilantro]

3rd party heatsink meant I could not put on the plastic cover for the Nexus Psile which had its inside lined with foam. The chassis is solid metal though (aluminum?). Here, you can get a sense of the distance (when I had the Nova). Now, I have the EE DAC which picks up these nasties (or similar) if connected via USB (which I won't be using).

I tried the tuner last night with no problem, but I swear it did used to happen with it too. The EE 6BM8 Minimax amp on right, is now where the Nova is pictured on the left.

[doctorcilantro]

Oh man is this infuriating.

I just got my custom cables for my new Lynx AES16 card. Hook up one to my EE DAC and the same damn noise floods the system.

Moved PC onto separate circuit; no joy.

Get THIS, small pulse upon PC startup (quiet, not a thump) but the whining and electronic wheezing doesn't start until after Windows loads from the welcome screen (Windows 7 x64) when I enter my password.

I have this PicoPSU which I am now wanting to replace with a standard ATX for testing purposes. The Pico has a laptop style AC adapter the molex type 24pin adapter that sits on the motherboard has caps on it...so that's where it's converting to DC?

I've never had this problem in all these years of doing this until I built this small PC. Hell I had 102db/w horns on my last setup.

It's definitely orginating at the PC, and maybe I need to disable some stuff in the BIOS. I use the HDMI audio (aux audio) and the RJ45 ports

My original post was describing this same noise but I did not have the PC connected to the system as the cables just came today. These are supposedly well shield Gotham Audio AES/EBU cables so it would seem that besides EMI/RFI, it's riding on the cables from the PC (same noise with USB connected to DAC).

crap.........what the heck is my next step? Alternate PSU? New motherboard...! Argh.

[wilsynet]

So is the PC not connected to the audio system at all and you still get the noise?  In other words, no HDMI, no USB, no AES.

[doctorcilantro]

This has gotten worse.

Last night I received my Lynx AES16 output cable which has (2) XLR outputs so I can run one to each DAC (one for seperate headphone use).

So, as soon as I connect the AES cables to either DAC, this noise comes on, strong. Probably 5-10db? Constant of weird psu static/pulsing, which can be heard from the couch.

Unplugged everything on the circuit except amp & DACs (and a passive pre from Channel Islands - only powered for remote control).

PC  is off; all is quiet (turned off the Addonics hard drive enclosure too).

Turn on PC, noise sorts of starts then stops at Windows 7 logon screen. Upon login, it goes crazy. Onboard ethernet? WTF?

Points of interest:

1. AES output 1 goes to DAC w/ headphone out: I do not hear this noise on the headphones.

2. Same noise was heard with old sound card.

3. Noise crept into system last time just by connecting certain cables from pre (Peachtree Nova) to power amp (EE Minimax).

4. Same noise is riding on USB cable to EE DAC.

5. Ran PC to separate circuit via ext. cord; no joy.

I wonder if the EMI/RFI was previously picked up by certain cables, and possibly still is. However, now that I have directly tethered the PC to the DACs via AES, is it riding that now?

Archived post of my issue when I had the Nova:

Originally Posted by doctorcilantro  View Post
Just an update on my noise issue.

Last night I put on a Blu-Ray disc and forgot I had unhooked the coax digital cable which I use to play decoded PCM from Oppo to Nova. Well, I forgot that Blu-Ray must have encryption because it is all white noise.

So I connect up an analog cable to the Nova and that EMI from my PC gets picked up right away. I tested my Pro-ject tuner w/ Cardas Golden Cross cables and did not get the noise; I plan on trying the Oppo with the Golden Cross. If my theory is right, I should hear no EMI.

Thus, cables do matter (as generic a statement may be, it is true). I think the HOSA cable must be like my other 2 cables, in that they have the shield floated at one end which acts like an antenna in this case.

DC

[doctorcilantro]

I am planning on trying tonight:

1. Checking continuity between the computer chassis and earth ground.

2. Using my neighbor's 24pin ATX power supply.

3. Trying to ground my PSU and PCI to chassis (long story).

See below - I had forgotten about these lapses in integreity on my system:

My stupid mini-ITX case (NEXUS PSILE), although it has a PCI slot, won't allow a PCI card to be installed unless I take off the mounting bracket on the PCI card. Often, it seems the traces on the board are grounded to this bracket which couples the card to the chassis. What a piece of crap this box is.

Secondly, my stupid ITX case doesn't allow for my PSU connector to stick through; it is like a laptop AC adapter, the PicoPSU.

So this is well, the small ring where the AC adapter connects, is not coupled to the chassis.

My last card an EMU used a breakout box but was still PCI based; I ad to take off the mounting bracket on that PCI card as well.

[Tyson]

Try a different PC in your system.

[doctorcilantro]

I think it's more telling to put a new PSU in my existing system rather then spend time dragging my neighbor's PC over and installing the Lynx hardware and software, but yes, maybe eventually.

If I change PSU, that will tell a great deal.

Is this "coil whine" coming from my PSU, or from my onboard graphics/mb?

Interesting links/points:

http://forums.overclockers.co.nz/showthread.php?t=18972

http://hardforum.com/showthread.php?t=1393005

I'm sure I read somewhere that ATi was using Digital PWM now (which should theoretically prevent the issue... They were supposed to have started using it in the 2900 series, reverted to analogue in the 3xxx series, and now be using Digital PWM again in the 4xxx series, but I've heard people complaining about coil whine in 4xxx series cards...

My onboard video happens to be ATI 3200 series.....

[jrebman]

Jon,

It could well be a combination of these things -- poor computer case grounding, fast graphics card, ICs picking RF, etc.

I was sort of expecting problems today when I moved my Asus EEE box and Iomega usb drive over to  the audio rack, but things were actually better -- probably because of the shorter, much better usb cables both to the drive and the dac.

The noise you describe sounds very much like the noises I was getting through my Proton before I bypassed kmixer and went with ASIO4all.

Will be interesting to see what difference the PSU makes, but I'm with Tyson -- if you can try another computer, that would be helpful.

-- Jim

[doctorcilantro]

Thanks Jim. P picked a Harmon Kardon tuner for 75 shipped on audiogon and it sounds incrdible, WHEN I turn off my PC.....

That's why my Pro-ject tuner never sounded so good, I mistook my current EMI for FM interference.

I brought 3 psu's from work and will try them tonight. My neighbor's PC may be making a foray into my living room soon....

J

[davidR]

These problems can be so frustrating and pesky even for power & grounding experts who are paid good money to address those issues in studios etc. Could you pick up a cheap EMF meter from Radio Shack and do some experimenting to narrow down the source of your noise? This is a solid way to find the problem. It seems like the PC to me from what you have said. Moving it a good bit away from your rack would probably be good because your gear is in very close proximity to a radiator of noise (PC).  Is your case aluminum? You might need to pick up a cheap aluminum case and ground it, as well as fine a good ATX supply with solid dc output quality. If you'd like I can give a list of options for tested, quality ATX supplies. I think that's one of the key elements with the Macbooks and Mac pro sound differences compared to the Mac Mini, their chassis' are aluminum and the mini plastic. I know you know these things, but just adding to the discussion. We'll get it worked out and get your tunes pure again. 

[gerald porzio]

Are you using shielded cables wherever possible?

[doctorcilantro]

Thanks David.

You can see in the pic that while the case is aluminum? and also has a huge chunk of aluminum inside as the base for a heatsink, the top was plastic and lined with foam on the inside, thus I just left it off.

I have not moved the PC, just switched circuits.

If I plug in the laptop style AC brick to my PC, I get a pop and whine through the speakers which continues until I power up the PC. The whine and noise can be changed my rotating the AC brick in my hand. It's a 110w from eDac which comes with PicoPSU's.

I fear it is riding that AES cable as well as being emitted as EMI. Is still EMI per se if riding the cable; I'm not sure if "EMI" is reserved for when it radiates through the ether ; ) Is it just electrical interference on the cable;  I was not a physics major.

I can only move my PC so much and maintain the AES connection, but it would be a good test to start with the PC in the kitchen or something and turn it on, and have it load to the OS automatically. Then I could try the max length of my AES cable which is 8 feet IIRC.

I could order a new PicoPSU and try the new power brick, then try the new PicoPSU. They are two separate pieces of the puzzle.

[doctorcilantro]

Thanks for reminding me as I did get rid of this problem before simply by swapping in that Cardas GC (thanks Randy!).

AES/ EBU cable - The cable is Swiss made Gotham GAC-2 AES, with its unique
double Reussen shielding. The Vampire Wire XLR connector has solid copper pins that are direct gold plated, no nickel. The D-Sub connector has gold plated pins to match the Lynx card.

Other interconnects currently uses: unshielded Yacco Lucky 7, MAC Reference (dampened heavily but possible unshielded?), and I have some Tom Tutay Blue Velvets that did not fix the problem.

The GC cables is on loan to a buddy. Seems like I need to step back and simply try some solid cables first.

[gerald porzio]

There's no reason in this day & age not to use shielded cables, particularly when you have RFI issues. Why not stop the RFI @ it's point of origin?

[doctorcilantro]

There's no reason in this day & age not to use shielded cables, particularly when you have RFI issues. Why not stop the RFI @ it's point of origin?

I want to reduce the EMI/RFI as much as possible at the source, but I know there will still be some with a PC in the mix. I'm ordering a new power supply now, and I'll evaluate my cable stock tonight. Might have to get rid of some of these. Blue Jeans cable probably makes cheap yet well-shielded cables???

thanks
J

[doctorcilantro]

Did a little reading on Jetway, make of my mini-ITX board. Sounds like they use 4-layer boards and good caps.

# AMD 780G Chipset + SB700 Chipset
# Support Socket AM2+ Quad core Opteron & Phenom
# Integrated ATI HD 3200 Chipset
# Advanced 3+1 PWM Design
# Solid Polymer, long life capacitors

I may try to flash the BIOS but I have a new PSU on the way.

[jrebman]

Jon,

Sometimes that foam in the plastic top is actually an RF shielding foam -- what happens when you put that plastic top piece back on?

-- Jim