Crazy EMI/RFI with low power PC

doctorcilantro · « **Reply #20 on:** 16 Mar 2010, 08:13 pm »

I'll try, thanks Jim!

wilsynet · « **Reply #21 on:** 16 Mar 2010, 08:15 pm »

Rather than something exotic, how about something cheap. Low capacitance, well shielded, and very well tested: the Blue Jeans LC-1.

http://bluejeanscable.com/store/audio/index.htm

doctorcilantro · « **Reply #22 on:** 16 Mar 2010, 08:16 pm »

That's what I'm after. I used to have one of those for a headamp.

thanks!

gerald porzio · « **Reply #23 on:** 16 Mar 2010, 09:14 pm »

I'll 2nd the Blue Jeans LC-1.

davidR · « **Reply #24 on:** 16 Mar 2010, 10:26 pm »

Can you return the PicoPSU? Have you tried your neighbors power supply yet?

doctorcilantro · « **Reply #25 on:** 17 Mar 2010, 08:06 pm »

Quote from: davidR on 16 Mar 2010, 10:26 pm

Can you return the PicoPSU? Have you tried your neighbors power supply yet?

Hi Dave - Pico is out of warranty. I have in hand a cheap component cable from work (hard for me to get out to a store w/ new baby), and I have a Shuttle-compatibility mini-itx PSU on order which houses everything in one chassis, unlike the Pico. That should be here soon.

I will also try to borrow my neighbor's PC tonight, but again, I'm on daddy-duty most of the time so I have to be careful how I spend my free time....

http://www.newegg.com/Product/Product.aspx?Item=N82E16817338045

doctorcilantro · « **Reply #26 on:** 17 Mar 2010, 11:01 pm »

Designer of picopsu:

Quote

All DC electronic devices with removable power cord are not grounded to true Earth, like an AC/DC adapter would be.... As fas as I understand both GND and V+ are floating. And this can create unbalances, especially of you connect to the PC a devices that is directly grounded (such as a monitor) or peripheral that has own AC/DC adapter

Delta Wave · « **Reply #27 on:** 17 Mar 2010, 11:27 pm »

Is there anyway to move your sound card further away from your video card? I was having the same problem. But I have a full size tower so I was able to move my sound card all the way to the bottom of my case to the very last PCI slot. If you can't you may want to try a little DIY shielding to separate the two sound/vid processors. It drove me batty but now my PC is a most excellent music server.

doctorcilantro · « **Reply #28 on:** 18 Mar 2010, 12:07 am »

What pci audio card are you using? I have onboard video so.....

Delta Wave · « **Reply #29 on:** 18 Mar 2010, 01:45 am »

I'm using a HT Omega Claro Plus+. It's not shielded very well, which I obviously learned the hard way. You may even try re-seating your sound card. PC's can give you a bit o' drama at times... I've built a few.

doctorcilantro · « **Reply #30 on:** 18 Mar 2010, 03:23 am »

I now agree that the logical first step of trying another PC would control more variables; just hard to make that happen right now.

1. The noise was in the system with my last PCI card (EMU1616M), but was being filtered as it is by the Matrix Mini-i DAC headphone output.

2. Putting the PC in the kitchen results in no noise, but it is disconnected from the DAC.

3. Getting it connected to the DAC instantly brings about the noise.

4. I grounded the motherboard and Lynx to earth ground - with no positive results.

5. I tried 2 different fully shielded RCA cables between DAC and preeamp - with no positive results.

6. I tried 2 differest AES cables as Wayne just sent some demo cables - with no positive results.

It's either bad caps on the motherboard or a failing PSU; I'm leaning towards the PSU.

Delta Wave · « **Reply #31 on:** 18 Mar 2010, 03:38 am »

Do you have ALL of the ancillary features of the sound card turned off? (IE; no bass management, EAX...etc.) Is the digital output of the card matched to what the DAC can handle as an input?

doctorcilantro · « **Reply #32 on:** 18 Mar 2010, 03:42 am »

Well, yes, it is a Lynx AES16 with few if any ancillary features, and I don't use multi-cable snakes just dedicated playback and record cables with BNC word clock input.

The fact that this exact same noise was here last month with a different sound card speaks volumes ....

thanks
J

wushuliu · « **Reply #33 on:** 18 Mar 2010, 07:44 pm »

Just to clarify. So when you had it in the kitchen, when you added the dac you heard noise? or were you not able to attach the dac at all in the kitchen.

PSU, then graphics card does sound like a good place to start absolutely. I remember having sound card/graphics card issues somewhat similar back in the day. Some just don't play well with others and noise creeps over. Dunno what your specific setup is but swapping PCI slots for the sound card is another quick option (dunno if that dates me, it has been a few years since I messed around w/ PCs).

edit: i see someone mentioned something similar above.

doctorcilantro · « **Reply #34 on:** 18 Mar 2010, 07:57 pm »

Right, too far for hookup in the kitchen. I got distracted too, and started snacking on leftovers at 2am.

I too remember back in the day when we had to jump PCI slots; this mini-ITX board only has one though.

I should try the Cardas cable when it comes back. The two new ones were those faux high end Rat Shack RCA's and a component cable from work. However, this (the Cardas) was before the DAC was connected direct to PCI; the 1616M has the breakout box which acting as an intermediary, and then that connects to PCI via Cat5. As soon as I connect the DAC to Lynx I get the noise.

Hmmmm....I have an onboard sound card with 1/8" jack that I usually run as an aux zone to my outdoor speakers via Gainclone amp. I should try that into the signal chain tonight.

PSU will be here tomorrow and I commandeerthe neighbors PC tonight!

doctorcilantro · « **Reply #35 on:** 20 Mar 2010, 04:10 am »

I hooked up the 1/8" motherboard output to my power amp. The noise was worst of all other configurations; go figure. It was loud!

The small 200w psu arrived from Newegg today; still have the EMI on the system.

I'll try another PC and take a closer lokk at the caps on the motherboard on Sat.

DC

doctorcilantro · « **Reply #36 on:** 20 Mar 2010, 10:26 pm »

Hooked up my neighbor's pc and the noise signature was gone. Just a little rfi on the right speaker; could very faintly hear radio chatter which I had heard none of before. Seemes like a new motherboard is in order.

J

jrebman · « **Reply #37 on:** 20 Mar 2010, 11:05 pm »

By a different manufacturer? I'm guessing this is a design problem and not limited to that one particular board.

-- Jim

Telstar · « **Reply #38 on:** 23 Mar 2010, 09:01 pm »

It looks like psu or motherboard related.

I have a Winmate dc-dc psu which is similar to the pico but much better quality. Before i had a normal psu (with fan).
Replacing the psu with one proved to work is a good idea. The pico is not well filtered and may be the cause. Also it could be just the wall wart that you use with it.

If it doesn't work, go for the mainboard.

doctorcilantro · « **Reply #39 on:** 25 Mar 2010, 03:06 pm »

I'm going to cry foul on the onboard graphics.

Unplugged HDMI turned off TV (as in past) and everything points to the HD3200 integrated graphics.

1. Change resolutions: when TV is in between modes (no picture) the sound stops.

2. IRONICALLY, when I grab a scroll bar for Firefox, for example, and move it up/down very fast, sound stops. (the gpu is downclocking out of 3d mode most likely into 2d mode)

3. Underclocked gpu core in BIOS with no luck; 500mHz to 300mHz.

4. Noise gets really bad when loading into graphics heavy Windows desktop (32bit Aero etc.); disabling downgrading settings doesn't haelp.

5. Tweaking ATI Catalyst Control Panel settings does nothing.

It's a power issue with the board related directly to the graphics. Something has gone bad as I never had this problem at the start of the build.

Checked all grounding, still have noise.