EggXpert

I did a basic google search of Antec Nine Hundred front panel audio static and I found that a lot of people have the same problem.  I figured out what is causing it so I thought I'd share.

 

More importantly I figured out how to fix it.  :)  The fix is to disconnect the grounding wire from the front panel and disconnect the firewire and USB cables.  :)  That's right.  If you want to use the front audio ports, you can only connect the front audio port to your audio card or motherboard onboard audio and nothing else.

 

The reason is that all the grounds for the front ports are connected.  The USB ground, the grounding wire and the firewire ground are all connected to the audio ground.  Some subcontractor probably got a little over-zealous with grounding things and decided that it was a good idea to connect all the grounds together....  Yeah...

 

Anyways, do a search for "audio ground loop" and you'll know why it's a bad idea to have more than one path to ground.  The audio port is supposed to be grounded through the grounding wire on the audio port.  It has its own grounding wire.  So do the firewire and the USB.  The reason they have their own grounding wire is to let the motherboard be the only path to ground so you don't run into these sorts of problems with ground loops.

 

I can go into explaining all this, but it's just a hassle.  The short story is that you should only have one and only path to ground at all times.  In audio, it's particularly noticeable because the ground noise becomes audible.  It's just as bad in USB and firewire because it means data loss and probably a much slower transfer rate because you'll have to do a bunch of error correction on the data transmission, which means frequent retransmission of the data.  But I'm just guessing on that part though.

 

Anyways, I hope this helps. 

So aside from disconnecting the USB and FireWire inputs, there is no other way to eliminate the hum? Would it be possible to run additional ground wires myself?

Actually there is something I didn't think of before.  You can probably CUT the grounding wire of the AUDIO CABLE to the motherboard.  I don't why I didn't think of that before.  But it's irreparable and if it doesn't work, you're stuck with a cut wire.  :)  And you'd have to cut them all I think.  The ground wire on the firewire and the USB too.  And then connect the grounding wire to the chassis.  That way, the path to ground for all three is through the chassis.

 

The only way to stop it is to have only ONE PATH to ground.

 

There is another solution that doesn't involve cutting.  You can spend like a bunch of money on something that cleans up power.  You just need clean power without any noise.  There are a bunch of products that does that.  Having clean power will making overclocking easier too.

removing 1394 and usb does not work. removing those and removing the ground does not work. it makes it much quieter, but discerning ears will still hear it. (alternativley if you DONT have a powerful graphics card it may be good enough)

 i cut the ground line on the audio. didnt work. i cut the ground line to the chassis. works. you need to remove both the ground on the audio cable AND the ground on the chassis and it works perfectly. zero noise whatsoever. so far  i have the USB and 1394 grounds still on and no issues. if issues arise with usb devices i will probably cut the ground on that also.

thanks for the solution.

err i just realized that when there is no ground, the sound card doesnt know that it needs to mute the external speakers. maybe i can find a way to ground it outside the case,

e60deluxe's solution of removing the ground from the cassis as well as the audio connector works...but it also makes my front headphone jack mono. I can tap the chassis ground on the chassis for a moment, and sure enough, I hear in stereo again, but the static comes back. This wont due. I still need a solution here. The OP's solutions didn't help at all.

Huh, I can't really hear the problem anymore.  If it's still there, that means that those cables are shielded at all.  I guess the real solution is to just to not buy the case in the first place?  :)  Or get a really expensive audio card with one of those front panel things of its own.

I just turned up the sound really loud, and you're right.  The noise is still there.  :)  It's really quiet, but it's still there.  That kind of sucks.  Oh well.  :)

I found a safer and easier way to eliminate the problem.

I have Antec 300, and i had exactly the same problem, I could hear static through front panel audio(HDA) when i moved mouse cursor, or hovered over the links in browser, and it was a DISASTER when i was listening through the music.

This was the first computer i made, so i was really impatient to try out my new config so i slapped everything together without paying attention to the cable management, and since audio connector is positioned all the way across the motherboard - Front panel Audio cable was hanging between CPU and videocard, and as I said - static was terrible.

Yesterday I disassembled my whole rig and decided to redo cables, and i put the audio cable around the motherboard and tucked it in there so that it wouldn't fall out. When i plugged in my headphones i couldn't hear any static at all -- even with my headphones and system volume turned to max.

 So.. no need to cut any wires and void your warranty, or buy expensive sound cards to get rid of the static, simply put the cable away from from all "calcuating" hardware, or if you have space - tuck it behind the motherboard.