Antec Case Headphone Jack hack/mod

[Rake]

Hey ocau .. long time no see

Thought I'd share a quick hack I did. I found the Headphone jack on my Antec 300 case produced interference, this quick midnight-snack 10 minute jobbie fixed it up good and proper. A quick google suggests other cases may suffer this. Weather or not it does and if the same fix will work for other cases I can't say, thats for you to investigate on your own, but if you're aiming to fix a crackly headphone jack like I then this might be worth checking out.

Background if anyone cares

I have an Antec 300 case, and until this evening I had run a 3.5 lead to the rear of the computer for my headphones. All worked fine and sounded good. However I decided I'd like to use the front output on the case for my headphones, so I can venture a little further without having to take them off, and free up a 3.5mm lead I needed (i had 2 linked with a joiner for length to reach around desk).

I have an X58 board, i7, HD4870x2 and 4 hdd's so this case is crammed, so only now did I bother to pull the lead through and plug it in. Did that all good, plug in my headphones and oah! Interference city! Started up some music and it sounded fine, but quiet or no sound would have a moderate buzzing and popping clearly audible. Really annoying. It couldn't be a sound card issue because using the rear output worked perfectly.

This might be obvious to some people, but maybe not everyone so I'll say it anyway. The problem is additional earthing. Out of curiosity and knowing earthing issues can cause all sorts of headaches (cars heh) I connected a multimeter to the case and the outmost socket of the headphone jack, checking resistance. Clear connection. Same for the USB plugs.

To test further I unplugged the plug to the sound card. Same thing. Unplugged the USB header plug. Still earthing. There is a small wire that leads over to the case and screws in, obv a ground, removed, no more connection. Check continuity between the Headphone jack and the earths on the USB, clear path.

So it was obvious Antec, in addition to the standard earthing lead from the headphone jack to the sound card plug, ran a 2nd earth wire which essentially just grounded straight out to the case chassis.

Since I had nothing to lose, figuring I'd just abandon it and go back to the other cord, I cracked open the case with the audio jacks and usb ports, removed the earthing, plugged everything and voila! perfect sound with no interference at all.

Mmmm how?

Pretty easy. Turn off computer and unplug the USB and Audio headers. Take off the front of the case, and remove the plastic casing which houses all the front panel sockets.

The case is pretty well sealed, upon observation the top just seems to clip in somehow, and also holds the sockets in place. However there was nothing less than brute force that was able remove the top, I snapped mine a bit, but couldn't find a more graceful way of doing it.

I used a small jewelers flathead screwdriver for leverage, using the headphone jack as a pivot. Once lifted, stick another driver in to hold it and do the same using the Mic jack. From there it should be enough to pry with your fingers. Avoid levering against the USB sockets, the metal surround on these is very weak and bends easily. If you've a different case you're on your own

Excuse the poorish pics, bad lighting, was just quick and dirty.


Click to view full size!

See the orange wires that solders to the side of the left-most USB socket? One goes to the other USB socket,which then connects to a black wire that runs to the case chassis. The other runs under the cables exiting the casing to the right hand side where the headphone and microphone jacks are.


Click to view full size!

So again in essence the jacks have 2 earths - one wire that runs to the sound card, and antec's bright idea that runs to the chassis. The latter is causing our interference problems, so all we gotta do is cut this orange wire to isolate the jacks.


Click to view full size!

Snip!

Now the Mic and Headphone jacks will be forced to earth (as they're meant to) through the sound card and not directly to the case chassis. The USB ports will still earth as before, not that it's essential either.

Put the case back together best you can, mine still seemed to click closed OK even though I had to break it to open it. Put everything back together, plug in the USB and Audio plugs, and test it out!

[Sorak]

i have a coolermaster 1000 case, the front jack has the same problem, im no electrician so didnt know what to do, thanks for the information, ima go crack mine open to see if i can fix it. hopefully i dont completely damage it

upon inspection it looks like the plastic casing around the top and front overlap the front pannel. this might get messy.

[ECHO]

Wonder if this is the cause to my p180b problems? :|

Antec even sent me a brand new front panel audio connection which didn't solve it either. Looks like I'll have a closer look to see if this is applicable in my case.

[Quan-Time]

wow,, ive noticed that on my old PC.. always thought it was the header or some crazy issue.. never realised it could be this..

Great info.. and lucky you for realising this before it sent you nuts !

[Rake]

Whoa .. ocau front page, nice

Let us know how you go guys!


I first googled around a bit for a solution, didn't find any fixes but did discover I wasn't the first. Having fiddled with a lot of car electrics over the past few years, grounding is always something well worth checking. Everything above just sprung into my head straight away, pulled everything apart and whaddaya know .. suspicion confirmed.

Of course my post pertains only to my case, all of your cases could suffer the same identical design flaw, or not at all. I guess that's for you guys to figure out.

To elaborate: The simplest way to check I found (as mentioned in first post) is to:

1 - Unplug the audio header from the case sockets (for testing integrity)
2 - Put a multimeter on resistance mode
3 - Check for continuity between the socket and the case chassis. If putting the multimeter probe in is tricky for you, plug in a 3.5mm-3.5mm lead and put the multimeter on the other end of the lead. (The earth is the end opposite the tip).

If there is continuity, the multimeter will display a low/no resistance. This means the socket grounds to the chassis, likely as well as the soundcard header. This is what causes the issue, atleast it did for me, and therefore finding and severing the extra earth should in theory fix your problem. On the contrary, if there is no connection, your multimeter will usually show "1", or the same as not having the probes touching anything, whatever that may be depending on your multimeter, and thus your fault might lie elsewhere.

Another consideration could be that the Sound card itself is the culprit. It's always a possibility. But like in my scenario, since the jack on the card itself worked OK, I expected the card header to be just as reliable. I'd assume the same for anyone's computer. If it's of any interest to anyone, I've got a Creative X-Fi card.

Why does it happen?

I could very well be wrong, but this is my understanding.

Pretty much any PSU I've pulled apart will have the AC Mains earth connected to the case chassis. This, along with anything else earthing to the chassis directly, but the PSU especially I would imagine, results in electrical noise/whatever to be present in the case chassis, which finds its way into the audio circuit, which results in audible noise. Furthermore, being connected to the earthing provided by the mains wiring in your house, anything else plugged in (appliances, electrical equipment etc) will add to the electrical noise on this circuit. Old/bad wiring, dodgy appliances and other things with a heavy power draw may worsen the issue. Really, everyone is going to experience something different depending on the environment where their computer is used.

Here's an experiment to help you understand. You've probably all already done it at some point without even realising. You'll need some speakers, with a built-in amplifier - anything that requires a plug from the wall should do the trick. Plug in a 3.5mm lead or RCAs, whatever it takes, and turn them up a bit. Normally you'd connect the other end to an audio source, be it a computer, mp3 player, etc. Sound goes along the wire in the form of electricity and everything works. Instead of plugging it into an audio source however, take the other end of the lead when plugged into the speakers, and touch the bare ends of the plug with your finger. Wetting your fingertip on your tongue will help. In the case of a 3.5mm plug, you've got the plug split into 3 partitions (Left, Right and Ground). The human body has a bit of electrical charge, and this will be received by the speakers and played as an audible buzzing noise.

Basically the same thing is happening. There's surplus electricity present in the case chassis looking for somewhere to go, so it goes in reverse - through the jack, then the headphones, and earths via the sound card - a complete circuit with a small current flowing across it, creating the annoying noise we hear. Thus the solution: Simply break this path!

Given audio leads/sound cards have their own grounds, it is not necessary to ground directly to the chassis. Therefore we can remove the additional earth, and rely solely on the grounding provided by the soundcard, and everything works sweet.

Hopefully a little understanding and some insight into how to check it will better help people with varying cases determine if the above solution is a viable fix or not.

[fabricator]

Originally Posted by Rake

So again in essence the jacks have 2 earths - one wire that runs to the sound card, and antec's bright idea that runs to the chassis. The latter is causing our interference problems, so all we gotta do is cut this orange wire to isolate the jacks.

The technical term for this is an Earth Loop, the two different earths are at slightly different potentials (read voltages), and the loop behaves as a sort of antenna to outside noise.

Depending on the setup, others may need to cut circuit traces, or use insulating washers under screws. Check there aren't earth connections between the USB and audio ports, that could cause the same problem.

[dazzawul]

parent's comp's antec 900 does that, I figured it was just dodgy onboard... thanks for the heads up yo

[terrastrife]

get a real case.

my nsk3480 doesnt do this, heck its even got an earthing lead from the front panel too

i was quite shocked, as my lian li does have some interference noise.

im no techy but it works lol

[kripz]

I've had this problem for a long time. I've decided to just completely unplug the USB header, maybe its time to revive my thread with this (i think) new knowledge

http://forums.overclockers.com.au/sh...d.php?t=804700

[Rake]

Originally Posted by fabricator

The technical term for this is an Earth Loop, the two different earths are at slightly different potentials (read voltages), and the loop behaves as a sort of antenna to outside noise.

Depending on the setup, others may need to cut circuit traces, or use insulating washers under screws. Check there aren't earth connections between the USB and audio ports, that could cause the same problem.

Nice info

This had the ground lead linking the case, the USB ports, and the Audio jacks all together. As you've probably gathered, I left the USB headers joined to this earth, isolating only the audio jacks.

Originally Posted by terrastrife

get a real case.

my nsk3480 doesnt do this, heck its even got an earthing lead from the front panel too

I've got two of these cases. :P Well, one is the short stumpy 3480 I think, and another of the same but in a slightly larger form. But I never used the front audio ports on them so I don't know what the go is.

Originally Posted by kripz

I've had this problem for a long time. I've decided to just completely unplug the USB header, maybe its time to revive my thread with this (i think) new knowledge

http://forums.overclockers.com.au/sh...d.php?t=804700

Good luck! Yours is obviously a little trickier as everything is on a pcb.. you might need to make-and-break some of the tracks on that board. I'd offer a little more detail but the pictures are too small and blurry.

[Flecktone]

This is a common audio problem. for more information see:

http://www.soundonsound.com/sos/aug0...s/qa0806_4.htm

&

http://www.jaycar.com.au/images_uploaded/humloop.pdf




I've worked as a sound engi for a fixed installation theatre before, and what you'll find is that audio equipment has a separate ground to the rest of equipment.
This is especially a problem when lighting is used on the same circuit as sound equipment.
Lighting equipment creates a crapload of electrical noise which (unless isolated) will feed back into the audio system.

[Rake]

Nice info there!

It's kinda funny to see all the tech knowledge finally meeting those experiencing the issues with no clue why or how to fix it.. It would seem like the two groups of and "duh" were never introduced!

[edzknows]

I have the same problem, i figured it was dodgy onboard too.

Now time to fix it.

Thank you

Edit:
hmm coundnt find any wires to remove, so i made a crude insulation instead.
Im not sure if this is removing the earthing for the USB's as rake mentioned, but its not necessary?
On my case the front audio/usb is in a small metal box, screwed to the chassis.
i unscrewed this and volia, no interferance.
So i unscrewed this and sticky taped the area it sat on, and also the box itself(insulating it from the chassis).
Then i had to find an alternative to screws(as they would conduct).
So out came the cable ties.
poke one through each screw hole from the inside, join a 2nd tie to each and tighten, and trim.
little more wobble then screws, but it works.

Any feedback?

[Rake]

Sorry for delayed response

Hmmm .. obviously the body of the 3.5mm jack must ground to its housing in some capacity. Perhaps they contact directly and not via a wire. The housing on my case's thingimabob is plastic. Are you looking to install things the normal way (screws etc)? I probably wouldn't want to use cableties etc as a permanent solution, esp if it caused things to be loose or whatever..

In any case, breaking the earth path fixed it, so you know what to do..

What kind of feedback you looking for?

[fabricator]

You can get insulating washers, some cases come with them for mounting the motherboard (not needed anyway most of the time). You can also make your own out of any sort of plastic material.

Anyway point is to have to insulating washers, one either side of the board. This way its insulated from the screw.