What is the screeching?

May 28, 2012 6:57 PM

Computer/Electronic/AudiophileFilter: I just finished my first build of a computer. When I plug in my computer's onboard sound into my receiver through the standard 3.5mm audio jack and output to two KRK monitors and a sub, I get screeching/scrambling from the speakers that drives me nuts. It basically sounds like I can hear my processor. This doesn't happen with headphones. Lots more inside.

So I just finished my first custom-built computer, and now I run into this annoying problem near the end of it all that has me stumped. After about 36 straight hours of reading instructions and carefully wiring and setting everything up, I run into this audio problem with my onboard sound.

What I have is a Denon AVR-391 receiver, two KRK Rokit 5 studio monitors, and a PolkAudio PSW10 10" subwoofer. On my previous computer (OptiPlex 745, also onboard sound, no problems there), and all other devices I wanted to listen to on this setup, I would just hook up through a 3.5mm-to-2 RCA male jacks into the DVD audio inputs on the receiver and listen away. Well, this computer doesn't seem to like the setup.

I can hear clean, correct audio if I connect my iPod or laptop to the 3.5mm audio cable, which goes to the receiver as an input and outputs to the two KRK monitors and the subwoofer. So by that success, if I connect the motherboard's onboard line-out (green connection) to the same 3.5mm audio cable, I get a screeching/scrambling sound through the KRK monitors. All I can say about the sound is that it sounds like my processor working. If I open a program, I hear the screeching drop slightly, then pick back up when the program is open.

So I then try to send the motherboard's onboard line-out connection to a pair of old Juster speakers and don't hear the screeching at all. Also, if I plug in a pair of headphones, the screeching doesn't exist there either. I've also tried directly connecting the motherboard's line-out directly to the KRK monitor without the receiver in the middle, and it still exists. So it looks like the onboard audio from the motherboard doesn't like any type of connection to the KRK monitors.

I've tried connecting the computer to a different outlet entirely, and one of the monitors on a totally different outlet on the other side of the room to see if there's too much power, or a grounding issue or something going on, but the problem still exists.

I've tried disabling all other audio devices through Windows, as well as all recording/line-in devices, but nothing helps. I've also tried disabling some things in the BIOS such as onboard sound all together on boot up, but that doesn't do anything either. It seems the sound begins as soon as the "Starting Windows..." logo appears on boot-up. Another thing I tried was connecting the 3.5mm audio cable to the front panel's headphone-out and the problem exists there too.

Also, all devices are connected to a 6-outlet Tripp Lite surge strip, and that is connected to a 3-pronged outlet. There are no adapters going on here.





I hate getting into these pickles when I take on a project like this. I've been thinking about buying an S/PDIF cable and using that as the connection from the onboard sound to the receiver seeing if maybe that would help because it's a digital (?) connection, as opposed to the analog (?) connection of the 3.5mm jack. If that doesn't work, I've also thought about just buying a dedicated sound card such as the ASUS XONAR_DX and seeing if I can get away from the onboard audio problem altogether.

I hope this is a common thing with onboard audio and studio monitor speakers (or any speakers), because I really don't want to rip apart the computer again and send the motherboard back. I'm sure the motherboard is okay anyway because everything else seems to be working perfectly. The processor, all RAM, SSD, etc. work flawlessly.

Does anyone have any insight or reasoning as to why this is happening, and do you think my last two options could be problem-solvers? I would really appreciate the help anyone has to offer.

posted by jwmollman to computers & internet (22 answers total)

Hm, nope, it's not a problem common specifically to onboard audio and (any) monitors. I use a tiny but fairly new Mackie 402-VLZ3, which i have running between my Event 20/20 self-powered monitors and my computer's onboard audio. (Not only that, I also have a firewire card running an additional simultaneous external RME Fireface 400 from the same computer for Reaper multitrack recording.)

The Mackie is amazingly quiet, but there's no question that devices in proximity to my rig cause weird noise similar to what you are describing. It's just way way quieter than what I think you're getting.. in my case, I get it from my cable modem & router because they are so dang close to everything else. The audible problem they cause goes away when I physically move them as far from my other stuff as possible.

I do think it would be a worthwhile experiment for you to try either the s/pdif cable or another audio card. Why you're having this problem with the new box vs. the old one, I couldn't say.. I'm definitely not an expert in EMI or grounding issues. ; )
posted by bitterkitten at 7:11 PM on May 28, 2012

So, let me see if I correctly grok your setup

Computer out-> headphones = AOK
Computer out-> audio in on stereo = screaming.

Does the bad setup produce the actual sound you're expected, or a semblance of it, but maybe clipped really badly?

I'm wondering if your stereo equipment is expecting line level and you're pushing driver level output to it.

Does the software volume control make much of a difference, especially at really low levels? Can you e.q. most freuqencies down 40db?
posted by Mad_Carew at 7:39 PM on May 28, 2012

Mad_Carew, yes that is correct. Also, if I just plug the onboard line-out directly to the speaker without the receiver, the screaming persists.

I can hear audio coming through the speakers (music, sound effects), but the screeching drowns out all the other audio. The screeching fluctuates as I use my computer and do processes, so I think it's in sync with my processor's functions. Also, if I watch the seconds on the clock, I notice there's a matching rhythm with the screeching and the advancement of one second on the clock.

When I adjust volumes through Windows it doesn't make a difference. The screeching as a volume of its own.

How could I adjust the line-level option, or even check for it?
posted by jwmollman at 7:49 PM on May 28, 2012

This all just screams "grounding problem" to me. You don't hear it from your headphones because they do not provide another path for the electricity to go to ground.

Is the receiver/monitor grounded? How about the computer? Three prong outlets all the way? Is the motherboard grounded to the chassis? (you used to have to do that - not sure if newer systems need it). Are they behind different surge protection?

Just as an experiment, try using an extra headphone cable and touch your receiver's chassis to your computer's. Does it change the sound?
posted by montag2k at 8:09 PM on May 28, 2012 [3 favorites]

I believe the wall socket is fully grounded. We used to use the 3-prong to 2-prong adapters, but my mother had a guy change them all to 3-pronged outlets.

On one outlet on the wall socket, I have the Denon receiver. On the other socket I have the 6-outlet surge protector that has my LCD display, the two KRK monitors, computer, lamp, and subwoofer.

Also, I am pretty sure the motherboard is grounded to the chassis. I followed all instructions when screwing in the stand-offs. Also, the backplate of the CPU cooler (this) fits kind of tight against the motherboard cut-out in the chassis. They are touching, but I wasn't sure if that could cause something like this.

And I don't know if this is what you meant, but I had the computer connected to the receiver with the 3.5mm cable (screeching occurring), then I took a male-to-male 3.5mm cable to touch the receiver's metal body to the computer's chassis and didn't notice a change in sound from the speaker.
posted by jwmollman at 8:20 PM on May 28, 2012

Here are two off the wall things to test.
1) Make sure the computer power supply switch, if it has one, is in the "120v" position and not 220/240.
2) Related to the grounding. Turn around one of the AC plugs in its outlet. Either the computer AC plug or the receiver AC plug, but not both. Use one of those 2-to-3 adapters if you need to to turn around one plug.
posted by caclwmr4 at 8:23 PM on May 28, 2012

Yeah, I guess I just wanted to see what would happen if you added another path between the receiver and the computer.

So it sounds like the receiver is not behind the surge protector, but the computer is? Did you try to switch the receiver and the lamp yet?

My analog EE skills are pretty rusty, so hopefully someone with a bit more recent training can pipe in if that doesn't work...
posted by montag2k at 8:24 PM on May 28, 2012

caclwmr4, the power supply I have is a Corsair TX650 and it doesn't seem to have a red voltage regulator switch. Also, if it was set in the wrong position, wouldn't the computer not boot (or be destroyed)?

And I don't know if turning them around would even work. The outlets have the one big plug and the one smaller, so I don't know if they would physically fit.



montag2k, I have also tried the receiver on the surge protector with the computer on as well (also with the KRK's on the surge protector). That didn't seem to fix (or change) the sound.

One thing I noticed is that the sound is quieter than it was earlier today, and I'm using the same setup as previously. I did take the computer apart though to re-plug the HD Audio connection from the case to the motherboard, but I'm using connections from the motherboard in the back, so I'm sure that wouldn't have anything to do with it.
posted by jwmollman at 8:30 PM on May 28, 2012

Use a USB audio dongle. They're like $25 and they put the D/A converter outside the electromagnetic hell that is a computer case. Here's one.
posted by kindall at 8:51 PM on May 28, 2012 [1 favorite]

The solution, of course, is to reduce Taiwan to a pile of rubble. But you already knew that. What I mean is that it's likely your motherboard's fault; the analog audio circuitry isn't properly protected from the noise created by the digital circuits inside your computer. It's a common problem with motherboards, but the jokers on PC reviewing sites can't be bothered to test for it.

The optical and digital S/PDIF shouldn't have that problem. Since it's only $5, I'd try that first.
posted by Monday, stony Monday at 9:00 PM on May 28, 2012

Could you provide more information on the specific motherboard and case you're using?

While you said that you disabled other audio and recording devices, have you gone into Control Panel -> Sound and muted any inputs or outputs that aren't in use?

Video cards tend to be the most common culprit with these sorts of issues. Is there any chance that the wiring to one of the audio jacks is touching or running particularly close to a dedicated video card?

That said, an SPDIF connection from your motherboard to the receiver will almost invariably take care of this problem.
posted by eschatfische at 9:21 PM on May 28, 2012 [1 favorite]

Well, if the PS had a switch and it was set for 220 and you're using 120, it would probably still work with no apparent problem, but there would be an extra transformer or something switched in place. (The reverse should blow it.) So this is out anyway.

Even with the one larger prong, you should be able to jam the plug into a rubbery 2-to-3 adapter, as one wild guess is one of your wall outlets is miswired.

But both of these are low priorities, only some fast no-cost things that could be worth a try.
posted by caclwmr4 at 9:35 PM on May 28, 2012

Actually now that I think about it, I don't know if the S/PDIF cable would work, because I just ran another test where I connected the 3.5mm to 2 RCA males from the computer's front audio outputs to the receiver, and then plugged in headphones into the receiver's headphone output and I can now hear the screeching through the headphones through the receiver. Maybe the screeching was there all along, it's just the receiver amplified it and I can hear it more.

eschatfische, I have an Intel DH77EB motherboard, an i5-3450 (using its onboard video), and the Define Mini case.

I have also tried muting, and then disabling all other audio devices through Windows control panel but that didn't do anything for me.

Is it possible how I ran my wiring and cable management could be causing the interference? I ran the cables along the backside similar to this rig.

Also, now when I move my cursor or type on the keyboard, I can hear a different tone of the screech, but I can hear it more detailed through the headphones through the receiver. I can also hear "swooshing" sounds when scrolling through pages. Man, this sucks.
posted by jwmollman at 9:35 PM on May 28, 2012

You should start by making sure you have the latest ALC drivers for the integrated audio chipset installed.

Next, disconnect the HD Audio header for the front audio jack from the motherboard and test exclusively from the jacks on the board itself. If you disconnect the front jack and suddenly everything is fine, either the connection to the front audio jack is inadequately shielded or the case came with a faulty jack.

Then try the SP/DIF cable - this interference, despite being related to activity on the computer, ultimately sounds more like electrical interference than the type of digital noise common to sound card problems, which means that the optical SP/DIF cable would not be affected and would ultimately eliminate the problem.

As a last resort, try a 3 prong to 2 prong adapter when plugging in to your computer, which you can use to experiment with grounding the computer to something other than your mains ground.
posted by eschatfische at 10:15 PM on May 28, 2012

eschatfische, I will do your recommended steps. But also, I wanted to post a link to the sound I'm hearing. I was searching around and came across the term "coil whine", and this sounds like the exact sound I'm hearing through the speakers. The guy in the video has the same power supply as I do also, and I'm beginning to think maybe the power supply could be the culprit?

Here is another video of the sound I am experiencing, but I can only hear this from the speakers.
posted by jwmollman at 10:26 PM on May 28, 2012

Also, I have tried the latest ALC drivers and that didn't fix the issue at all.
posted by jwmollman at 10:27 PM on May 28, 2012

This is a ground loop issue. Radio Shack sells a "ground loop isolator" intended to be used mostly in car stereos. Buy that and try it!
posted by stephennelson at 1:24 AM on May 29, 2012

When you installed your motherboard, did you use metal standoffs in all the screwhole positions? I've had boards that made audible noise like that until all the screwholes were properly grounded. And the screws had to be pretty tight, too. So if you used the nylon standoffs, change them out for the metal ones.

(This could also be a problem with the case, if there isn't a solid path to ground from the motherboard standoffs to the ground prong of the power cord. Sometimes, ground is referred to as "drain" because, like a plumbing system, there needs to be a path to ground for all the "waste" noise to go. If the path to ground from one of the noisy things isn't great, plugging in a grounded audio cable gives it an easier path out. Since the ground is also the negative side of the audio signal in those cables, the fluctuating voltage turns into audio.)

I will also get that noise when I am trying to record audio on one of my laptops. It would only go away if I used the ac adapter, and only if it was the adapter that had a three prong plug.

But yeah, onboard audio circuitry can be a crapshoot. The chips themselves are usually fine, but how they are hooked up on the board can sometimes be non-optimal. I would definitely try the toslink cable. They can solve a myriad of problems. (And improve sound quality if your receiver has a good D/A converter.)

(Linked video of power supply whining: that sounds very much like there is a bad filter capacitor somewhere in the P/S.
posted by gjc at 6:15 AM on May 29, 2012

2) Related to the grounding. Turn around one of the AC plugs in its outlet. Either the computer AC plug or the receiver AC plug, but not both. Use one of those 2-to-3 adapters if you need to to turn around one plug.

With polarized plugs, this shouldn't be an issue. However, if one of your devices has an unpolarized plug somewhere along the way, it could be. Do not switch polarities on things with polarized plugs, the devices may not be expecting that.
posted by gjc at 6:18 AM on May 29, 2012

Your description of hearing the seconds change on the clock may be a hint as to the cause. Computers don't typically rely on spans of time as large as seconds, so what you may be hearing is the display being drawn. Do you hear the sound with the computer monitor off? Is your display cable shielded? It should be fairly thick (more than a quarter of an inch or so) and should have ferrite beads near each end. Keep the display separated from the audio cable to minimize interference.
posted by borkencode at 11:53 AM on May 29, 2012

gjc, I did use all eight metal standoffs that the motherboard instructions told me to use. These were the standoffs I used. I didn't want to tighten the life out of the screws because I didn't want to warp the motherboard based on the issue I mentioned earllier -- the backplate of the CPU cooler touches the motherboard cutout in the chassis. I was afraid if I screwed everything down too tight, it might bend the board and damage it over time. I did tighten them snug though, but now extremely tight.

One thing I noticed about the Define Mini case is it has soft "bumpers" where the power supply sits I guess to absorb shock to the power supply. It feels like a foam of some sort. Maybe the cushioning could cause the draining?

I just purchased the TOSLINK cable so I'll see how that goes. If that doesn't work, I can always try one of those ground loop isolators as well. If I bought a sound card, would that solve the problem? I'm thinking if maybe the onboard audio doesn't have a safe way out, maybe if I used a dedicated sound card to output my audio, I would be getting my sound through a different piece of hardware. So maybe the noise would always exist on the onboard audio side, but I wouldn't be hearing it because I would be using a different sound output source instead.


borkencode, I am using the standard DVI cable that came with my monitor. It looks like this, but when I had this monitor hooked up to a different computer over DVI, I didn't experience this problem. I think the cable should be fine. I also hear the sound with the monitor off. I've tried turning off both the monitor and the lamp on the desk but that didn't eliminate the sound.
posted by jwmollman at 12:03 PM on May 29, 2012

If I bought a sound card, would that solve the problem?

This is exactly what I recommended a couple days ago. Not a sound card, but a USB audio output. The whole audio circuitry is outside the computer, so much less potential for interference. As a bonus, the USB dongle may be louder than your built-in audio.
posted by kindall at 4:19 PM on May 30, 2012