mic buzzing - software fix - wtf?

M

Momo

Gawd
Joined
Mar 3, 2005
Messages
869
Okay so i'd like some clarification here. I thought i had electrical noise being picked up by my mic. My Xonar is being replaced by asus, apparently they found something wrong with it... im using the onboard audio now (gigabyte gaming 7). The buzz WAS gone. It reappeared a couple days ago, after a number of days gone with onboard in use.

So i'm like WTF?!. I thought it might be a crap ground, so i tried experimenting a bit. Unplugged the UPS from the wall, the buzz gets signifigantly quieter but is still there. I tried taking the computer upstairs, completely different area of the house and plugged it in, with nothing else hooked up aside from headphones. The buzz is there, it's just a lot quieter.

So i went back downstairs, and checked out the crystalvoice suite in the creative software. Turned it on, and ticked 'noise correction' and the buzz disappears completely.


Am i correct in saying that software cannot get rid of electrical noise?


This almost certainly has to be a noise being picked up by my headset's mic (beyerdynamic MMX-300) in my environment, eh? i've got the mic volume max'd, and mic boost to +30db. If i set it to 0db, i'm super quiet and the buzz is still there, just quieter (without noise correction obviously).

... my next step is to turn everything else i can off in the room, and try 'listening' to the mic without noise correction on. Wondering if the laptop cooler i'm using to help cool my set-top box is being picked up, for example. ... I'd like to use the Xonar when it's replacement returns, can't remember if it has a noise correction feature. it probably does, and i probably tried it without any luck.
 
Software can get rid of any sort of noise. I mean software can get rid of any sound at all from a digital signal. It's simple DSP work. The only issue is figuring out which frequency bands your "noise" is in, or what the general sound signature of it is. Subtracting "noise" from signals is trivial for computers of today, supposing they can recognize what the noise is. In your case, suppose you let the mic simple sit idle without you saying anything. All the computer has to do is an FFT of the signal that's present without you saying anything, and then attenuate those frequency bands a bit. It's probably something like a triangular wave or something of the sort, which means it has a pretty standard set of frequencies in which it operates, and most of that is concentrated in a specific band (the other harmonics are much attenuated compared to it). Now, I'm not 100% sure if that's what modern noise cancellation implementations do, but again it's not really a big deal for software to get rid of noise, supposing it has some idea of what the noise is. Considering how long the FFT has been around, we probably have it down to an art at this point...

Edit: I want to clarify that this is supposing that:
1. The digital section of your system doesn't have noise (if it did, it would have random bit flips which would by the way generally be catastrophic, so yeah probably not an issue)
2. Your headset itself doesn't have noise from the output line. If it does, no software can't do anything with that.
 
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Hey thanks for taking the time.

The headphone portion of my headset has no noise at all. Dead quiet.
Only when the mic is open / set to 'listen to this device' do i hear the buzzing. It's not a very high frequency, sounds like a tattoo gun almost.
One thing i don't get... if i touch the mic's foam, it gets much worse. If i touch the side of my computer case, it reduces it significantly.
I was messing around with fans, unplugging them etc. When i touched the fan pins it reduced it significantly. This lead me to believe it might be a ground issue. I'm NOT an electrical person, or a sound tech, so bear with me :)

edit: yes, i've tried another headset, same issue. my headset on a pc that doesnt have the problem, no issue.
 
It's not really noise reduction, it's signal reduction. Aside from the buzz, your voice and ambience sounds much clearer with the noise reduction _off_.
Especially the higher notes like clicks - I can barely understand you with noise reduction _on_.
It's a band-aid on a gunshot wound.
The real issue is in the circuitry of the whole setup - as you suspect yourself.
You were very sensible in breaking the problem down by using another computer and another headset during the testing. It's the mobo or the PSU.
The microphone is picking up stray signal from the headphone, which plays it, which feeds back into the microphone, which passes it into the headphone - and so on.

Now comes the fun part...
You get to do all sorts of weird seemingly unrelated shit until you begin to hallucinate the buzzing!
In order of least annoying to most:
- disconnect the front panel audio jacks
- unplug and re-seat any and all wires leading to friggin everywhere. With the mobo power plug - for example - try to slightly push the individual wires down after you fasten the connector. Same for molex.
- pick the motherboard up just enough to remove the back IO shield - try running without it.
- remove mobo from case, place it on a non-conductive surface (NOT the anti static bag) and basically see if it happens with a minimalistic setup
 
thanks for the reply Michalrz.

Yeah, i was trying to avoid your last two points there.
I haven't actually re-done all the PSU connections, but i figure that is the next thing i'll try (once i've removed the dedicated graphics card and extra HDD's & optical drive, tried the system, and assuming there's still a buzz).

I'm very tempted to leave everything as it stands now and just try a different PSU (sitting it beside the case on a plastic mat should work i wager) ... if the buzz is still there, i guess it's time to take apart the entire system, and power it up outside of the case with absolutely minimal components like the above.
 
try a ferrite choke/filter. as silly as it sounds, turn off all the lights in the house. it could be picking up florescent lights if you have any, even CFLs.
 
Yes, I did have an USB DAC that would go into stupid when someone turned the CCFL lights on.

Also, try a cheap USB audio card first. They cost very little, many are built into USB plug speakers...

Edit: try disabling C1E, Speedstep and all power saving features in CMOS setup. Set power profile to 11 in Windows.
 
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Re bios settings...
Happened to google "CPU spread spectrum" yesterday and it's to reduce EMI. Try that too.
 
I noticed that if you use Creative noise cancellation feature, that introduces a constant hiss / crackling background noise. Try yours without the background cancellation etc. options on.
 
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