I have a PC-based recording studio with a very specific problem. I am getting a sort of scratching noise through the speakers when I move the mouse, load software or scroll web pages. It seems like it is coming from the motherboard, but I can't tell for sure. I changed hard drives and sound cards and it still exists. I'm using the on-board video controller, so I haven't yet eliminated it as a suspect. Other people have described having the same problem and it was most noticable for them when they had a laptop plugged into a PA system. They could hear the scratching sound when they moved the mouse. Anyone familiar with this?

My gear:
AMD 1.3Ghz Athlon
XP Pro SP2
On-board S3 Savage video
256MB RAM (I have to get more, I know)
40GB HD
Logitech trackball mouse
Micro Advantage 52x32x52 CDRW
Sound Blaster Audigy
External mixing board running Event TR5 powered reference monitors

Essentially, this is a HP Pavilion 7935, but I've replaced the original CDRW, HD and power supply. The only original parts left are the motherboard, CPU and floppy dirve (and I never use floppies, anyway). I should probably go ahead and replace the motherboard and get a good video card, but I wanted to see if anyone knew of anything I could do otherwise.

First...Check to make sure there aren't any products within the computers range that could be causing some sort of interference... Second check the fan for possible things stuck inside it....

If that doesn't work try replacing the mother board but first get a second opinion

Also...Have you noticed any slowdownage of your computer...Could be a virus making your computer have to use more processes then it should... But it sounds like a CD-ROM problem...Try taking all disks out of the computer and then restarting it?

Thanks for the reply, spacewaste.

I've moved things around and tried isolating the comupter. The interference does not seem to be from an external source. I blew the dust out of the fan and that didn't change anything, but it needed to be done anyway.

I've done all the virus, spyware and adware scanning there possible. My system is really clean. I even did scandisk, defrag and ran Eraser to maximize empty space. I only put CDs in the drive when I'm using them and never leave any in there, so that's not the problem.

It may be the motherboard, or at least the on board S3 video controller. I still want opinions, though.

If anyone has ever heard a scracthing sound come through their speakers as they moved their mouse and found a way to get rid of it, please let me know!

Hmm....I've thought this through...and it may be the speakers themselves?...It seem that that or the mother board is the problem...Try plugging in a different set of speakers to test it out?

I've tried different speakers. The speakers I'm using are super-clean Event Tuned Reference studio monitors. They aren't nearly the best monitors out there, but they so good that they make it possible for me to hear the problem.

I don't think the noise is bleeding onto any tracks I'm recording because I've listened to my mixes in another studio. It's like the noise is not in the input section of the signal and is only being picked up by the output section.

this is definatly interferance.... make sure the audio wire funning from the pc to the speakers goes nowhere neer the mouse wire, or monitor wire (or monitor), and possably network cable (however network cable interferance should be out of hearing range)

The interfereance is only effecting yoyr speakers, so for exampkle burning an audiop cd, the sound will be perfect.

if you cannot get enough distance between your audio wire, and sources of interfereance, look into using shielded wire (like coax). not sure f you can buy it, but if you own a soldering iron, its nothing complicated.

You may not be able to remedy your problem in a conventional manner.

There is too much interference generated in a computer to really get clean audio from a regular sound card. I periodically reinstall my sound card drivers to get a better sound as the quality deteriorates over a period of time. If you could shield your sound card in a metal housing and get a clean ground also grounding the housing it will do the trick.

But here is something you can try that takes the audio from your usb port as digital audio and convert it to analog. They have box for about $150.00 bucks that seem to be popular.
http://www.stereo-link.com

Good luck!

however it is worth noting that USB sound or a metal em shiled around your sound card will not effect the quality of audio that your computer exports as a file... only what comes through your speakers.

for me, the interfereance was completely in the cable to the speakers, not the sound card, however it could be a great home project shilding your sound card.

look up Farraday Cage (and ive probably spelled that wrong)

Thanks, Rudy. The stereo-link is a good recommendation, but I think if I went with a converter, I'd want it not just for output, but input as well. I'd like to go that far but can't just yet. I've been drooling over the high-end gear that will do the job.

Hey, qwijibow! Your idea is full of possibilities. An ideal Faraday Cage would be difficult because of the audio connectors on the card that go to an external box and CD player. A more simple sheilding effort may do the trick, though. I'm not sure how exactly to this this so I'll have to do some research. Any suggestions on materials?

You were also right about some of the noise coming from a poorly shielded cable! I identified a culprit as an RCA to RCA running from the Tape Out of my mixer to a Line In on the Audigy. I switched it out with an RCA to 1/8" going directly to the soundcard and eliminated half of the noise! I have higher quality RCA to 1/8" cables on the way to me right now and will switch both the Tape In and Tape Out to new, better cables. If any noise still exists, I'm going to start working on shielding the sound card.

Thanks again!

Generally the scratching noise came from magnetic fields, the magnetic fields inside of computer are the ventilators and transformers (power source, cpu fan, vga fan or tower fan). Try with another power source, generally the noise come from there, don't buy a cheap one, buy something like thermaltake (www.thermaltake.com) or kindly, they are pretty expensive but you get quality, i've one and is great, you can select the fans speeds (for noise) and they also have PFC (Power Factor Correction) you can save some money saving power.
Like I said check the fans (cpu, vga, tower) maybe the noise came from there.

Greets
Deivid