Strange noises

  • Thread starter Thread starter slipmip
  • Start date Start date
S

slipmip

New member
OK I running an HP dv1000 laptop as my daw. Previously i was just using
the headphone out of the onboard sound card to play audio back. While doing
this i noticed strange noises when i played back at high volumes. The noises seemed to be coming from the operation of the computer, eg minimizing and maximizing a window makes a zapping sound. I figured that the noise was a result of the crappy on board sound card not being properly grounded. But now i
just received and started using a usb interface (cheapo behringer) and I am getting the same noise. Is my computer just lame or is there a way to fix this?
thanks
 
slipmip said:
OK I running an HP dv1000 laptop as my daw. Previously i was just using
the headphone out of the onboard sound card to play audio back. While doing
this i noticed strange noises when i played back at high volumes. The noises seemed to be coming from the operation of the computer, eg minimizing and maximizing a window makes a zapping sound. I figured that the noise was a result of the crappy on board sound card not being properly grounded. But now i
just received and started using a usb interface (cheapo behringer) and I am getting the same noise. Is my computer just lame or is there a way to fix this?
thanks
Click to expand...
You say this happens when you are minimizing a window? does it happen any other time. Is it possible that there are sound effects atributed to operations on your computer? sounds like it to me
 
no, sounds are turned off i windows, the sounds are the result of bad grounding me thinks.
thanks
 
could be a grounding thing, or it could be an interrupt issue between the video/audio cards.
This happens occasionally. I'm guessing you're using on-baord usb ports?
if possible, move your video card to another slot. Otherwise, try and alter the settings for your vid card/usb drivers in the windows hardware setup.

Also, install the latest drivers for both you video card AND your usb ports (yes, USB ports have drivers too- usually bundled with your mobo dirvers)

If you can't do that, consider getting a USB card- they're not all that much, and you have the option of moving it around inside your box to find a slot that doesn't have an interrupt issue iwht another device.

Crud
 
is this a CRT monitor? it could be radio wave interferrance as CRT's will broadcast for quite a ways...

take a small radio and switch it to an AM freq with lots of static and lean the antenna against the screen.. do the min/max of windows and see if it sounds similar...
 
He has a LapTop so there are No PCI Cards and No CRT Monitors or Video Cards ect, none of that stuff will help him Me thinks....
 
Just played a show last week and ran right off the battery. That seemed to keep any strange static noises to a minimum. I also got a tip that using a 2 prong adaptor on the power supply might work, but that kind of bothers me. I suppose it really would be best to just find a correctly grunded outlet, but that would be to easy. thanks for the input.
peace
 
slipmip said:
Just played a show last week and ran right off the battery. That seemed to keep any strange static noises to a minimum. I also got a tip that using a 2 prong adaptor on the power supply might work, but that kind of bothers me. I suppose it really would be best to just find a correctly grunded outlet, but that would be to easy. thanks for the input.
peace
Click to expand...

Bad idea to use one of those adapters. Your outlet is probably grounded just fine, but your computer's power supply probably isn't.

The noise you are hearing is almost certainly caused by the GPU generating noise on your computer's ground plane (and power plane) which isn't being properly shunted to the earth ground because your computer's power supply isn't grounded well enough. My old (first generation) PowerMac G5 had the same problem.

Best way to cure this is probably to actually ground the system properly. Take a three-prong power plug, fasten about a 10 AWG stranded wire to the ground. Make sure you connect it to the right pin!

Fasten the other end of the wire to the shield on an audio plug and connect it to a spare jack on your audio interface. If you don't have a spare jack, build yourself a short extension cable with a plug and jack and tie the extra ground wire into the shield on that. Plug the opposite end of the wire into a spare power outlet.

In all likelihood, the noise will vanish after that. My guess is that the reason that running on battery works is that you are probably running the GPU at a lower core voltage while on battery, but there's another possibility that's even more bizarre.

Most of this noise is on the hot side of the circuit---basically, the 5v PSU output line. When you run on a power supply, the charge circuit is engaged. You now have... possibly a pair of diodes in the power supply's FWB, possibly a transformer, possibly something else entirely... but either way, you now have a very low resistance path between hot and ground.

Audio interfaces are designed to be immune to tons of noise on the hot side. When they get noise up their ground plane, they misbehave almost universally. Since here is probably only a modest resistance between the signal ground and the signal input in your audio interface, some of that noise will leak into the input.

At least I -think- this is what happens. Either way, ground bussing does generally help, in my experience.
 
Last edited:
for what it's worth, when my teachers play movies for the class to view on their laptops and hook up the sound to the speakers in the classroom, when they run the laptop with it plugged into an outlet, there is a lot of background static-ish noise, but when they unplug the laptop and run it off the battery, the noise disappears. Try running the laptop off the battery and see if that helps.
 
You must log in or register to reply here.
Back
Top