digital noise?

[gurumonkey]

I have my computer hooked up to a sound board. problem is, i am getting a bunch of digital noise (processor sounding type stuff) coming through the audio feed. What's the best way to deal with this?

[monolake]

Step 1: Tell the people here some facts: What computer? Which OS? What sound-card? Which inputs / outputs connected and to which other equipment? Does the noise change if you open an audio application etc... etc....

We are nerds, but we are not oracles. Mostly.

Robert

[gurumonkey]

It's a dell laptop, running windows xp home edition i think. The sound card is an m-audio fast track pro. i have one aux send from a yahama 01v96 running into the input of the fast track pro so that i can record from the board. I also had one cable running from the output of the sound card to an empty slot in the board to hear how it sounded. The sound isn't constant, but frequent. It seems as though the noise will always be present when the computer is using more cpu, so yes, opening a program would increase the noise. I figured it was probably related to power, that's why i didn't post all of this stuff.

[monolake]

Hmm. Well, i would disconnect all I/0 from the sound card and check if the sound is clean using headphones. If there is still a problem, check the latency settings of the audio driver, and set it higher than what it is now. If disconnecting all I/O stuff does solve the problem, step by step reconnect. Are you also using the digital inputs / outputs? It could be a sync problem then. Check who is the master clock, and who runs as a slave. Etc....

Robert

[gurumonkey]

all the ins and outs are analouge. I'll do a little troubleshooting.

[crumhorn]

My money's on multiple paths to ground.

Code: Select all

+----+   USB Cable   +------------+  Audio Cable  +------------+
| PC |-------------->| Sound Card |-------------->| Other Gear |
|    |               |     |      |               |            |
| +--|<--------------|-----X------|<--------------| ----+      |
+-|--+    Screen     +------------+     Screen    +-----|------+
  |                                                     |
  +-----------------------------------------------------+
                       Mains Earth

The current in the USB cable should all return via the cable screen but in practice the current splits at point X and some of it flows down the screen of the audio cable through the other gear and back to the PC via the mains earth.

Using a top quality USB cable and connectors can help. The lower the resistance of the cable the les current will go the "wrong" way.

Using top quality audio cables and connectors can also help. Low resistance cables will reduce the size of the noise signal seen at the input of the audio gear.

Balanced connections can also help because voltages on the screen should be rejected.

[Plastic Hassle]

Record it, burn it, send it to Editions Mego and wait for the $s to roll in

[Earwax69]

One of my cheap ass pc do that, you can ear the processor doing weird noise through the headphones. They say its because the cheap soundcard is near the cpu and the electric cables are not well isolated.

But here you dont use the onboard sound card, you use a M-audio... I really dont know what is causing this.

I would recommand to update to the last drivers. I fixed one similar issue like that. Not only for your m-audio but for your onboard card too. realtek or sigmatel... whatever it is.

[Dennis DeSantis]

Almost certainly a ground loop.

Do you live in a country in which the ground on your laptop's power supply can be easily (and legally) defeated? In the US, for example, there are 3-to-2 prong adapters which defeat the ground. This almost always fixes these types of noise problems (which are notorious in Dell laptops.) If you do choose to tamper with your power supply, proceed at your own risk...

Another solution would be to run the audio outputs into direct boxes with ground lift switches.

Good luck,

[cotdagoo]

You can pickup a ground loop isolator at radioshack for roughly $16us - http://www.radioshack.com/product/index ... Id=2062214

[leedsquietman]

I agree with Dennis about the possibility of a ground loop.

However, I've owned 3 Dell laptops including the XPS1530 on which I am responding to this message with and have NEVER had any problems with groundloops or internal computer noise, nor did I on the 5 desktops by Dell which I've owned. So my experience with Dell has actually been fine and this type of thing can occur on any type of machine under certain conditions.

Having a good power source helps. If your computer is plugged into a multi point adapter with no filtering, it can be a common problem, as can interference from other Radio Frequency generating, such as from TVs, DVDs, power lines, Ham/CB/GMRS radios etc.