okay audiophiles..need help with speaker humm

[allsighs]

Okay. Starting yesterday I started to get a low, but noticeable humm coming from my speakers. I have not loaded any new drivers or programs. i am working on an Nforce2 mobo using onboard sound with 2.0 logitech speakers. I have updated the audio driver....still there. I unplugged the jack and powercord incase they werent sufficiently grounded...still there. Im running out of ideas. One item of note is that if there is something bright "like white or yellow" on my TV screen, the humm is louder.

Any other things is can troubleshoot?

[KingArgyle]

Sounds like you are picking up some rf interference or have somebody in your neighborhood with a very powerful amateur radio system. I used to pickup a neighbor that had an amateur radio system from time to time on my desktop speakers.

The only other time I had a low hum constantly coming from a speaker when no audio signals were going to it, was when the amplifier in my powered subwoofer started going bad.

[capone]

You can get an FM trap to try to get rid of some outside interference. It could be your cabels are thin and crossing over power cords, too. Other than that, you may have something creating some loopback. I remember we had this old stereo in college that ate speakers because one would lose connection and it would send an extra signal to the other.

[drain]

One item of note is that if there is something bright "like white or yellow" on my TV screen, the humm is louder.

Do you have any audio cables running close to the TV? It sounds like you are getting some pickup from either the TV tube itself (it is a CRT, not LCD or plasma, right?) or from the video signal. Try moving or reorganising you cables.

[Kevl]

bright colours on the screen are correlated with a high amplitude video signal. Sounds to me like you are picking up video signals on your audio inputs. Are your ausio and video input cable routed together? Try moving them away from each other. If you are using scart leads then make sure the scart leads are pushed home at both ends.

You may also have a simple ground loop.

You need to post more info of what your gear is and how your gear is wired.


Kev

[allsighs]

I have my htpc in my entertainment center about 1 foot under the tv. tv is a 32" crt toshiba. I am running an analogue cable into my tv tuner card. Video is output from svideo out on an ATI 9250 while the audio is handled by the mobo onboard Nforce2 audio out to logitech 2.0 (no subwoofer) speakers. this is a problem that that i have not occurred in this configuration since i set it up about 6 mo ago. The hum just started 1 1/2 weeks ago without any hardware changes.

I figured at first that it was a software issue that would be causing an audio loop, but i had no significant changes and with the screen brightness affecting the hum, i figured it was a grounding issue. The only thing is that we had a power outage around that time, but i have a high joule belkin surge protector so i figured it wasnt that.

Thanks for the responses. It gave me a lot more to think about in trouble shooting.

[nitrogen_widget]

It could just be the on board sound.
I've had two MB's with on board sound create a hum that changed in pitch when I moved the mouse.
Once switching speakers fixed it, the other time I had to put in a doundcard.

Have you tried a sound card?

[Kevl]

check you have muted unused inputs on your soundcard. You might not have changed anything since the hum started but an app you ran may have played with your soundcard settings.

Kev

[aznation]

Did you say that you've already tried a ground loop isolator?