Speaker Noise

[Stingray]

I got my cab in a semi working state last night. This was the first chance that I've had to see how my speakers work. They're picking up some kind of interference, it seems to be happening when the hard drive is seeking. When you hear the HD doing it's thing, I'm getting a high pitched whining/ beeping sound through the speakers.  



I desoldered the volume knob off the board and have relocated it to a metal plate which will be mounted in the top of the cab so I can adjust the volume as needed. I strongly suspect that the wires running between the volume knob and the board are what is picking up this interference. Is there some way they could be shielded or am I totally barking up the wrong tree?

-S

[Brad Lee]

Simple thing to check would be in the volume properties, make sure that line-in, mic etc are muted, everything except your main volume and whatever it calls wav out

My mobo had a nasty humm that this was the culprit, except it increased on mouse movements instead of disk access like you mention

[Ken Layton]

It's never a good idea to have audio lines hear the fluorescent light fixture. The ballast radiates hum.

At the very least your wire should be two conductor, foil shield, with drain wire. Then the volume control should be enclosed in a metal box if you run near the light fixture.

[Stingray]

Ken, that's good to know, but at the moment, the light fixture isn't wired in at all.

Brad, this is a Mac, not Windows. I'll check the sound control panel to see if there's something similar.

Thanks

-S

[CM]

In amplified speakers, try turning the line level from the PC down very low and then raise the volume on the speakers themselves.  This will help reduce noise picked up from hd/mobo/etc.

[Stingray]

Excellent suggestion! I belive that the line level out is currently set at maximum. I'll give that a shot first thing when I get home.

-S

[menace]

Mine were running off the same pc +5V power supply as the hard drive and made that squealing noise--could be the same thing?  can you isolate them electrically within your cab?

[Stingray]

I did try plugging them into another outlet (not the one the computer is plugged into, but that didn't make any difference.

-S

[fredster]

There are some setting recommendations for sound in the Mame32 troubleshooting guide.  The PC may be bogged down when it's seeking.  Check the Mame FAQ's for something that looks right.

[Stingray]

Again, this is a Mac, not a Windows PC. I'm using MacMAME, but I'll check the faq and see if there is similar troubleshooting info.

-S

[Witchboard]

Well, if you find yourself at a loss, I guess you could always try an inline filter like the guys that run car stereos use to get rid of the alternator noise.  I'm not too familiar with this, but I had some friends that were.  It could be an alternative if you can't figure out the problem in the end.

[Stingray]

That occured to me last night. I'm hoping to find an easier (read as cheaper) solution though. I may try that if all else fails.

-S

[Witchboard]

I can understand that.  Besides, it's always better to try to fix the problem before hiding it.

[Stingray]

In amplified speakers, try turning the line level from the PC down very low and then raise the volume on the speakers themselves.  This will help reduce noise picked up from hd/mobo/etc.

That did it. I have to admit that I probably wouldn't have thought of that. Thanks!

-S