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Old 25th February 2006, 07:55 PM   #1
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Default Help with noise

I recently bulit a chipamp (form Brian Bell) and the thing has absolutely surpassed my expectations of quality and power. The problem is with my soundcard. I get a buzz/hum only when using the PC as a source. No one else notices it, nor does it effect the enjoyment of listening. But, I know it's there and it bugs me. I have made all the standard ground loop test and subsituded sources and cables to come to the conclusion that the noise is generated from the soundcard it's self.

I downloaded a "freebe" analizer and found that with everything muted, the card is generating a 66hz signal at about .18 volts. This is a CHEAP built in soundcard but is the buzz a result of the switching power supply?

Would a quality soundcard help or would I still get the buzz because of the power supply? How bout a USB sound card with it's own separate PSU?

Thank you in advance for sharring in knowledge or experience.
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Old 25th February 2006, 11:32 PM   #2
Bazukaz is offline Bazukaz  Lithuania
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Switching power supplies usually work in the range of 30-50kHz.
Normally , PC sound cards don't generate noise.Try plugging in headphones.If the problem persists , buy a new sound card.
I would't go for a USB sound card.Its quality may be questionable , especially if it is cheap.
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Old 26th February 2006, 12:03 AM   #3
Eva is offline Eva  Spain
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This 66Hz signal is the vertical retrace of your monitor

It may be picked up in several ways, though. It may be coming either from your monitor or from your video card, so the first test to perform is to check whether the noise persists with the monitor turned off and/or with the VGA cable unplugged.

Tell us your findings.
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Old 26th February 2006, 12:11 AM   #4
Bazukaz is offline Bazukaz  Lithuania
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One more advice : try mutting all inputs , especially mic.
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Old 26th February 2006, 12:50 AM   #5
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Eva

Tried with monitor off and with video disco'd. Still got the hum. The video card has a fan on it. Could that be the cause?


Bazukas

Everything is muted.

The hum doesn't start until the sound card is activated.

The hum is not that prominate and wouldn't even bother me so much if the amp wasn't perfectly silent with no input or with a stand alone cd player. But, I built it for my PC.

Thanks for the suggestions. Any more would be greatly appreciated.
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Old 26th February 2006, 01:14 AM   #6
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have you muted the microphone and line inputs as well? as all the other inputs. it might be monitoring an input thats not even copnnected to anything.
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Old 26th February 2006, 01:19 AM   #7
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Everything is muted.

Only thing pluged into soundcard is the amp. Everything including master volume is muted. The hum starts when the soundcard is activated at boot up with everything muted.

The sound card is a cheap AC97 chip on board the MB.
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Old 26th February 2006, 01:48 AM   #8
Bazukaz is offline Bazukaz  Lithuania
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Driver probem ?
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Old 26th February 2006, 02:00 AM   #9
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not driver problem. the noise happens right on boot. could be 66hz is measured by the software instead of 60 because of the steps of resolution in the software..maybe ther eis no 60 and 66 is the closest one.

it may be "good enough" by the motherboard designer and nothing you can do about it.
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Old 26th February 2006, 08:08 AM   #10
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Well in my experiences with onboard sound, you can hear the mouse making sounds in your speakers when you move it, and you hear different sounds as the computer processes. My PC with a soundblaster 5.1 is fine, but my brother's PC with onboard sound, you can hear little noises when you move the mouse, and my computer did the same thing with onboard sound before I got my soundblaster.

Onboard sound is C R A P and picks up all the noise from signals generated in the motherboard, which gets sent to your amplified speakers.

Get a soundcard if you want to use your computer for playing with audio.
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