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Noise on amp
#246723 - 02/16/11 08:00 PM
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I have (finally) built myself a little Mame cabinet. I am however having issues with the amplifier I am using. The amp is this 40w one from Maplin (http://www.maplin.co.uk/40w-power-amplifier-module-37737) which I want to run off of the PC supply that supplies the computer too. It works, but when I plug the amp into the soundcard of the computer I get a load of noise out of it (plus the sounds that should be there). It sounds like all the motors within the case are being picked up, I can hear when the HDD accesses, a note change if I slow down the cabinets cooling fan etc. However if I then plug the amp into my MP3 player it is totally clear of any noise.
I am at a loss, how can I get so much unwanted noise from the computer, yet unplug it from the PC and plug it into something else and it is fine.
The only thing I have found on the net is in relation to car amps having a similar issue and them isolating the audio from the headunit to the amp with this black box.
I have the amp wired to the PSU via a molex connector and running off of 12V.
Does anyone have any suggestions?
Many thanks for any assistance you can offer!
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| redk9258 |
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Re: Noise on amp
[Re: smartroad]
#246728 - 02/16/11 09:58 PM
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You may have a ground loop. Try tying everything to a common ground. You might need to put some capacitors inline between the sound card and amp. That is probably what the black box has in it for car stereos. Another thing you can try is to break the ground between the sound card and amp.
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| R. Belmont |
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Re: Noise on amp
[Re: smartroad]
#246801 - 02/17/11 04:13 PM
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> I have the amp wired to the PSU via a molex connector and running off of 12V.
Try running the amp off a separate power supply from the computer and see if that helps.
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Re: Noise on amp
[Re: R. Belmont]
#246830 - 02/17/11 09:20 PM
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> > I have the amp wired to the PSU via a molex connector and running off of 12V.
>
> Try running the amp off a separate power supply from the computer and see if that
> helps.
Aren't sound card's notorious for picking up the noise inside of a pc? Of course I'm going from my memory of when PC Magazine talked about this issue with sound cards back when they use to print the magazine twice a month and had useful product reviews.
Kevin Eshbach
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| redk9258 |
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Re: Noise on amp
[Re: keshbach1]
#246835 - 02/17/11 10:10 PM
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> Aren't sound card's notorious for picking up the noise inside of a pc?
I don't think as bad as they once were. I don't get much noise when I transfer audio (LPs) to my PC.
I used to use a Turtle Beach Santa Cruz sound card, now I just use the on-board sound card on my new motherboard.
Edited by redk9258 (02/17/11 10:11 PM)
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Re: Noise on amp
[Re: krick]
#247081 - 02/20/11 11:23 PM
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> I've attached a diagram for a dc filter circuit from a book that I have.
Cheers, tried it but didn't work 
Decided to abort that idea and change over to a USB powered speaker that I have been using for testing.
Many thanks for all the advise and help guys!
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My Arcade Blog
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Re: Noise on amp
[Re: smartroad]
#247082 - 02/20/11 11:31 PM
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Re: Noise on amp
[Re: krick]
#247083 - 02/21/11 12:39 AM
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