My Nucore Installation - Ground Loop Noise Solution

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applejuice
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My Nucore Installation - Ground Loop Noise Solution

Post by applejuice » Fri Apr 02, 2010 11:14 am

Today found something pretty neat to do with removing ground loop noise issue when using original audio amp and single psu

Bought a car audio ground loop filter and connected in between signal cable from motherboard to audio amp. No nasty noise anymore and no need to install second psu.
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Jim

http://tournament.mypinballs.com

"All parts should go together without forcing. Remember the parts you are reassembling were disassembled by you. If you can’t get them together again, there must be a reason. Do not use a hammer." ~ IBM

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Chuck
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Re: My Nucore Installation - Ground Loop Noise Solution

Post by Chuck » Fri Apr 02, 2010 1:30 pm

Very cool. How much was it and where did you get it?

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dweingarden
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Re: My Nucore Installation - Ground Loop Noise Solution

Post by dweingarden » Fri Apr 02, 2010 9:10 pm

When I designed our audio amp, I struggled with noise. The original amp used a digital signal and the amplifier was muted during silence. There was virtually no noise. The problem with using the P.C. power supply is that it brings the noise right into your circuit. There are differences in the grounds which cause problems similar to ground loops. Your solution appears to use ferrites, but there is an active solution as well. Check out the BA3121 ground isolation chip. I was headed down that path, but the cost and part count was getting ridiculous. Using the external power supply that we use, brings in clean isolated power so I don't have to try to filter the noise out.

applejuice
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Re: My Nucore Installation - Ground Loop Noise Solution

Post by applejuice » Sat Apr 03, 2010 12:34 pm

Thanks for the info on the chip, sound interesting. I've been trying to install everything into an existing case (see my other post) so i can plug it into any stock rfm to instantly upgrade it. I wish i could fit 2 psus in there, or find a better small form factor psu with isolated grounds or something. I was pretty sceptical about this ferrite ring type solution, but seems to work pretty well.

I found it here

http://www.maplin.co.uk/Search.aspx?cri ... &source=15

and there was another option that i may try out, which looks to be an active design. You can find this type of thing cheaper on ebay etc

http://cgi.ebay.co.uk/ws/eBayISAPI.dll? ... 0102477564

as maplins isn't renowned over here in the uk for competitive prices, but it is handy for those 'i want it now' moments :)


Is there any way to utilise the amp chips mute signal directly from nucore? Seems a shame to have that functionality and not utilise it.
Jim

http://tournament.mypinballs.com

"All parts should go together without forcing. Remember the parts you are reassembling were disassembled by you. If you can’t get them together again, there must be a reason. Do not use a hammer." ~ IBM

Menace
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Re: My Nucore Installation - Ground Loop Noise Solution

Post by Menace » Wed Jun 02, 2010 11:47 am

I've ordered a ground loop iso as well in hopes that I can get away with a single PSU as well. I'll post my results once it arrives.

Doug

luvcraft
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Re: My Nucore Installation - Ground Loop Noise Solution

Post by luvcraft » Thu Jun 03, 2010 5:21 pm

Nice! I was going to try a ferrite bead myself when I got to this point in the installation before trying a separate power supply, and I'm happy to see that it works! :)

Menace
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Re: My Nucore Installation - Ground Loop Noise Solution

Post by Menace » Thu Jun 17, 2010 11:41 am

Menace wrote:I've ordered a ground loop iso as well in hopes that I can get away with a single PSU as well. I'll post my results once it arrives.

Doug

Just thought I'd report back with an update. Received the ground loop iso that I bought off Ebay for $1 (Plus $8 shipping), installed it last night and I now have nice clean sound from the OEM amp running off the mobo power supply.

Doug

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