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Old 13th May 2010, 11:49 PM   #11
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I get a lot of noise if I touch the inputs on the JFET's.
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Old 14th May 2010, 12:53 AM   #12
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If I so much as plug in the power cord with the amp on I get noise. I got no idea why. That is with the power off.

I have no idea what is wrong, I give up. I am just going to have to wait who knows how much time and get a PASS B1 I guess.
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Old 14th May 2010, 08:39 AM   #13
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the lm317 is only for the positive supply.

the output will be xx volt/0 volt or GND.
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Old 14th May 2010, 10:42 AM   #14
Joris is offline Joris  Netherlands
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robertor, I disagree with you, it IS possible to create a positive and a negative voltage with 2 pieces of LM317. It would be nicer to use LM337 instead, but it should work without trouble.
I think since it is a shared power supply for both channels, the problem isn't in the power supply, it must be in that left channel. You should check the circuit board for bad ground connections.
You could also try to swap the amp inputs, so left channel becomes the right and the right becomes the left, this eliminates any doubts about the amp itself.

Could you post me a picture? So I have a clue what we're talking about exactly..

Best regards
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Old 14th May 2010, 10:45 AM   #15
Joris is offline Joris  Netherlands
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Quote:
Originally Posted by Destroyer OS. View Post
If I so much as plug in the power cord with the amp on I get noise. I got no idea why. That is with the power off.

I have no idea what is wrong, I give up. I am just going to have to wait who knows how much time and get a PASS B1 I guess.
If I understand it correctly, you get noise when you plug in the power cord of the amp that is connected to your circuit? If that's true, you certainly have a ground loop.
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Old 14th May 2010, 03:00 PM   #16
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Yeah well I put the whole thing into the closet until I need the box again... I can not even imagine how a ground loop was being created without the circuit even on.
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Old 14th May 2010, 07:27 PM   #17
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re-build the power supply with 317/337 and try another time.

don't work fine?

search for another problem.

must to go for exclusion: that work fine and the problem persist? check the fet or buy some j-fet buffer PCB come from china.

jims-audio have the borbely.


p.s.: i'm not able to build a power supply work fine then i buy from some Chinese ebay seller. the price is absolutely absurd and make their work.
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Last edited by robertor; 14th May 2010 at 07:31 PM.
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