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Old 17th June 2012, 04:17 AM   #1
ljm_ljm is offline ljm_ljm  China
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Default HA-PRO2

After a few test and fixed.

Now the HA-PRO2 monitoring design with headphone amplifiers sample

VER1.
VER2.
VER3
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Old 17th June 2012, 08:26 AM   #2
Nisbeth is offline Nisbeth  Denmark
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I know we're not going to get it but I am still going to ask: Schematic?

/U.
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Old 18th June 2012, 07:56 AM   #3
ljm_ljm is offline ljm_ljm  China
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The main structure as shown in figure
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Old 7th November 2012, 05:40 PM   #4
geladk is offline geladk  Denmark
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Is it possible to buy PCBs without components for this amp anywhere?
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Old 24th May 2013, 02:01 AM   #5
ljm_ljm is offline ljm_ljm  China
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Quote:
Originally Posted by geladk View Post
Is it possible to buy PCBs without components for this amp anywhere?
I do not know to have
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Old 30th May 2013, 01:09 PM   #6
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I have just built one of these headphone amps, works OK but some mains hum at high volume settings but this doesn't intrude at normal listening levels.

Click the image to open in full size.

Click the image to open in full size.
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Old 30th May 2013, 10:33 PM   #7
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You built the amp as a Class I (earthed) device. You may have some ground loops over the case in there. I would assume the PCB design did not take this into account.

And the obvious one, you didn't use shielded cables for the input.

(Temporarily take the board out and put in on a piece of cardboard or whatever to test #1.)
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Old 31st May 2013, 12:49 PM   #8
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Quote:
Originally Posted by sgrossklass View Post
You built the amp as a Class I (earthed) device. You may have some ground loops over the case in there. I would assume the PCB design did not take this into account.

And the obvious one, you didn't use shielded cables for the input.

(Temporarily take the board out and put in on a piece of cardboard or whatever to test #1.)
Thanks for the tips It was the earth, now totally silent even with unscreened cable on the input
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Old 16th August 2013, 03:11 PM   #9
ljm_ljm is offline ljm_ljm  China
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Originally Posted by activexp View Post
Thanks for the tips It was the earth, now totally silent even with unscreened cable on the input

Does not need to be connected to earth, yellow green wire.

Only need to connect the power. Disconnect the line.

PCB through the screw and wire.

Normal HA-PRO connection. Signal to noise ratio is very good.
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Old 16th August 2013, 04:25 PM   #10
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Quote:
Originally Posted by ljm_ljm View Post
Does not need to be connected to earth, yellow green wire.

Only need to connect the power. Disconnect the line.

PCB through the screw and wire.

Normal HA-PRO connection. Signal to noise ratio is very good.
Yes, it's totally silent now
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