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Old 9th November 2012, 05:25 PM   #291
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Well, I don“t believe that the problem be the capacitors... I used a pair of Nichicon electrolytic capacitors on serķe and the result is the same.
Click the image to open in full size.


The offset on this ampli is a "russian-mountain"

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Old 10th November 2012, 01:31 PM   #292
oz7aff is offline oz7aff  Denmark
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Quote:
Originally Posted by blackdod View Post
The offset on this ampli is a "russian-mountain"
I don't know the meaning of "russian-mountain".

But I know that if you'r setup is like this:
Click the image to open in full size.

There shall be no DC offset to measure with the VDC meter.
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Old 10th November 2012, 07:04 PM   #293
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Thanks for your answer.

Yes, is my setup, but I never take the DC values with the headphones connecting.

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PD: "russian-mountain"; when something mimics the movement of a roller coaster.
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Old 10th November 2012, 07:47 PM   #294
oz7aff is offline oz7aff  Denmark
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Then you can't use the measurement, try to connect a 1 kOhm resistor as a dummyload.
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Old 10th November 2012, 08:08 PM   #295
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Quote:
Originally Posted by oz7aff View Post
... try to connect a 1 kOhm resistor as a dummyload.
Thanks Max, I“ll try.

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Old 12th November 2012, 07:43 AM   #296
bismuth is offline bismuth  France
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Quote:
Originally Posted by blackdod View Post
Thanks Max

Well, the offset is around 140 mVolt when the my amp is warm (with the Non Polar Cap) and I don“t like this. IMHO, 140 mVolt is very dangerous for a headphone. I supposed that with this Cap, the offset would have be around 0 mVolt.
There is maybe something wrong elsewhere with your board, mine is barely around +-25mV Offset at startup, and it goes down to around +-3mv after around 10 minutes when warm, and I have NO capacitor on output, only 2,2uF on input.
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Old 12th November 2012, 07:28 PM   #297
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Thanks guys

If I conecct a resistor on the output, the offset is 0 mvolt, but I think that my board have any problem because when I start it up (with out dummy load) the offset goes down to 200 mVolt to around 0 mVolt and when it warns up goes to 140 mvolt

I will check the rest of the board.

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Old 12th November 2012, 07:56 PM   #298
oz7aff is offline oz7aff  Denmark
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As I said before, the measurements without the resistor is of no value, measuring on a capacitor without connection on both side is a waist of time.
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Old 12th November 2012, 08:21 PM   #299
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Originally Posted by oz7aff View Post
As I said before, the measurements without the resistor is of no value, measuring on a capacitor without connection on both side is a waist of time.
Thanks Max. Do you think the amp It“s ok?

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Old 12th November 2012, 08:24 PM   #300
oz7aff is offline oz7aff  Denmark
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If there is no Offset voltage with the 1 kOhm Dummy load, then I am shure that the amplifier is working OK.
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