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Old 9th May 2006, 06:59 AM   #21
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loic,
I copied my reasoning from another thread re. the DC offset.
Out to ground is not that critical. Anything between -1 and +1V is fine. DC between OUT- and OUT+ is what the speakers see so try to match for less then 100mV to start with. Less is better.

Looks like you have about 4mV (0.022 - 0.018) between outputs.
This is perfect.

The AC voltages can only be measured when a signal is applied to the input. You will need a steady sinewave. Either comming from a generator or you could burn something on CD. There is a current thread about generating sine waves here.

/Hugo
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Old 9th May 2006, 08:46 PM   #22
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hugo

Do i need an input cap anyway or not?

I burnt one CD with 60 hz sinewave and played it on my CD player linked to the amp and speakers connected.

I can hear the signal but still measure 0 Vac across R42/43 and R5 for example...

What is the problem? or what does it means ?

My multimeter is set on Vac measure

Loic
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Old 9th May 2006, 08:55 PM   #23
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Loic,
I can't say you need it, as your DC is nicely low and the purpose of the cap is only to prevent incoming DC be presented at the output. If it makes you feel better, add it. At the expense of a small tradeoff in sound.

The AC that can't be measured is a mystery to me at the moment.
Can you measure it across R6?

/Hugo
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Old 5th June 2006, 09:01 PM   #24
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Default aleph x debuging

I finally borrowed an oscillo to a colleague.

I found the problem with ac level. I was using the variable output of my cd player to the lowest output level meaning lowest AC voltage across resistors.

I then increased output level of my cd player output. I was then able to mesure AC voltage across resistors !!!!

thnks for your help.

loic
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Old 5th June 2006, 09:08 PM   #25
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Nice, enjoy the music before you start fine tuning.

/Hugo
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