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Old 15th June 2010, 11:59 AM   #1
Skorpio is offline Skorpio  Denmark
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Join Date: Mar 2004
Location: Denmark
Default F4 sweet spot...

I had read this nice article:

It looks like replacing the two 10R resistors at the source of the input follower will enable you to reduce distorstion by 80%?

Is this usable for a DIYer without a distorsion analyser? I guess the sweetspot will not be the same point as minimum DC-offset?'

But you might have a option to try to listen to different settings of the pot....

Will 20R trimmer be a good starting point or perhaps 100R?
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Old 16th June 2010, 12:32 AM   #2
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No, but you can trim the distortion a bit by replacing the
two resistors with a 20 ohm (or so) trim pot.

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Old 17th June 2010, 06:16 AM   #3
Skorpio is offline Skorpio  Denmark
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Join Date: Mar 2004
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Ok, I should try...

The same might apply to the F4 output stage? The zero off-set level might not be the most optimal setting regarding distorsion?
I have build the F4 with single 50V supply, so could it be possible to tweek on the output also?
This might be 0.47 to 0.1 Ohm source resistors?
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Old 17th June 2010, 08:31 PM   #4
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It's possible to tweak, but don't expect a lot of improvement.

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