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Old 10th October 2012, 08:51 PM   #51
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Originally Posted by Marc Vi. View Post
Why not use the way I proposed? Marc.
With the LM3886, your solution is probably better.
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Old 10th October 2012, 10:10 PM   #52
Marc Vi is offline Marc Vi  Netherlands
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Adjusting the supply voltage on one side in order to trim out the offset voltage is a bad solution for every amplifier.

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Old 11th October 2012, 08:55 AM   #53
AndrewT is offline AndrewT  Scotland
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The output offset should be substantially independent of the supply rail voltages in any opamp style amplifier.

However, a VAS stage without CCS supply/source will change it's Iq when supply voltage changes (both rails changing together), and this changed Iq with push/pull more or less current through the Collector load of the input transistor. This changed collector current will change the offset. This is one of the big disadvantages of a bootstrap feed to the VAS in a P3A (ESP) amplifier.
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Old 23rd March 2014, 07:23 AM   #54
0x4452 is offline 0x4452  United States
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Marc, I successfully applied your tip in my DIY studio monitor (with LM4766 - another BJT chipamp).

Previously, due to the low feedback resistance (200R and 3k3) in my design, I needed a large feedback capacitor. There was a slight but audible distortion, which is now gone or at least below my threshold .

Schematic here: http://rdimitrov.info/blog/show.php?entry=Minimalistic%20HIFI%20Bi-Amplified%20Speaker%20System

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Old 23rd March 2014, 01:52 PM   #55
mlloyd1 is offline mlloyd1  United States
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thanks for the link. i found a new band i like - Pink Tomato.

any recommendations?

sorry for being off-topic ...
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