LM3886 without electrolytic feedback capacitor and (hardly) no DC offset voltage

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Hi Marc, this is more about learning to control - adjust offset (as with your case).

This is my original schematic.
I have remove Cin, Ci & Cc
Rin =10K
Rb=330 R
 

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Hallo Zakman35,

Don't remove Ci because the input resistance will be dependent on the output resistance of the pre-amplifier and that may change the output offset voltage of the LM3886 quite a lot.

And, if there is an output offset voltage on the pre-amplifier, that output offset voltage will be multiplied by 33 !!

Don't remove Cc because it prevents noise and - if necessarely - oscillation.

Marc.
 
Don't remove Ci because the input resistance will be dependent on the output resistance of the pre-amplifier and that may change the output offset voltage of the LM3886 quite a lot.

And, if there is an output offset voltage on the pre-amplifier, that output offset voltage will be multiplied by 33 !!

Don't remove Cc because it prevents noise and - if necessarely - oscillation.

I install Ci back again (no changes at offset).
My pre amp (minidsp) is AC coupled at the output, so no dc from there.

I will try tomorrow to install back the Cc cap and report back.
 
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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