The output is distorted before it reaches the saturation voltage.

[Erickuo]

In the saturation concept of OPA, if the output does not reach +-VCC, the Vout of OPA will not be distorted.
But I don’t understand why it is distorted when I input a +-1V sin wave at the Vin ,(I zoomed in 17 times, so Vin can normally input +-1.4V sin wave).
Below is my circuit and waveform.

 

[HAYK]

Do it my way and you will be happy.

You can power with +/-40V and get 70W.

 

[phase_accurate]

Use a current source instead of R4. Or split R4 and use an old-fashioned bootstrap circuit.

Regards

Charles

 

[Mooly]

But I don’t understand why it is distorted when I input a +-1V sin wave at the Vin ,(I zoomed in 17 times, so Vin can normally input +-1.4V sin wave).

Your upper TIP41 has insufficient base current available. As the output swings higher toward Vcc the voltage across the 500 ohm reduces even more leaving no base current being available. At 15 volts peak output voltage you have leaves just 9 volts across the 500 ohm which is just 18 milliamps. In reality you need a few hundred milliamps base drive current to be available.

 

[jan.didden]

What is the idea behing an output stage behind the LM3886?
Most probably the result will be worse than without the extra stage.
Am I missing something?

Jan

 

[OldDIY]

The diagram is incorrect.