biasing of push and pull output amplifier

[fvm]

hey guys
i need help to in designing the output stage of audio amplifer
the class ab,im having problem in biasing the circuit
any ideas??

 

[audioguru]

There are thousands of audio amplifier circuits on the internet that use class-AB biased complementary output transistors.
Some use diodes and others use an adjustable Vbe multiplier transistor for the biasing.
The diodes and transistor automatically adjust the bias current in the output transistors when changes in temperature try to change the current.

 

[fvm]

actually im interested in using vbe multiper but unable to adjust the voltage across vbe multipler??????

 

[Nigel Goodwin]

actually im interested in using vbe multiper but unable to adjust the voltage across vbe multipler??????

The right hand one of those two circits is a Vbe multiplier make the top resistor feeding it's base variable to adjust the bias.

 

[bountyhunter]

hey guys
i need help to in designing the output stage of audio amplifer
the class ab,im having problem in biasing the circuit
any ideas??

Here's a working design for driving headphones that illustrates a classic design technique including temperature compensation.