HOW TO increase the class-d's gain?

[aobuke]

HOW TO increase the class-d's gain?
i use the multisim make a class-d amplifier,
but the result is worse,when 8KHz(-1v~1v) sin is in,the output
is only -1.6v~1.6v,how to increase it ?

 

[Saturnus]

Increase R4

 

[aobuke]

Increase R4£¿

but i think the R4 is the integral resistance,I think it doesn't matter with the CLASS-D'gain.

 

[Saturnus]

Could be wrong but to me it looks like the feedback resistor.

Since the gain is set by the relationship between the input resistor and the feedback resistor. Either increase the feedback resistor or decrease the input resistor.