New Amplifier 95% done-what do you think?

[zox2003]

To Thanh

TO THANH:What do you mean when you say that your amp works but not good.Explain please...

Zox

 

[Upupa Epops]

To Thanh : I don't know, if is it good news, try to simulate or listen .

 

[hienrich]

thanh: do you men 1 ohm res on the voltage amp transistor's emmiter

I guess these is just small enough change it to zox's value which is

33 ohm . dont forget about the emmiter internal resistance (re)

33 ohm is a good value to compensate with this one.

expect sonic changes when you try to change resistor values.

try 68ohm, 56ohm, 47ohm, down to any value available.

regards,

hienrich

 

[zox2003]

any more comments

Any more comment or sugestions?

 

[MikeB]

Hi !

Your amplifier looked nearly finished, have you tried different
inputtransistors ? I think mpsa56/06 might not be best choice,
they are a bit slow...

Mike

 

[zox2003]

Input transistors

Would 2N3906 be better choice?What is wrong with MPS56.

Thanks.

 

[MikeB]

I don't know 2n3906, would have to take a look...
mpsa56 has low transconductance, high outputcapacitance,
this results in low gain/bandwidth.
2n5401 seems to have nearly 3 times the gain/bandwidth.

Mike

 

[Marc Vi]

Place a capacitor of 100 nF over the bias circuit. Make the output circuit a EF II type as suggested by Self.

Marc.

 

[Marc Vi]

I think, but I'am not quite sure, that it is better to give the emittor resistors of the TIP 31C and the TIP 32C the same value because otherwise you get a great DC offset voltage which has to be regulated down by the feedback.

Marc

 

[Marc Vi]

The resistor of 1 k between the collector and the variable resistor of the bias circuit is to small to give the output stage sufficient idle current. Make it 4k7.

Marc.