Audio Amplifier Design

[Samson Jabu Masemola]

Hi everyone

I would like to ask some help on an Audio amplifier. My load is 8Ohm. and to my calculations using TIP31C/TIP32 and with each having a VCE(SAT)=1.8V I got to my output power being Pout approaximately 8W (5.65W RMS). I managed to simulate the circuit atached and alreadty I burned R7. Help with what is the wrong this I am doing.



Regards
Samson

 

[Arouse1973]

What wattage resistor is R7? You also need some bias for your VA stage.
Thanks
Adam

 

[Samson Jabu Masemola]

What wattage resistor is R7? You also need some bias for your VA stage.
Thanks
Adam

Thanks.
For R7 I used 0.25W, But thanks I noticed that the current that was flowing through this resitor is too much. By VA you mean the amplifiying stage?

 

[Arouse1973]

Thanks.
For R7 I used 0.25W, But thanks I noticed that the current that was flowing through this resitor is too much. By VA you mean the amplifiying stage?

Yes voltage amplification stage.

 

[Samson Jabu Masemola]

Thanks. Now if I want to put a volume control circuit and achieve the 300-3400Hz frequency sweep. Can you please advice me on that.

 

[Arouse1973]

Thanks. Now if I want to put a volume control circuit and achieve the 300-3400Hz frequency sweep. Can you please advice me on that.

You can't change the frequency buy adjusting the volume.
Adam

 

[Samson Jabu Masemola]

You can't change the frequency buy adjusting the volume.
Adam

Thanks. I am aware of that. I know I have to use capacitors (I.e. coupling, bypasss and decoupling) to determine the frequency sweep. What I'm asking is the Volume control, where to put it in my circuit and how to configure it.

I have attached my latest circuit using Diff Amp and power stages, I tested it using 2N2905/2N3085 and only the NPN transitor draws about 350mA while the PNP draws 30mA. And my output signal is oscillating around 0.7Vdc. Do you know what could be the issue here?

 

[Arouse1973]

Here is a simple amplifier circuit. The input is 200 mV sine wave @ 1KHz. The output is approx. 10 V Pk-Pk into an 8 Ohm load. See if you can see what might be wrong with yours. This amplifier is not ideal but I have tried to keep it as close to what you have done.
Adam