Audio Amplifier cuircit by LM386 and LM358

[goldsmith]

Dear Friend
Hi
is your mean that my simulation is not correct????!!!!!!!!!!!!!!!!!!!!!!!
i said to you that now i have this circuit in my home. and its work is good. is your mean my oscilloscope cant show actual waveforms?????!!!!
my speaker ( of my computer ) is home made. i designed it. for pre amplifier i used one LM358 Ic as buffer and negative gain amplifier. and my end amplification is with a simple complementary amplifier.

---------- Post added at 23:07 ---------- Previous post was at 23:04 ----------

What is your mean with distortion?
Current distortion?
Voltage distortion?
Phase distortion?
Frequency distortion?

 

[FvM]

I'm talking about Crossover distortions

I added the voltage drops similar to that generated by the LM358 output transistors and a 50 µA current source and get the below waveforms:


According to my experience, the real LM358 circuit behaves almost identical.

 

[mycolee]

pay more attention to self excitation

 

[goldsmith]

Dear FvM
Hi
Your simulation is with lm324(with your title) But you said Lm358!!!!
See these pictures , please:

I cant see cross over distortion here. please use this circuit ( my first attachment) and give me its result . i said to you that its result is very good . believe me my friend.
Kind Regards
Goldsmith

 

[FvM]

- LM358 and LM324 are identical OPs, only difference is 2 versus 4 amps per package
- setting the frequency to 1 kHz and input level to 2V matters. Cross-over distortions are much smaller , but still perceptible

There's a certain difference between the PSPICE and LTSPICE result using your input signal settings. I guess, PSPICE is using a larger timestep. You possibly need to reduce it in the PSPICE analysis parameters to get an acurate waveform.

 

[goldsmith]

Dear FvM
Hi
You're Right


But see these pictures please:

. Distortion is 50mv. And i did this circuit with 741 opamp and again distortion was 50mv . do you think that 50mv is important? because i can not sense it in out put voice of my speaker. I think these Ic s not biased as class B. but not biased as well as. But it is at class ab ( approximately)
Thank you for your attention
Best regards
Goldsmith

 

[FvM]

because i can not sense it in out put voice of my speaker.

This may be either a problem of speaker quality or your skills in percepting distortions. If you ask a sound engineer, he will hear it.

There's apparently a misunderstanding about the purpose of diodes in the simulation circuit. I implemented them to simulate the real behaviour of the LM358/LM324 output stage, that isn't correctly represented in the National Semiconductor (neither other manufacturers) SPICE model. With the diodes, you get class B behaviour, which is also present in the real LM358/LM324.

When you add a complementary output driver without additional bias voltage generator (just connecting both base terminals to the OP output), you get a similar behaviour, even with a class AB OP, e.g. LM741.

Finally, if we take a look at your original 3 OP amplifier, we can expect, that the worst distortions will occur at a stage, that is driven to a medium level of e.g. 100 mV. Because each stage has a different level, there's a good chance to meet this condition at least for one stage. In so far, it's reasonable to make the simulation with medium level, as I did. Then the cross-over distortions can hardly be missed in the simulation result and will be also perceptible, I fear.

 

[goldsmith]

Dear FvM
Thank you for your guide
Goldsmith

 

[mf1364]

Hi every body
eventually , I achieve my intercom circuit , in the next step I want to remove the connecting wires between two intercom circuit and transmit/receive sound wireless so do you any module or IC that can help me , what' your idea about simcom ICs ?