You might add the 10Ufd to the bias pin.
You could also try a little antenna in the mic input to see if it makes it worse - 5-6" of wire would do for a test.

 

Tried both of those, neither seems to make a difference.

I just don't understand why the output of the mic acts like it is so poor. It shouldn't have to be even a good quality mic and pre amp to reproduce a decent enough signal for the lights. Not nearly as good a quality that would be needed for actual audio applications.

Looking at them both on the scope using a test tone, there seems to be hardly any difference between the signals.

 

Here is a pic of the waveform for the the mic input. The amplitude is usually higher when I am playing the lights, and at higher amplitudes the waves doesn't change in any way except the height. It looks almost identical to the line in waveform just a tiny bit thicker.

 

It may or may not have to do with your problem, but thicker = instability. There's a high-frequency component riding on your waveform.

 

It may or may not have to do with your problem, but thicker = instability. There's a high-frequency component riding on your waveform.

I see....any tips on how to get rid of that?

 

100pF to ground after that 47k resistor should do it! Or, since the source is probably the op amp gain stage, put .0068uF or so in parallel with the 200kohm feedback resistor.

 

100pF to ground after that 47k resistor should do it! Or, since the source is probably the op amp gain stage, put .0068uF or so in parallel with the 200kohm feedback resistor.

The .0068uF again improved, but didn't totally fix the issue. I think I am at the point where the response is good enough, I can probably sleep at night if I leave it the way it is. Of course I would always be open to further comment or suggestion

Thanks everyone for all the help it is much appreciated!

 

Hello,

Is the universal powersupply you are using a regulated one?
If not, put it to 15 Volts and use a 7812 to power the opamp and mic.

Bertus

 

Hello,

Is the universal powersupply you are using a regulated one?
If not, put it to 15 Volts and use a 7812 to power the opamp and mic.

Bertus

It is regulated

 

Hello,

Can you measure the 12 Volts on the scope?
That way you can see if it is clean.

Bertus

 

Hello,

Can you measure the 12 Volts on the scope?
That way you can see if it is clean.

Bertus

Scope shows perfect 12.0V

 

Hello,

What do you see on the scope, when you set it to AC and scale the sensitivity to the mV range?

Bertus

 

Hello,

What do you see on the scope, when you set it to AC and scale the sensitivity to the mV range?

Bertus

Here is a pic at 5mv

 

Hello,

I also asked if you had decoupling capacitors on the 7805.
If not, the regulator may oscillator.

You can also put a resistor of 10 to 100 Ohms between the +12 Volts and the opamp.
This will "isolate" the opamp from the powersupply.

Bertus

 

I added bypass caps, and nothing was changed. I can try the isolating resistor tonight.

 

It might be worth scoping pins 3 and 4 after a clap to see how long the pulse decay is.

 

I think the decay is significant. You can see it in the lights when I clap my hand. I would say the high frequencies linger for almost half a second.

 

Hello,

The decay of the leds is set INSIDE the BA3830.

The peak input voltage will determine the time the leds will stay on.

Bertus

 

So if I match the peak output V of the mic to the Peak output of the line in, the delay should be the same? Unless there is a delay of some sort inside the mic circuit that sends the signal to the BA3830 for a longer period of time.

 

Hello,

Yes, You can have a look at the signal using the line input
and compare it with the signal coming from the mic input.

The mic input can also pickup noise from the surroundings.

Bertus