Noisy LM386 based audio amplifier

Inspired by this post from Salvage, I ordered a couple of gameDR Smack Talk for the XBOX units. The volume is way too low to drive a speaker directly, so I need an audio amplifier.

That led me to this post from Calculon320 on building an amplifier with an LM386. I breadboarded the audio amp, and it definitely amplified. However it also added a lot of noise. It could be cleaning it all up on a perf board would fix some of that, but it is very noticable.

I tried a few variations (20, 50, and 200 gain, with and without bass boost) from the applications examples on the LM386 datasheet. Essentially the same results. A bit less noise with less gain, but that is to be expected. Maybe it is not so much noise as distortion.

So, anyone have any thoughts on cleaning up the signal?

Oh, I just had another thought. I'm driving the output from the Smack Talk's headphone jack. There's another connector that's designed to connect to the XBOX 360 controller. That might be more like a line out. Perhaps I'd have better luck amplifying that cleanly.



I also have to deal with an
I also have to deal with an audio amplifier in my project. I do not have the definitive solution to take out the noise but my suggestion is to place noise suppression caps (0.1 microF) near every IC (between the V+ and GND pins) and maybe use shielded cables in case you have placed the speaker far away from the rest of the circuit.

Calculon did just that and it works like a charm.

remember to keep the
remember to keep the capacitor’s legs as short as possible, that also helps.

Cool. I’ll try that
Cool. I’ll try that tomorrow. Thanks!

The LM386 oscillates very easily. To prevent this, put a .001ufd cap between the input pin and ground as close to the IC as possible. This solves the stability problem 99% of the time.

Mystery Solved

Apparently the issue was the total crap speaker I was using. It was from a really cheap pair of headphones. Once I replaced it with a slightly better speaker, the sound quality was MUCH better.

Thanks for all the help!