LM380 guitar amp has a pulsating sound at high volume level only, how can I fix?

[PRR]

> PRR, let me know if you think I should still add that 10uf cap?

Why isn't it there already ? ? ?

Look around at other half-supply dividers. 99% of them have a cap bypass.

And you could just try it quicker than I can type this....

[Jasonmatthew911]

> PRR, let me know if you think I should still add that 10uf cap?

Why isn't it there already ? ? ?

Look around at other half-supply dividers. 99% of them have a cap bypass.

And you could just try it quicker than I can type this....

Will do....By the way I did notice that I'm now getting a very low volume stat-icy sound in the signal background...Any idea how to get rid of it?...Maybe the 10uf cap could help that....At least motorboating is gone....Do you think adding the 4K7 resistor from pin 2 of LM384 to GND helped, or do you think it was the changing of the 2,200uf output cap to 560uf or both?...That's the 3 things I did that got rid of motorboating, changed big cap at output, added the resistor, and changed the LM380 for an LM384....I guess since I have to do the same to the second circuit I made, I will try 1 change at a time, to see which part(s) made the difference...

[Jasonmatthew911]

So, motorboating is gone, but there is now a low volume static radioish sound riding in the background of my signal....My signal is a lot clearer now, except for there is a little low static noise dirtying the signal, (It's kind of like a loud turned ON sound, with low volume static noise...Also sounds like dirty contacts, but isn't)...It's no big deal with the overdrive, but seems a little too noticeable with the clean sound...As soon as I turn the Volume up just a little bit, the low static sound is present, it goes up a little in volume till about half way, and then the low static noise stays the same volume from half way to full volume...What could it be or what could I maybe do to get rid of it???...If I can get rid of that, the amp will be working perfectly.

[Jasonmatthew911]

Actually Blackcorvo you were right, it was the resistor from pin 2 of LM380 to GND that stopped the motorboating...I even changed it to a 10K and it did the job as well...I also went ahead and added the 10uf cap PRR said, and lowered my output caps to 470uf...

Ok, since I did 2 of these circuits...I now have one working perfectly well with an LM380 power stage, sounds good and clean signal as it should be, even with the volume all the way up, it is pretty quite, and then I have the other circuit which is the one giving low static noise in the signal background...The only difference of the 2 is that this one has an LM384 power stage, which is almost the same thing, just gives more power at higher Voltage...Could it be the LM384 or something else?...I already put both circuits in their enclosures, but I guess I can still take this one apart to audio probe where the static noise is starting in the signal path, if that's what it is...Anyone know where that little static noise is generated?