ruby amp buzzing

[dmm128]

So I just finished building a ruby amp. It sounds fine until I crank up the volume and gain. When I do that I get a sustained buzzing sound. Is this a pot issue or something else? Here is the sound that I am getting.

http://www.youtube.com/watch?v=Q52_rIeipl0

[Top Top]

Hmmm... it is self-oscillating... That is a fairly common problem with Ruby builds.

You probably have a bridged trace somewhere. I had the same thing, but now I can't remember what trace was bridged. I think on mine it was something in the area of pins 1&2 of the 386 chip, or the resistors connected to the transistor.

[dmm128]

Is there any other things that can cause this?  I scraped off anything between the ic pins and any other close joints and same result.

[Quackzed]

the ruby i built does this as well, when the battery starts to die, beyond a certain point on the volume it just puts out a farty sound.
if i dont replace the battery i have to keep turning the volume lower and lower to avoid this, untill i change the battery
.     the ruby and other 386 circuits are battery hogs and i usually only get 2 or 3 hours if i have it cranked.
try a new battery!

[dmm128]

Thats it!!!  The battery I was using was about 6.5v and switched it out with an 8.9v and problem solved!  Also during my debugging I checked out the datasheet and saw that in one of their examples they grounded pin 2 and had pin 3 going to the pot.  That arrangement worked at full volume with the 6.5v battery.  Thanks!!!