[cazoo]

so i'm having problems with my pimeta. it was an easy build and everything was fine but when i tested it out, a loud shrieking air raid siren sound came out of the headphones.

i'm backtracking my steps to see what i did wrong but maybe the air raid siren sound is a dead giveaway to something?

your comments are always helpful, thanks.

 

[Nisbeth]

I seem to recall getting horrible howling noises by using a pimeta as a preamp, which shorts out the ground channel. Check your ground connections to input/outputs (especially if you've cased the board) Otherwise check for incorrectly placed components, opamps/buffers which are the wrong way around, and of course solder bridges on the underside of the board

/U.

 

[tangent]

Basic Troubleshooting for Headphone Amplifiers

 

[sbelyo]

I would say, maybe a short somewhere.

The input and output ground are not the same. If you are using a metal case and uninsulated jacks, then they are shorting together.

Try the amp outside of a case without touching any metal and see what happens.