[flatst]

I posted this in the Help forum and was told that this would be a better place for it.
 
I just built my O2 amp and there seems to be a buzzing sound in my right ear of my Mad Dog. Currently, my setup is computer>O2>Mad Dog. The buzzing only starts about 30 seconds after I turn the amp on and doesn't change if I change the volume. I'm currently running on a 15VAC 500mA AC Adapter.
 
Any suggestions?

 

[NA Blur]

Sounds like a ground loop or bad capacitor.  Double check that caps are in their correct locations and then try working out the ground loop.

 

[flatst]

After doing further testing, I found that, when I was checking the output for DC by measuring from pin 1 of P2 to the other terminals of P2, the bottom two pins were -3.6 and -40 mV respectively. They should be as close to 0 mV as possible.
 
Does anyone know what causes this?

 

[patchoncas]

DO NOT plug your headphones into that amplifier, you might destroy them with that DC offset.
 
Seems like a problem with the feedback loop part of the amplifier. Check the opamps and surrounding components.