>I rewired my phone jack so that the headphones would be in
>than parallel as suggested in "QRP Power", page 3-22. The Op amp seems
>to drive my phones louder before clipping. Has anyone else tried this.
>Really seems to work for me. I gotta wonder why it wasn't designed this
>way, is there a draw back that I'm not aware of?
I agree, that's the way to wire headphones, especially when driven
from a feeble driver like an op-amp.
But there IS a catch...
You must be careful not to ground the headphone jack. The shell
of the jack is the common-point between the two headphone elements.
When you wire each element is series, then one "hot" element-end
ends up going to the ground-plane on the printed circuit board.
The headphone jack shell is now at a half-voltage point.
If you try to wire the jack in a series-connected way, and find
you only get audio out of one side of your phones, the cause could
be a grounded shell. Insulating the jack from ground should solve
the problem. Or using a plastic (insulating) case to mount
everything solves the problem too.