I know this may sound like a "why the heck would you do that?" kind of question, but I just finished my BMP and its really lacking in volume. I used some old electrolytics that I had, but I doubt that that is the problem...any ideas?
And yes, its a new battery.
IIRC the bases were louder with the source connected to them than the collectors...trace through the ckt and see if you can tell where amplifying is taking place [using a probe or injecting a source]
A base that's louder than a collector to a given source input whle in powered circuit indicates amplification...I believe all 4 transistors are intended as amplification units in the BMP. An emitter follower would usually not amplify, or very little.
Taking transistor voltages of Emitter base collector of each transistor from ground is often a quick route to identifying bug.