Some people have mentioned that they found cameras where they could
disable the automatic gain control (AGC), but still found the quality
of the built-in microphone to be poor.  One solution for this is to
use an accessory mic from a pro audio manufacturer that is designed
to be compatible with camcorders.  The Sennheiser MKE 400 is a highly
directional shotgun mic for this purpose if you don't require the
recording to be in stereo.

Dave Theis