No, it's not a bad B-movie--it's what happens to most directional microphones when you move them close to the sound source. When you do, there's a bass build-up. And to prove it I have some examples. You can think of it a bit like a low frequency tone control; move the mic in--the sound gets more "bassy", move the mic out; the bass rolls off.
This can be good (i.e. when a good singer moves in on the mic for an intimate vocal part) or can be bad (i.e. "why does my (insert whatever sound your trying to record here) sound so bass heavy?").
Here an example of me playing with the proximity effect on a AKG 414 set on a cardioid pattern. I start out as close to the mic as I can get and then move out an inch at a time.
In this example there is no proximity effect to speak of. Something to keep in mind with using one of these.
This page written and maintained by: Phil Calvert