As crazy as it might sound, it is not an uncommon practice. This is also called the “Pressure Zone Microphone” or “Boundary” mic. There are basically 2 schools on having a mic on the floor:
- Having a condenser microphone as close as possible to the floor (some use a credit card to check how close to the floor it is), a few feet directly in front of the bass drum.
- Having a dynamic mic, laying on the floor, a couple of feet directly in front of the bass drum.
You might believe that being so low (or on the floor) it picks up the low end. You’d be mistaken. It actually picks up a mid to high end, sometimes with a “roomy” vibe—depending on the room and its surfaces.
It adds a lot of character to the final mix, a sort of “edge”, but with a lot of punch. An effect that would be difficult to replicate in other ways.
As you can see in the image above, in that particular session, the engineer laid down a floor tom between the floor mic and the bass drum, so the microphone (a Shure SM58) is not only picking up the “floor”—on a heavy-carpeted room—, but also the sound coming through the 2 heads of the floor tom. This mic was certainly useful for certain songs and added a different color to the overall sound.
