Watching Lee Ritenour DVD and notice the drummer bass drum sound demonstrated incredible tight low-end. Now I know why. The drum kit used subkick which is a microphone for bass drum.
6.5" Speaker/Diaphragm
Yamaha takes a 6.5" speaker and shock-mounted it into a 10" drum shell and reverse-wired it to an XLR jack to convert the speaker diaphragm into a microphone diaphragm. This allows Subkick to pick up the low-end that a normal microphone can't.
Mounting the speaker into the shell focuses the sound to direct the signal into the diaphragm. Using our shell makes the Subkick as easy to use on the road as it is in the studio.