It might be old news for you if you follow discussions on the
forum. Thanks to Synthex MegaDrum is now even simpler to build if you can buy
74HC4851 or MAX4558 instead of 4051. Using these ICs you can omit all BAT85
diodes and
100 Ohm ESD protection resistors. It is 96 less discrete parts
for 32 inputs version of MegaDrum! Follow these threads:
http://www.megadrum.info/forums/viewtopic.php?f=3&t=96
http://www.megadrum.info/forums/viewtopic.php?f=3&t=108