On a taiko drum, in addition to striking the head (ドン) you need to be able to play rim shots (カラ). To make a rim, I cut a gap into the masonite. The rim needed to be as wide as a piezo sensor. I used GE silicone adhesive to fasten the piezo sensors to the drum head and rim, then wired each set in parallel (observing polarity) and then to a connector on the rim. I had to change the Arduino/nunchuck interface a little to handle two channels efficiently. That may be the subject of a later post.
In this new configuration, I seem to have trouble with single hits being detected as multiple. Reducing the number of sensors on the head helped. Also increasing the padding on the head of the drum helped. I bought a bunch of mouse mats for that purpose. Still, I think either the masonite board is resonating, or, more likely the board is bouncing up and down on the foam. The best fix I can think of for this is to glue them together, but if I do that, I will no longer have access to the underside of the head, so making changes is going to be difficult.
Anyway, here's the result:
