Yamaha DTXpress/DTXplorer/DTXtreme

Well, I have uploaded my best guess to the files section as "Rock Band
interface".  The components aren't critical - use any general purpose
NPN transistor.  I can only guess at what's inside the Xbox/PS3, but I
am guessing a simple pull-up resistor internally.  The circuit has no
power so it won't be able to do any harm - it will just either work or
not.

There is no difference between the kick and cymbals in principle -
they both generate a voltage from a piezo.  However, there are subtle
differences apart from signal size.  There is an adjustment pot on the
KP65 - try turning it up.  The other differences are the ringing that
you get on the cymbal signal so it will generate positive & negative
pulses.  The KP65 is more damped, from memory.  So it may be
worthwhile reversing the connections of the KP65 (top to sleeve and
sleeve to tip) to swap the pulse polarity & see if that makes it work.

HOWEVER, I WOULDN'T RECOMMEND PUTTING PIEZO SIGNALS INTO EQUIPMENT
THAT ISN'T DESIGNED FOR THEM.  I know people seem to get away with it,
but there is a risk.  The voltages can be quite high and could blow up
what you are plugging it in to.  Something like my circuit provides no
power to the box, so can do no more than a switch.

Keith.