audio to trigger (+ to MIDI?)

[John Speth]

> > I would be interested in a similar sort of DIY project to allow the
> > triggering of MIDI devices using acoustic drum triggers or
> recorded audio,
>
> This does sound interesting. I am interested in interfacing real live
> drums with a modular synthesizer, triggering sounds and perhaps
> processing the drum sounds with a drum kit.
> Does anyone know if this has been done or have any ideas for the
> triggering circuitry?

Yes!  I've done this with my buddy's drum set.  I used piezo crystals
driving some special simple circuitry that I designed to provide triggers
for my Prophet.  The Prophet was programmed to make drum sounds.  You can
build or get a trigger-to-midi controller too.

For the transducers: I got a few piezo buzzers and took out the
quarter-sized peizo element inside.  I soldered a wire on each side, I
potted each in a silicon "button" for which I made a clay mold to do the
potting.  Let it cure and trimmed it with a knife.  The button had a pigtail
that I added a 1/4 inch plug.

For the circuitry: If I remember right, the crystal gave off a ringing short
duration burst of about 50V max.  This made the circuitry simple because all
I had to do was limit the voltage with diodes and trigger a CMOS gate setup
as a one-shot.  It was extremely simple and I made a 3 channel gadget that
ran on a single 9V battery.

If anyone wants more info, please email me.

John Speth
Object Engineering, Inc
mailto:johns at oei.com