Getting the sensitivity right was the hardest part. The peizo transducer is glued to the back of a peice of sheet metal, which is sandwitched between two mouse pads. Anywhere the metal is struck, the piezo will pick it up and send a voltage spike to the dm5. Naturally, this means that sensitivity will decrease towards the edge of the drum, which is sort of how real drums react anyway. The piezos have a surprisingly wide range of sensitivity. There is a bit of a hotspot in the middle if you strike the piezo directly, but I've noticed similar problems with even the expensive brand named rubber pads. The original test pad I built had horrible sensitivity and a big hot spot problem, but I found ways to make the pads better as I went along. If I was going to build another kit I would spend more time getting a prototype pad right first. I kind of rushed the process so the pads I built last (snare) have most of the bugs worked out, but the pads that I made first (mid/floor tom) don't react to playing quite as well. I will probably hve to rebuild the inferior pads one of these days to bring them up to the quality of the rest. I'm convinced that with some more experimenting these pads could be even better. For the absolute best sensitivity and control however, you have to go with mesh heads. There are some great mesh head designs on the edrum for free site, but they are quite a bit more involved.lebaron wrote:But how exactly does the velocity sensitivity work? That's gotta be the most important consideration when making one of these homemade midi generators.
The Dm5 does all of the dirty work converting voltage levels to midi. It does a really nice job and gives you a lot of control over the signal from the piezos. There are plans for DIY trigger to midi units floating around on the net, but at the low price that you can get a dm5 for it was a no brainer.lebaron wrote: I understand the principle of piezoelectric transducers but how to convert this to midi and get it into my host.
Before I had the Dm5 I would plug the piezos directly into the audio inputs of my daw. There a a varienty of plugins that will convert the voltage spikes to midi. I was using KTDrumTrigger at the time and it worked pretty well. There are lots of advantages to using a dedicated hardware unit for this task though. For one, you need a separate audio input for every pad. I have 8 inputs on my delta 1010, but most people are probably working with far fewer. And This is just a job that hardware does better; less latency, more control, higher sensitivity.
The coolest thing about this setup is that you can connect peizos to just about anything and play it as a drum set. I've been thinking about taping piezos to pieces of cardboard and hiding them underneath my clothing. That way, I could play myself as a human drum machine!
