February 27, 2008

Lil' Dipper...

by Chris Randall

Judging from the comments in the last post, this is obviously something that like eight people find interesting, so I just thought I'd throw my mock-up up so you can see what the hell I'm up to.

In spinning around in my office chair, pondering what it was exactly that I needed in a MIDI drum pad trigger thing, I thought it would be redundant to have more than eight actual pads, considering the amount of post-production I do and the actual method I generally use to program drums. In order to use materials on hand (i.e. an Arduino) I knocked that down to six, since an Arduino has six analog inputs, thus obviating any need to do any shift register bullshit just to get an extra two sounds.

I also thought that it would be nice to have a couple buttons for momentary CC. These could be used for any number of things, depending on need, but they'd be handy to have. Since an Arduino has a whole shitload of digital I/O, I could actually have far more buttons, but frankly I couldn't see the need. Three is fine. (I might go to four, but I doubt it.)

So I threw together a quick mockup in 3DS Max, since visualization is 9/10 of creation, and that's how I visualize. That mockup is pictured above. I'm still not 100% sure how I'm going to do the pads, but my thought is thus: using a 1.25" forstener bit, I'll punch divots in the appropriate spots. In this will go a 1.125" rubber grommet. On top of that, a 1.125" zinc or tin disc. The piezo pickup will be epoxied to the underside of this. On top of that, I'll put a 1.25" (or slightly smaller) disc of rubber. In this manner, I'll have a nice surface for tapping, and still maintain good isolation between the pads. Some experimentation will be in order there. I see many methods on the Interwebs, and I've tried a few of them in the past, but nothing for pads this small.

Since the actual unit is a solid block of walnut, it should be dense enough to minimize crosstalk. Again, we'll see about that. I can always program the Arduino specifically for my tapping range in order to get the crosstalk out, so that should be fine.

Today I roughed out the wood, and hollowed out the underside which will hold the electronics. Since this is specific to my needs, I don't need to have it transmit on every MIDI channel under the sun; hence, I'm able to get away with just a MIDI out and a power port when all is said and done.

Fun little project, anyways, while I work up the courage to buy the rest of the shit I'll need for the Jagro.



Page 1 of 4

Feb.27.2008 @ 1:54 AM
That seems like a nice project yeah - I was actually thinking about buying the Zap but the price is not so hot so I might eventually go down the same route myself. Either the Arduino or the UCapps Midibox platform seems like a safe bet, although Midibox is kind of overkill for just a few pads and buttons I guess.

Feb.27.2008 @ 4:33 AM
Arduino was even cheaper than I remember, I guess I'll order one soon and start experimenting myself.

Seems like you'll need bit of trigger amp / processing electronics to get clean trigger signals out of piezos though. Either that or some clever extra lines of code. I wonder if there will be timing issues to tackle in addition...


Feb.27.2008 @ 4:34 AM
Looks really neat, I wish more manufacturers would take a less-is-more approach.

Though in my role of asker-of-dumb-questions i'm obliged to ask: I thought a denser block of wood would transmit more crosstalk? Isn't that why 'toneful' guitars tend to be made of harder woods, more transmission of sound?


Feb.27.2008 @ 6:29 AM
Bonus for live use: Use it to beat hecklers to death.

In all seriousness, that's a pretty slick design. A nice departure from the typical DIY controller design philosophy (e.g. Midibox) of, "what else can I put in?".
Looking forward to seeing the finished result.


Feb.27.2008 @ 7:56 AM
I'm actually fascinated by shit like this and wish I had the skills, time and, honestly, technical intelligence to do projects like this myself.

I just have nothing to add to the conversation. Well, other than, "Dude! Cool!"

But I'm looking forward to watching the process and the eventual YouTube video.


Feb.27.2008 @ 8:42 AM
I too like the simplicity. The Zap just looks like overkill for the majority of people. As far as pad placement goes, do you think 2 arcs with 3 pads might be more ergonomic than having the square in the middle? Basically 2 handles and no cup for your dipper. Then you could have it on a tabletop and your hands could rest on the wood on both sides.

Grind Luck.


Feb.27.2008 @ 8:45 AM
Damn it, after reading this post I've been thinking about controller / gadget ideas that would be pretty easy to prototype with Arduino and now I'm so full of bad ideas I actually need to get one or two of those ordered ASAP, along with a bunch of leds, buttons and piezo elements.

Unless my increasingly obsessive mind starts looping some other "good" idea by tomorrow, which is the more probable scenario...


Feb.27.2008 @ 9:12 AM
magnificent. velocity sensitive?

Feb.27.2008 @ 11:43 AM
That's good design.

Feb.27.2008 @ 11:45 AM
Chris Randall
@vae: A zener diode running to ground from the hot of the trigger, plus a resister is all that is needed. Just enough to keep the triggers from going hot enough to burn out the Arduino if you, say, drop it. The rest can be done in code.

@wquoyle: In this case, the object of the exercise is to keep the unit from jumping about, and causing false triggers by actually hopping on the playing surface. The wood won't be transmitting much, because of the softer rubber washers. I _think_ it'll be all right. Pondered it for a while, and was gonna make it out of ash or alder, but changed my mind. The wood is the easy part, though, and I'll assemble and test it before I finish the wood; won't take but an hour to cut and rough a new blank. All of the Zendrum stuff is made out of the absolute densest hardwoods, and I figured he had some experience in that matter.

@kRYPToPS: The layout is because of thus: I'm left-handed, so most of the triggers are on the left side. The three buttons can be held down with the three outside fingers of my right hand, and I don't lose any playing ability at all. That was my thinking, anyways. I made sample layouts on paper and sat here rapping away on my desk for quite some time to come up with that layout.

@kramer: Yup.



Page 1 of 4



Sorry, commenting is closed for this blog entry.