Trigger pad drumming.

Keyboards, Synths, Samplers and Groove Boxes.

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Re: Trigger pad drumming.

Postby Plink Floyd » Fri Aug 24, 2012 5:49 am

So, you've all been dying to know how Zendrum pads are constructed, right?


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Wut? I'm the only one? Well, since I marked up and labeled this nice drawing, I'll just post it to myself then. :sniff:


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I wondered how they minimized cross talk (false triggering of adjacent pads).

I distilled this bumf from their patent on line:

"The transducers are covered by a rigid support member that comprises a cap and side wall element. Since, in the preferred embodiment, the transducer support members are round, side wall element is cylindrical and cap is circular. The piezoelectric transducer is conventional in nature and mounted to an annular ring made of dense cardboard, Bakelite or similar supporting material.

Annular ring is held in place by an O-ring that keeps annular ring urged up against cap. This provides an air space, indicated below piezoelectric transducer in the volume surrounded by O-ring.

A resilient support member is preferably embodied by a slug of neoprene foam. This is cut and sized so as to fit very snugly within the interior of side wall element so that the neoprene foam resilient support member will stay in place and keep O-ring seated against annular ring.

A disk of the hook element of hook and eye fastening material is glued to the bottom of neoprene resilient support member. A well is formed in top surface of main body at each transducer location. In the bottom of the well, a corresponding disk of eye material is glued in place. A hole passes through the bottom of well through which wire pair from piezoelectric transducer extends. It should be noted that the resilient support member is sized so that there is a gap between the bottom of side wall element and surface. This prevents the rigid support member from striking surface when it is hit to be activated during playing of the instrument."

The inventors of the present invention believe that the combination of resilient support member and hook and eye material are principally responsible for the improved isolation and thus, improved cross talk characteristics of the transducer shown. Furthermore, it is believed that employment of O-ring assists in reducing the response of piezoelectric member to external acoustic stimuli that are transmitted through cap and side wall element. It is further believed that the air space that is provided by O-ring assists in improving the sharpness of the velocity characteristics that are obtained by the preferred embodiment of this transducer.
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Re: Trigger pad drumming.

Postby christianrock » Fri Aug 24, 2012 2:30 pm

Oh my, those things are expensive.

And I had no idea they existed...
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Re: Trigger pad drumming.

Postby Plink Floyd » Fri Aug 24, 2012 9:17 pm

christianrock wrote:And I had no idea they existed...
You should check out the video in this poast. I think (without actually ever having even seen one in person) that they are probably the best, at least for just playing drum parts expressively.
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Re: Trigger pad drumming.

Postby Plink Floyd » Fri Mar 29, 2013 3:49 pm

Well, here's where I am so far on the diy front:

Image

It sort of works, inasmuch as I can get the Arduino to clock the muxes, and they do indeed wrangle analog pulses to the ATMega328 on the ARD board. But that's about where I'm hitting the wall right now.

I think the code is wonky. Even if it loaded and worked smoothly (which it doesn't), it won't properly convert the inputs into midi notes. I'm also afraid that, even if it did work as advertised, it will have too much latency. (Shouldn't a 16 Mhz proc be able to scan 48 analog inputs?) I'm thinking I might just have to abandon the ARD platform and follow ePup down the AVR Studio road.

On the plus side, I think I'm onto something quite good in the trigger pad department (the secret bits at the other end of the ribbon cable). I just need the computery part to work so I can test for sensitivity, playability, crosstalk, and such.
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Re: Trigger pad drumming.

Postby gregwar » Fri Mar 29, 2013 4:39 pm

i'm impressed !

i posted a video of a guy who built his own drum pads a while ago don't remember what thread tho

basically the zendrum pads seem to be the best in the business. i wanted one altho i didn't try it but the price was just too much for me'

i got an akai mpd 32 instead thinking that would be the beezkneez but it really sucked imho lol

the pads were really stiff even after pounding on it for like 2 years and it turns out i suck at finger drumming lol

also assigning the pads to kits in battery was always a pain. i ended up using the caps lock keyboard in logic (like the typing keyboard on my laptop becomes a music keyboard when you hit caps lock) and the odd time using a keyboard to play drum parts.

mostly tho i like to program the drums on a grid like ultrabeat. i can then save the midi file, manipulate the timing with various swing/shuffle templates and swap out samples or synthesize new ones
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Re: Trigger pad drumming.

Postby ElectricPuppy » Fri Mar 29, 2013 4:55 pm

Looking good, Plink!

While I was hot and heavy with my keyboard controller project, I discovered that scanning and MIDI-fying takes longer than I really expected. I was running an AVR at I think 16 or 20 MHz and all I had it do was do an 8x8 matrix switch scan at about 1ms per scan. It works, but the overhead of tracking velocity (which meant comparing against the previous scan) and generating the MIDI from it (not hard, but I pick out the notes that had actually changed, and scale the velocity time to MIDI velocity) meant that I was keeping the thing seriously busy for most of its time! And, it turned out, 1 ms actually isn't fast enough for goot sensitivity at high velocities! I need to run about a 1/4 of that speed (250 us/scan) to really be good.

Bottom line: You may want to think of a scenario where you totally dedicate a processor to doing nothing but scanning/converting, and then pass only interesting info to another processor that does all the rest of your work.

This appears to be what keyboard makers used to do. For example, the Polaris has a totally dedicated process just for keyboard scanning, and so does the Waldorf XTk. It wouldn't' surprise me if this were common.

Also, programming: I like to think I know a little about embeded programming, would you like another pair of eyeballs on your code if you need help?
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Re: Trigger pad drumming.

Postby Plink Floyd » Fri Mar 29, 2013 8:28 pm

ElectricPuppy wrote:Also, programming: I like to think I know a little about embeded programming, would you like another pair of eyeballs on your code if you need help?
You are a scholar and a gentlepup! I Thank You! :cry:

But it's not my code, it comes from the microdrum guy. I could email him about it, but since he's not charging anything for sharing the project, I kind of hate to bother him. And furthermore, I suspect that even if it was fully working as advertised, the latency would still be too bad. As you suggest, I fear I need moar power.

But, I think I'll contact him just the same. Worst case, he'll not answer...
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Re: Trigger pad drumming.

Postby ElectricPuppy » Fri Mar 29, 2013 8:39 pm

Moar Power is always the correct answer! :thu:
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Re: Trigger pad drumming.

Postby Plink Floyd » Wed Apr 10, 2013 10:51 am

So, Pup...

For your midi keyboard thingy, did you write all the code from scratch, or did you find some of it already in the can, or what? And, I suppose you coded it in C? With Atmel Studio IDP?

If you could be presumed upon, I would hang breathlessly on your every word if you held forth in the style of ATMega for Dummies, pls.

And you other nerds are welcome to chime it too, if you please. As I am teh null zero noob coder, I can but learn something from all you programmatical pundits.
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Re: Trigger pad drumming.

Postby ElectricPuppy » Wed Apr 10, 2013 5:47 pm

Wrote from scratch. In C, 'natch. :grin: I used Atmel's AVR Studio, which at the time I think was version 3 or 4. It's been, what, a couple of years now? I'm sure they've got a much more up-to-date studio-thingie by now.

One of the tricks of embedded development is that you don't start with a puny system. You start with an over-powered system (moar CPU power, moar RAM, moar ports, etc) and once you get your bearings on that, THEN you see about downsizing to something smaller/cheaper. I thought I was doing that with the AVR part I picked, but (surprise!) it turned out not to be.

As far as programmatical punditry goes... I don't have a reserve of pithy advice just waiting to be unleashed, unfortunately. :grin: But, if you show me something or have a specific question, I can be a lot more helpful. Or, at least I think I can be a lot more helpful. Or smug. Or something.
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Re: Trigger pad drumming.

Postby Plink Floyd » Thu Apr 11, 2013 10:53 am

ElectricPuppy wrote:One of the tricks of embedded development is that you don't start with a puny system. You start with an over-powered system (moar CPU power, moar RAM, moar ports, etc) and once you get your bearings on that, THEN you see about downsizing to something smaller/cheaper.
Sounds legit. I was hoping to delve into it this morning but the bastitds wanted me to work.

:mad:

Maybe an array of ATtiny828s would be a good way to wrangle forty or fifty peizo inputs... I'll have to see if they have any injection current conditioning...

But, if you show me something or have a specific question, I can be a lot more helpful. Or, at least I think I can be a lot more helpful. Or smug. Or something.
Thankee! I'll most certainly bug you soon.

:wave:
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Re: Trigger pad drumming.

Postby ElectricPuppy » Fri Apr 12, 2013 5:06 pm

Last night I went over the AVR's site to see if their Studio runs on Linux.

:mad: No. FEH, I say!
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Re: Trigger pad drumming.

Postby Plink Floyd » Tue Apr 16, 2013 4:21 am

ElectricPuppy wrote:no Linux feh!
Wut? Just because you can't use your Linux-only laptop?
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Re: Trigger pad drumming.

Postby ElectricPuppy » Tue Apr 16, 2013 4:28 am

Well... yeah! I don't want to say I've become a Linux fanboi, but I haven't missed ol' Windows on my lappy. In fact the uptime on my Ubuntu install at the office is over 60 days. Haven't had to boot over to Windows for anything.

My only remaining Windows machine here is the desktop PC in Ye Olde Studio for Sonar. I guess I'd have to do AVR stuff in there, but that's darn inconvenient. I'd rather use Teh Lappy in Teh Garage, but it's got Teh Linuxes!

FEH! FEH, I say!
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Re: Trigger pad drumming.

Postby Plink Floyd » Tue Apr 16, 2013 5:13 am

ElectricPuppy wrote:My only remaining Windows machine here is the desktop PC in Ye Olde Studio for Sonar. I guess I'd have to do AVR stuff in there
Yeah, you don't want to go flipping hot solder around yer Space Vag.

Is Atmel AVR Toolchain for Linux comparable to Studio?
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Re: Trigger pad drumming.

Postby ElectricPuppy » Tue Apr 16, 2013 5:54 am

Ah yes, that's better. It's the tools, just without the fancy IDE wrappings. But I dont see mention of a debugger... ? Probably that's a whole 'nother thing. I believe that's built into the Windows IDE. For Linux we typically have to use GDB. It's not bad once you get used to t.
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Re: Trigger pad drumming.

Postby ElectricPuppy » Tue Apr 16, 2013 5:55 am

Hmpf. I just realized that all my work was on an old HP Windows laptop that died a couple of years ago (which is why I have the Ubuntu laptop now). I'll have to yank the drive to retrieve my files. Feh.
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Re: Trigger pad drumming.

Postby ElectricPuppy » Tue Apr 16, 2013 5:56 am

And once more with feeling (just because):

Feh!
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Re: Trigger pad drumming.

Postby Plink Floyd » Tue Apr 16, 2013 6:06 am

ElectricPuppy wrote:I'll have to yank the drive to retrieve my files. Feh.
If it's a decent sized drive, put it in a handy portable USB case.Those things are cheap, like five bucks on ebay.

ElectricPuppy wrote:For Linux we typically have to use GDB. It's not bad once you get used to t.
Whatev u say. It's all gnu to me. :idk:
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Re: Trigger pad drumming.

Postby ElectricPuppy » Tue Apr 16, 2013 4:10 pm

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