OT: DIY Acoustic drum triggers

[Basonsubatomia]

Anyone have any experience/links with building these? From what I've seen of some commericial products like the DDRUM Red Shot and the Roland acoustic triggers, the way to do it is through either foam or rubber contacts tied to a piezo mounted on a little clamp... should be fairly straightforward to reproduce... any experiences/comments would be great.

[MarkB]

I've built plenty of pad triggers, but none to clip onto acoustic drums.

I always used those Remo tunable practice pads - with a layer of rubber inside - and a piezo underneath... works GREAT into any old Alesis, etc for triggering.

Making a clip-on may be a little trickier, but if you can get a small enough piezo, and just find a way to rig it up to the hoop... buffer it with some rubber (not too soft, or it won't transmit the vibration very well) .. just enough to protect it.
"-)

[freebird1127]

What's a trigger? What's it used for?  Never heard of!

[Basonsubatomia]

Yeah, there's seperate drum pad DIY resources galore, but not many on the acoustic trigger... I'm leaning towards the piezo+rubber/foam idea as you said, Mark. Making the clamp shouldn't be tooo hard - I'll just book some time at my old work (small two-man machining shop) and bend some metal into clamp shapes, drill + tap some holes for a tightening bolt and boom! What kind of foam/insulation did you use, Mark? Also the specs on the piezo?

A drum trigger is something that you can either connect to an acoustic drum head (such as what I'm talking about) or on a pad (electronic drums, V-Drums). Either way, it detects hits on the skin/pad and then sends that info to a midi or other controller to play a determined sound. Since it's just a signal transmitting how hard you hit the drum, the sound played could be a synth drum, a hand clap, or any other sample (depending on the controller that's used).

[Mark Hammer]

Evan,

A drum trigger will output the information needed by a drum synth module when a pad or sensor is struck.  That "event information" could be any or all of the following:
- a brief standardized trigger pulse at the start of the event
- a gate signal that lasts for some fixed period of time or until the piezo sensor has recovered in some manner
- a control voltage proportional to the velocity with which the pad was struck, sort of like a scale-able trigger pulse
- an envelope signal that incorporates both the control voltage created by harder strikes, and some adjustable decay rate

Which of these gets used how depends on what it is you're driving.  For instance, there were a number of circuits in the mid-80's for interfacing your Atari 512ST or whatnot to a set of drumpads.  The interface simply told the computer "play this sound now" using a trigger.  Normally, there is some sort of Schmitt trigger or comparator deal in the circuit which allows you to compensate for stick velocity by turning the sensitivity up or down.

Decen drumpad/trigger assemblies use a combination of stiff and pliable surfaces.  You need something with a little give if it is going to absorb the shock of a stick-hit (and your wrist needs for some of the energy to be absorbed by the struck surface).  If there is too much give, it doesn't feel right and suspect the piezo disc deforms differently and may yield a slower rate of initial change.  I made some with galvanized discs (that fit on junction boxes) as the base, and sandwiched the disc between two sheets of cork, which were glued to each other and to the metal disc.  Seems to work fine, and certainly feels reasonable.

Clipping something to the edge of the drum is tricky because of propogation delay.  The stick hit has to transmit a pressure wave that travels the drum head and out to the shell where it is picked up.  Those few milliseconds travel tiem can be a little offputting, particular when combined with the few milliseconds for MIDI-decoding that may be involved.

[gez]

Not exactly what you're after, but Everyday Practical Electronics are going to have a schematic for a 'Bongo Box' in their next (July) issue.  According to the blurb it's triggered by drumming your fingers on the box.  

Can't wait for this one!

www.epemag.wimborne.co.uk

[Nasse]

:shock: I once used quite thick (15...20 mm) and good quality rubber mat on thick chipboard. The rubber mat was leftover from big building site, they used such mat under huge concrete slabs, maybe not very cheap

Was quite nice bouncy feel like real drumhead, but I am no drummer

[Mark Hammer]

http://www.paia.com/drumsens.htm

[StephenGiles]

Try here:
http://edrum.for.free.fr/modules.php?name=Content

[DouglAss]

I've used the Radiashack buzzer pickup hooked up to mesh heads on a Pearl rhythm Traveller set -- they, for the most part, have worked as good or better than the Pintechs that I've used

The mesh heads feel abbout a jillion times better to me (by "better" I mean like an acoustic drum situation - so I'm biased to an "acoustic" feel)

there are few articles out there -- I'm just not sure where

you couple the element through some closed cell foam (yellow Nerf projectiles are a common one)

An angle iron is used on the inside of the shell as a mount

You can even do a multi-zone this way

Two things I have found about this set up

1) while it is typical to just run the pickups into the brain, I suggest running is through a small preamp/buffer so you can trim the level easily instead of messing with response curves in the brain (though I suggest this even with regular triggers)

2) you can use these as contact elements to mix in a little mechanical "hit" --  I don't think you'd want to use it as a primary sound (maybe so with EQ), but it does add a little "mechanical sound" to the event and helps deal with extended technique like rimshots
I don't think this would work as well with gum rubber pads though