Take me to the Steps

SportsWeek_Badge_bur01With a piezo disc and some basic electronic components, any surface can be transformed into a giant musical controller and played through your iOS device using open-source software. In this tutorial, we will learn how to sonify skateboard elements such as grind rails, half-pipes, launch ramps, and fun boxes and turn any skate surface into a musical playground. Customize your skateboarding experience with your own sounds and create your own musical composition/performance/sound art.

Skatehack action

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skateramp

You will need:

skatehack-spread

How does it work?
The piezo disc connects in the mobile device’s input jack and triggers sounds when hit using MobMuPlat’s open source software platform. Audio signals from the piezo are converted into .wav file triggers. MobMuPlat is an open-source software platform which runs Pure Data on iOS devices. With MobMuPlat you can program which sounds to trigger inside the app with .wav and .aif file extensions.

For more details, contact info@skatehack.org

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Project Steps

Cut and strip a 3.5mm stereo mini jack cable

Cut and strip a 3.5mm stereo mini jack cable.

Test Ground, Audio L and Audio R wires with a multimeter. Separate ground wires with Audio L and Audio R wires. Twist both Audio L and Audio R wires together.

Wire to piezo disc

Connect Audio L and Audio R to the black wire of the piezo disc and ground to the red wire of the piezo disc. Insert a 1K or 800 Ohm resistor between the ground wire and the Audio L and Audio R wire. Most devices will not recognize the piezo as an external mic, so we trick the device into thinking it is an external microphone by running a 800 Ohm or a 1K resistor between the mic and the ground wire.

Wrap in copper tape or solder the wires together. Add additional electrical tape to insulate the cables.

Download MobMuPlat

MobMuPlat is a standalone iOS app which hosts and loads an audio engine using the graphical programming language, Pure Data (PD).

Download MobMuPlat

Download the sample SkateHack Patch here and drag it into your “Documents” folder of iTunes under the MobMuPlat application. (Note: Drag the contents of the folder, not the folder itself.)

Insert Piezo into Headphone Jack of iOS device

Insert Piezo into the “Mic” Input of the Audio and Mic Splitter. Run the MobMuPlat app on your IOS device.

Test Piezo is recognized as an “external microphone.”

Open MobMuPlat on your iOS device

Tap the Info Button

Select Audio/MIDI button on bottom of screen. This will open the Audio/MIDI settings page.

Scroll down to Input: It should read: “Headset Microphone channels: 1”

If your device is recognizes the Mic Input as “Headset Microphone” you have successfully connected the piezo. If not, double check your connections and make sure you wired your Audio L Audio R and ground connections properly.

In the Audio MIDI settings screen, tap on “Select Document” Scroll to the downloaded Skatehack sample patch from Step 2. Open the file “skatehack.mmp”

You piezo disc should now trigger the sample 1.wav file. Adjust the audio input sensitivity and the output volume using the sliders Tap “Randomize” to scroll through 6 different audio files.

To create your own custom sounds. Connect your iOS device to Itunes. create an audio file and label it 1.wav, 2.wav. Under the Itunes folder, drag the newly created files into the “Documents” section. This will replace the sample files with the new files.

Embed Piezo Trigger on Ramp

Connect a portable speaker to the “Audio” output of the Audio Mic Splitter cable.

Attach piezo to trigger surface.

Skate and destroy.