Plaka is a physical modeling synthesizer for graphics tablets. It models the friction between a sharp-ended object and a uniform slender bar, and is designed to be used with a graphics tablet as the performance interface.
Minimum system requirements
Plaka works with Scala scale files and comes with a small selection of scales (see the "Scales" folder under the application folder). Visit the Scala web site to get the most up-to-date Scale Archive that includes more than 3500 scales you can use with Plaka.
1 If your sound driver does not support ASIO, try ASIO4ALL.
2 Limited testing under Windows Vista; see release notes in the installer or in the application folder.
The main functions of Plaka can be accessed via the buttons at the top of the main window. These buttons are Open Scale, Parameters, Scale Contents, Settings, Help and Restart Audio. The functions can also be accessed via keyboard shortcuts. These are shown in parantheses wherever applicable, e.g. (F5).
The Restart Audio button is normally not visible. It appears only when the audio engine is temporarily stopped due to user request (F6) or excessive processing load.
The basic workflow of Plaka is as follows:
1. Open a scale file by clicking the Open Scale button (F2). Plaka will load the scale and draw a bar for each tone in the scale.
Plaka is now ready to play. To produce sound, "scratch" the metal bars with your tablet pen. How much you press down the pen on the bars and how quickly you move the pen will affect the sound produced. To produce sustained vibrations, scratch the bars until enough energy has built up and then quickly lift the pen. To dampen the vibrations, press the pen onto the bars without moving it.
2. Change the synthesis parameters (or manipulate the scale) by clicking the Parameters button (F3). The Parameters panel will appear in the left portion of the main window.
Initial Frequency is the fundamental frequency of the first tone (1/1) in the scale. Repeat scale downwards/upwards... fields will cause the scale to be extended into lower or higher "octaves". If the Repeat the first and last tones of the scale box is checked, the first and last tones will be repeated when extending the scale.
Object Type determines the vibration modes of the bars. When Uniform Slender Bar is selected, the frequencies of the modes are calculated algorithmically. The amplitude of the modes are calculated according to the Mode Weighting formula. When Load from file is selected, the frequency and amplitude data is loaded from the file selected in the drop-down list.
Plaka comes with a small sample of vibration mode files (see the "Vibration Modes" folder under the application folder). See the Vibration Mode File Format section for more information on constructing your own vibration mode files. (Note: The algorithm used in Plaka may not be the best match for the objects or instruments described in the included vibration mode files)
End Conditions determine the amount of vibration that occurs at and towards the ends of the bars. If the object type is Uniform Slender Bar, it will also determine the frequencies of the vibration modes. When Both ends free is selected, there is no damping at the ends. When One end fixed is selected, the top end of the bar is much harder to "excite" than the bottom end. When Both ends hinged is selected, both ends are somewhat harder to excite than the middle of the bar.
Vibration Mode Limit specifies the maximum number of vibration modes each bar can have. This will affect the timbre of the sound produced and the amount of processing load (lower the limit to reduce processing load).
You must click Apply (F5) to see the effects of the changes in the parameters explained above. Changes in the last two parameters are effective immediately.
Resonance controls how long vibrations are sustained. This can also be adjusted using the middle and right mouse buttons. (Tip: Assign these buttons to the buttons on your tablet pen to adjust resonance while playing)
To the left of the Resonance slider is the main volume slider. To reset the volume level, click the speaker icon.
3. To see the contents of the scale file you opened, click the Scale Contents button (F4). The Scale Contents panel will appear in the right portion of the main window. To learn more about the Scala scale format, visit the Scala web site.
4. To change application settings, click the Settings button (F12).
On the Sound page, you can choose which sound device you want to use with Plaka and whether or not the sound produced should be in stereo.
On the Input page, you can adjust the rate of the change in the Resonance slider when using mouse buttons, and which mouse buttons to use for raising and lowering resonance. You can also force Plaka to work with a standard mouse by checking Apply pressure with the left mouse button.
On the Display page, you can specify how the bars are drawn on screen and whether or not volume and pressure level displays should be turned on.
5. To show/hide the toolbar, press F9. To show/hide the status bar, press F10. To use Plaka in full screen, press F11.
Vibration mode files are used for describing objects' vibration mode frequencies and amplitudes. Plaka calculates the modes for uniform slender bars. Other objects can be loaded into Plaka if their mode frequency and amplitude data is available. Plaka includes sample vibration mode files in the "Vibration Modes" folder under the application folder.
The extension for vibration mode files is '.vmod'. The file format is in plain text. Each line describes a vibration mode. On each line are the mode frequency's ratio to the fundamental and the mode's amplitude ratio to the fundamental, separated by a comma. All white space is ignored.
For example:
1, 1
2.57, 0.5
4.1, 0.33333333
8.71, 0.25
This describes an object with 4 vibration modes. Mode frequency ratios are 1, 2.57, 4.1, 8.71, and amplitude ratios are 1, 0.5, 0.33333333, 0.25, respectively.