Regaip "Rego" Sen - Final Project for Music 220a - December 11, 2003
THE DOUBLE-JEGOGAN SYNTH!!!

I created a synth jegogan pair consiting of a Pd patch that inputs MIDI from a given channel and outputs a pair of tuned jegogan samples. The jegogan is a member of the Balinese Gamelan ensemble, and these instruments have a tuning system that differs from the western system in the following ways:

• There is no agreed-upon fundamental pitch (e.g. A=440Hz), so different Gamelan ensembles have different pitches for the same note.
• Most Gamelan instruments are played in pairs that are slightly "detuned" to create 4-8 beats per second (depending on taste) when corresponding notes are simultaneously played.
• There are two different scales, and one is divided into three subscales:
  • Pelog is a 7-note-to-the-octave scale that has been described as close to the white keys of a scale starting at E (E, F, G, A, B, C, D).
    • Selsir a the 5-note sub-scale of Pelog that would correspond to its notes E, F, G, B, C.
    • Tembung is a 5-note sub-scale of Pelog that would correspond to its notes E, F, A, B, C.
    • Sunaren is a 5-note sub-scale of Pelog that would correspond to its notes F, G, B, C, D.
  • Slendro is another 5-note scale. Its pitches have been described as close to A-C-D-E-G, though the intervals are to be roughly equivalent, giving the scale no sense of tonal center.

My synth jegogan patch is more versatile than the traditional jegogan in that it can be adjusted to play in any Gamelan ensemble, regardless of their scale fundamental pitch, or beating taste! In addition, it comes with a dummy jegogan partner who plays after a randomized miniscule delay, and the pair are slightly panned for a nice stereo effect. The main patch has four inlets that correspond to the following controls (from left to right):

1. Choose the MIDI Channel to read from
2. Choose between the 4 scales used in Gamelan instruments: 0=Selsir(default), 1=Tembung, 2=Sunaren, and 3=Slendro
3. Choose the frequency offset, which adjusts the entire scale (+/-) by this number in Hertz. (default=0)
4. Choose the number of beats per second. Default is 5, and traditional ensembles range from 4 to 8.

I obtained exact selsir frequencies from a thesis that measured the notes of each instrument from two Gamelan troupes. I also obtained slendro and complete pelog frequencies directly from sound samples (found here) to extrapolate frequencies for several octaves of each scale and subscale.

The jegogan and most other mallet instruments in a Balinese Gamelan ensemble are played with a mallet to excite a note, and a hand to dampen it. Traditionally, the hand dampens the most recent note just as the next note is to be played (or beforehand), so that only one note is sounded at once from a single instrument. This behavior can by automated with a single table-reader. When a note is turned on, it plays until the next note is turned on. Additionally, the white keys may be hit to mute the instrument before striking another note. The key velocity also translates to volume. Below is a screen shot of a simple patch calling the pd patch, the pd patch itself, and its note-to-frequency-mapping subpatch, scalesel:

Here is a wave file of the following:

Time Sound
:00  Demonstration of a Kotekan melody
:05  Demonstration of muting and key velocity
:16  Scale of Selsir
:24  Scale of Tambung
:30  Scale of Sunaren
:37  Scale of Slendro
:44  Demonstration of frequency shifting
:54  Demonstration of beating effect changing between 4 and 8 beats/sec.

While this instrument can be played alone, multiple controllers can be chained to play on different channels, and opening (and assigning) a patch for each channel will enable the synth jegogans to play simultaneously.

Regaip Sen