Slendro and Pelog: The Two Tuning Systems of Javanese Gamelan
The slendro pelog scales behind Javanese gamelan
Javanese gamelan music uses two tuning systems, and the slendro pelog pair is the first thing to learn about it. Each system, called a laras in Javanese, is a set of pitches that an ensemble uses for a whole piece, and each gives the music a different colour. Slendro divides the octave into five steps of nearly equal size. Pelog divides it into seven steps that mix wide and narrow intervals. A full Javanese gamelan is in fact two sets of instruments, one tuned to slendro and one to pelog, and the two sets are never played at the same time. Below is what each scale is, how the two are built into the instruments and heard in performance, and how a visitor can begin to tell them apart.
What makes a slendro scale sound open
The slendro scale has five notes to the octave, and the intervals between them are so close in size that they are often treated as equal. Because the steps are so even, the scale does not lean toward any one note in the way a Western major or minor scale does. A melody in slendro moves through a regular pattern of steps, and the ear can settle into it quickly.
In Javanese cipher notation the five slendro notes are written 1, 2, 3, 5 and 6, with no 4. The numbers are read in Javanese as ji, ro, lu, ma and nem, and the notes also have older names: penunggul or barang for 1, gulu for 2, dhadha for 3, lima for 5 and nem for 6. Learning these names helps when musicians talk through a piece or when you follow written notation at a rehearsal.
Slendro is further divided into three pathet, or modes: pathet nem, pathet sanga and pathet manyura. Each pathet has its own mood, so two slendro pieces can feel quite different even though they use the same five pitches.
What gives pelog its different character
Pelog has seven notes to the octave, written 1 to 7, and the spaces between them vary. Some steps are wide and some are narrow, and this unevenness is clearly audible, in contrast to the smooth, even steps of slendro. The mix of large and small intervals gives pelog melodies a distinct shape that sets them apart from slendro as soon as you know what to listen for.
Although pelog has seven notes, a piece in pelog usually draws on a five-note selection from them. Like slendro, pelog has three pathet, among them pathet lima and pathet barang, and the pathet decides which five notes form the core of a piece.
Because the seven notes are unevenly spaced, a pelog set has to be tuned with great care. Each instrument must match the others in the set, and the relationships between the notes must hold together across the whole ensemble.
Building the scale into the instruments
Every fixed-pitch gamelan instrument is made to one scale. Saron, slenthem, gender and gambang, the kenong and the kempul, and the suling all exist in a slendro version and a pelog version. A full gamelan therefore contains two sets of most instruments, and the players move to the appropriate set when the music changes from one system to the other.
The plucked zithers solve the problem differently. A siter carries strings on both sides of its box, with one side tuned to slendro and the other to pelog, so a single instrument can serve both systems. The celempung, the siter’s larger relative, is also a plucked zither, tuned an octave below the siter.
There is no single fixed standard for gamelan tuning. Over generations it has become accepted practice that each set is tuned to the judgement of its tuner, and the exact pitches and intervals differ from one gamelan to another and from region to region. Within one set, however, the instruments are tuned closely to each other. That is why instruments cannot simply be borrowed from another gamelan without sounding out of place.
Why an ensemble does not mix the two systems
A slendro set and a pelog set are never played at the same time. The intervals of the two systems are different, so instruments from one set would clash with the other. A piece is performed in one system, and when a programme moves from a slendro piece to a pelog piece, the musicians change to the instruments of the other set.
This separation is one of the most useful facts about gamelan for a visitor to understand. When you hear a piece, you are hearing one scale played by a whole ensemble. The players, the tuner and the instrument makers all work within that system, and the result is a coherent and balanced sound.
How a visitor can tell slendro from pelog
Telling the two systems apart takes a little practice, but there are some clues that help. Slendro pieces move in even steps, with a regular pattern that the ear can follow easily. Pelog pieces mix wide and narrow steps, so the melody has a more uneven contour, with some notes sitting close together and others far apart. A visitor who listens to several pieces in a row will begin to notice the difference.
It also helps to watch the ensemble. When the musicians shift from one row of instruments to the other between pieces, the system has changed. Asking a musician at the end of a performance is a good way to confirm what you heard, because most players are glad to explain the system their ensemble uses.
Listen, too, to the softer instruments. The rebab, a bowed string instrument, elaborates on the melody, and its part follows the scale of the piece. The bonang, a row of small bronze kettles, also exists in both systems, and its bright notes make the shape of the scale easy to hear.
Questions people ask about slendro and pelog
Does a gamelan play both scales?
A full Javanese gamelan does, because it is really two sets of instruments, one in slendro and one in pelog. The two sets are never played at the same time; the musicians use one set for a piece and switch to the other for a piece in the other system.
Does a pelog piece use all seven notes?
Usually not as its core. A pelog piece is built on a five-note selection from the seven pitches, chosen according to its pathet.
Is every slendro gamelan tuned the same?
No. There is no fixed standard, and each set has its own tuning. The pitches and intervals differ slightly from one gamelan to another and between regions, while the instruments within one set match each other.
Can a visitor learn to play in either scale?
Yes, although learning takes time. Students usually begin with the scale that their teacher’s ensemble uses, and they develop an ear for the intervals through repeated practice. Some cultural centres offer short workshops for visitors that introduce the basic patterns.
For the modes that sit within each scale, read about pathet.
Keeping slendro and pelog sets in tune
Both scales require regular care. The tuning of a set has to be checked from time to time, and string instruments need their tension checked often. Because each gamelan has its own tuning rather than a universal standard, a tuner who works on a set has to match its existing character, not an outside reference.
Tuners often work with experienced musicians, because the final judgement depends on how the ensemble sounds together. A tuner may get each instrument right on its own and still need the players to confirm that the whole set blends. This shared work is part of what keeps the two scales alive.
Players also learn to hear the scale before they touch an instrument. Singing a melody in its scale makes the intervals familiar in the voice before they appear on the bronze, and it makes it easier to spot a sour note during rehearsal.
Hearing the two scales in Central Java and Yogyakarta
To hear both systems, attend a performance by an ensemble that owns a full gamelan, where pieces in slendro and pelog can appear in the same programme. Ask at the venue whether a piece is in slendro or pelog, and listen for the difference between the even steps of one and the uneven steps of the other. Watching the players move between the two rows of instruments is often the clearest sign that the scale has changed.
A visit built around the two scales will show you how one ensemble can hold two different worlds of sound, and it will change the way you listen to every gamelan you hear afterwards.
Related guides: kenong, siter, rebab, Caring for a kempul over many years, bonang, celempung, pathet, Central Java Gamelan: Instruments, Tuning and Music.