Gamelan Elektrika: An Electronic Balinese Gamelan

Laurel S. PardueResponsive Environements,

MIT Media Lab75 Amherst St E14-548Cambridge, MA 02142

punk@mit.edu

Andrew Boch321 Highland Ave

Sommerville, MA 02144

Matt BochHarmonix

625 Mass. Ave, 2nd Fl.Cambridge, MA 02139

Christine Southworth65 Turning Mill Rd.

Lexington, MA 02420southsea@kotekan.com

Alex Rigopulos∗

Harmonix625 Mass. Ave, 2nd Fl.Cambridge, MA 02139

ABSTRACTThis paper describes the motivation and construction ofGamelan Elektrika, a new electronic gamelan modeled aftera Balinese Gong Kebyar. The first of its kind, Elektrika con-sists of seven instruments acting as MIDI controllers accom-panied by traditional percussion and played by 11 or moreperformers following Balinese performance practice. Threemain percussive instrument designs were executed using acombination of force sensitive resistors, piezos, and capaci-tive sensing. While the instrument interfaces are designedto play interchangeably with the original, the sound andtravel possiblilities they enable are tremendous. MIDI en-ables a massive new sound palette with new scales beyondthe quirky traditional tuning and non-traditional sounds.It also allows simplified transcription for an aurally taughttradition. Significantly, it reduces the transportation chal-lenges of a previously large and heavy ensemble, creatingopportunities for wider audiences to experience Gong Ke-byar’s enchanting sound. True to the spirit of oneness inBalinese music, as one of the first large all-MIDI ensembles,Elek Trika challenges performers to trust silent instrumentsand develop an understanding of highly intricate and inter-locking music not through the sound of the individual, butthrough the sound of the whole.

Keywordsbali, gamelan, musical instrument design, MIDI ensemble

1. INTRODUCTIONGamelan has been performed for hundreds of years in In-donesia. The term gamelan is a general reference to a mu-sical ensemble which can take many forms. One of themost famous is the metalophone instruments of the Bali-nese Gong Kebyar. It is renowned for the shimmer, intricateelaborate melodies and the tight interlock and togethernessof the playing ensemble. Uniquely in Balinese gamelan, theinstruments come in pairs, where each instrument is slightly

∗The company Harmonix was not involved in this project.

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out of tune with the other half of the pair resulting in acous-tical beats. A characteristic of Balinese composition is theinterlocking of parts; a single line is regularly split betweentwo instruments and two players resulting in quick, intri-cate rhythms. Additionally, gamelan is based on differentversions of pentatonic tuning with each gamelan set havingits own related but distinct tuning. No two gamelans arethe same [4].

Figure 1: Galak Tika’s gangsa and reongs includinginstruments from the Beta gamelan at the rear.

Balinese Gamelan is immensely popular in Bali, whichhosts large national ensemble competitions. Study of theinstruments first spread to the US in 1958 [9]. Balineseworks are through composed and taught aurally. The Mas-sachusetts Institute of Technology hosts Gamelan GalakTika (GGT), founded in 1993 under the direction of EvanZiporyn. With regular performances around the East Coastincluding Carnegie Hall, Lincoln Center, Brooklyn Academyof Music, and the Bang on A Can Marathons, GGT is a mu-sical innovator focusing on new works by both Balinese andAmerican composers. GGT owns two sets of instruments.The first set was somewhat hard to blend to Western tonal-ities so a second set was commissioned from Bali with adifferent tuning more suitable for projects with Western in-struments. Tunning is not just a problem for GGT. DewaKetut Alit, one of the foremost composers in Bali, has alsoturned to working with multiple gamelans for a larger pitchrange within a single composition.

Tuning is not the only limitation gamelan faces. The en-

semble itself is large and very heavy. The instruments aremetalaphones, including large gongs, brass or bronze potsand gangsa with 1/2 inch thick brass/bronze keys and solidheavy frames. Transporting the gamelan to a performanceis a significant task on its own. With the mundane issuesof tuning and transport continually complicating commis-sions and performance, through the generous support ofAlex Rigopulos and Sachi Sato, GGT’s Gamelan Elektrikawas born: a more compact electronic version of the origi-nal instruments. Since the new instruments provide MIDI,Elektrika simultaneously gave access to new sounds and newtunings with as close to the original interface as possible.Another benefit is that MIDI is easily transcribable, prov-ing a valuable tool to any Balinese ethnomusicologist doc-umenting the aural tradition.

Gamelan Elektrika is not just about the instruments, butas gamelan should be, it is about the ensemble. Elektrikainvolves at least 11 performers playing often highly detailedinterlocking parts on silent MIDI instruments. Any seriousmusician knows how important audible feedback from theirinstrument is, yet Elektrika is an essentially silent orchestra.MIDI signals are routed to a single brain that has completecontrol over the player’s sound. We believe this is the firstsignificant large ensemble of this form.

2. THE GAMELAN INSTRUMENTSGamelan Elektrika is a subset of a gong kebyar ensemble.Gong kebyar is presently the most popular form of gamelanwithin Bali and is usually the focus for the most ambitiouscompositions.

A full Gong Kebyar can have 24 or more instrumentstuned to a pentatonic scale termed pelog. There are four in-struments that are almost exclusively percussion: the cengceng playing rythmic ornamentation, the beat-keaping kem-pli, and a pair of hand drums called kendang. Four largegongs punctuate phrase structure. A single stringed bowedinstrument, the rebab, and the suling, a flute, provide melodicornamentation. Along with the gongs, the instruments webuilt were the main melodic instruments of the ensemble.These main melodic instruments include the reong, a setof kettle pots, and both the pokok and the gangsa whichare similar keyed metal xylophones hit with mallets calledpangguls [10].

2.1 The PokokThe pokok are the melodic core played with rubber tippedwooden pangguls.

1) Jegogans- This pair is the lowest pitched set besidethe gongs and covers the 5 tone pentatonic octave. It gen-erally outlines key melody notes.

2) Jublags- The next pair up in range with slightly fasternotes and playing a more complete subset of the melody.The jublags have 5 or 7 keys.

3) Penyacah- A pair of 7 keyed instruments above thejublags. These generally play along with the primary ugalmelody.

2.2 The GangsaThe gangsa provide melodic elaboration and are played withhard tipped wooden pangguls.

4) Pemade- Two pairs of two octave 10 keyed instru-ment that provide the mid-range.

5) Kantils- The highest instruments in the gamelan, har-monizing with the pemade. There are two pairs of these

6) Ugal- Also spanning two octaves with 10 keys, it is theonly unpaired gangsa, generally linking with the kendang tolead the group. It plays the primary melody.

2.3 The ReongAlso spelled reyong, it plays melodic and rhythmic elabora-tion and is played with wooden sticks wrapped in string.

7) The Reong- Consists of 12 tuned kettle pots span-ning just over two octaves. These can all sit on one frameor be split between two. Considered one instrument, it isplayed by 4 people with the higher octave usually doublingthe lower. It is played similarly to bell ringing where anindividual is responsible for only specific pitches within themelody.

2.4 Ensemble PlayTwo major structural components of the music style are ke-byars- very fluid unmetered and variable interruptions (lit-erally to burst open) and kotekans-tight interlocking sec-tions where the melody is formed by the combination oftwo separate parts [4]. The gangsa and reong are the pri-mary kotekan instruments. For kotekan, players are pairedrather than instruments with half the gangsa (excludingugal) playing polos and half playing sangsih. Althoughthe interlock is rarely as straight forward as single note-to-note on-beat, off-beat interlock, polos primarily centersaround the beats with sangsih filling in the off-beat. Out-side kotekans, sangsih usually plays the melody in a rangeabove the polos. The reong often plays in kotekan withitself or plays unison rhythmic punctuations matching therhythm section [10].

3. RELATED WORKGamelan has recieved little engineering attention. AaronTaylor Kuffner, and Eric Singer, with LEMUR built theGamelatron, a robotic gamelan orchestra [2]. The Game-latron is a traditional set of instruments played roboticallyrather than a gamelan interface. Alternatively, Ajay Kapurhas looked at custom percussion controllers for traditionalinstruments with the EDholak and ETabla [6]. These areIndian instruments but involve similar approaches appliedtowards different ends.

Meanwhile, electronic MIDI interfaces replicating tradi-tional instruments are hardly a new thing. The first MIDIinterfaces were keyboards produced in 1983 by Roland andSequential Circuits. Originally intended as mere controllers,they were a clear mimic of the piano and quickly evolvedto fully replicate the it’s full range of interaction. 1984 sawRoland release the G707 a MIDI guitar controller followedby a MIDI only drum pad, the PAD8 ’Octapad’, in 1985 [8].The flexibility of MIDI means it has been found commonlyin new instrument interfaces ever since.

Gong Kebyar instruments are closest to xylophones andvibraphones in performance style although the dampeningtechniques of both the gangsa and the reong are unique.The sustained ring of the natural instruments and the play-ing technique developed around it means damping is muchmore integral to the instruments. Alternate Mode’s mal-letKat is the closest MIDI xylophone to fit the capabilitiesof gamelan. It uses FSRs (force sensitive resistors) to de-tect note onset and damping. It is also compatible with anymallet, matching a design goal to retain traditional playingfeel including real pangguls [1]. Wernick uses piezos in itsXyloSynth and is not mallet specific, but damping is basedon time release [5]. Don Buchla’s Marimba Lumina uses avery different approach based on radio frequency technol-ogy which enables capture of more playing style but requiresspecial mallets [7]. None of these instruments were designedwith similar dampening techniques in mind and hence, noneof them were sufficient for Elektrika.

4. ELECTRONIC GAMELAN DESIGNAlthough Elektrika is intended for long term use, initialdesign and construction was for the premiere of ChristineSouthworth’s ”Super Collider” with Kronos Quartet at theLincoln Center Aug 13, 2010. Part of Kronos’s commis-sion of the work was that it would be performed with elec-tronic gamelan and, to improve touring viability, it shouldbe a smaller ensemble. Hence rather than the full 24 in-struments, the ensemble was reduced to 13 instruments: 4gangsa, 2 pokok, 4 gongs, and a traditional rhythm sectionbut with only one kendang.

Traditionally the gangsa and pokok parts are doubled.The instruments are paired and slightly out of tune witheach other creating Balinese music’s shimmering quality.Since the instruments are sampled, the idea is that oneplayer can now trigger both pitches. This let us reducethe metalaphones to the minimum players.

The gangsas remain split between pemade and kantil witha polos and sangsih player for each section while the pokokis reduced to one jublag and one jegogan. Penyacah is oftenoptional in traditional Gong Kebyar and was left out. Thereis also no ugal. There is no substitute for a full reong : twoframes house 12 synthetic pots. The gongs, previously themost massive and heavy part of the ensemble, have beenmoved onto one significantly more portable frame.

The rhythm instruments have remained the traditionalacoustic versions. There were never any plans to build anew hand drum interface for the kendang as commercialelectronic drum systems are readily available. After test-ing a couple, they were not to taste, so we stayed with theacoustic originals. There were plans to build a kempli and,as the instrument is similar to a reong pot, it is not a sig-nificant technical challenge. However the kempli keeps thebeat and is what players lock onto. It is preferential forits sound to remain centered within the ensemble and whileslight latency or problems with another instrument can bedealt with, latency or missed notes on the kempli could bedisastrous. A guaranteed anchor becomes especially impor-tant as the other instruments do not actually make noise.The ceng ceng, although desired, has yet to be built dueto time considerations. Being a small ancillary instrumentrequiring a unique engineering solution, leaving it acousticfor ”Super Collider” and augmenting it with a drum pad forthe few synthetic sections was deemed acceptable.

There were a few dominant themes in the design goals forthe instruments. As previously mentioned, the instrumentsshould be lighter and more compact for travel. They shouldalso retain as much of their original feel and performancetechnique as possible. Being able to use the normal mal-lets was preferable but not required. Meanwhile, the over-all ensemble performance included the plan for instrumentsthat could change samples and effects on the fly during per-formance but has to remain intuitive and understandableenough that the performers can still meet the demands ofcoordinating complex parts with the other performers.

4.1 Gangsa and Pokok DesignFocusing on the gangsa requires further discussion of play-ing technique. Proper playing of the gangsa (and pokok)involves striking the key with a panggul in the right handwhile dampening the previous note by grabbing the end ofthat key with the left hand. This creates the effect of onehand trailing the other. Musical texture can be varied bychanging how long a struck note is allowed to ring and useof a ”closed” hit meaning the key is damped while struck.

The gangsa have gone through two major design itera-tions. As fingers are used for damping, the initial designidea used in the first performance was to use a piezo to

detect strike and strike velocity and a touch capacitive sen-sor to detect dampening. First prototypes were made usingacrylic but transitioned to cast urethane rubber keys. Thiswas done as the rubber acts as a good acoustic dampenerwhen hit by hard wood mallets and also has sufficient springfor good recoil. Casting also allowed the electronic keys tophysically mimic the originals.

We used Vytaflex 20 for it’s bounce and color, backing itwith a 1/4 inch acrylic sheet. A large 1 inch piezo disc wascentered on each piece of acrylic before casting and a copperplate added at one end. The piezo was sandwiched betweenthe acrylic and the urethane while the copper capacitiveplate resided underneath exposed to touch.

Figure 2: Pemade with rubber tipped panggul. TwoFSRs between acrylic detect central strike and edgedamping.

An Arduino Mega, able to support the analog inputs fromupto 10 keys, was used to process the signals generated onthe gangsa. Aside from light conditioning, the piezo signalsfrom each key went directly to the chip analog inputs wherethey are polled. The capacitive signals were processed firstusing a single Atmel QT 1103 capacitive touch sensor whichsubsequently sent the now digital results to the Arduino.

Integrating the size of the piezo strike provides velocity.Gangsa and pokok are played one note at a time which alsomade cross-talk largely a non-issue. The strongest fastestsignal is always the target signal. The capacitive sensingdesign was more challenging as the pad sizes were quitelarge (starting from 1 inch x1 inch) and had to be tuned.When too sensitive, passing the hand near the sensor, as is acommon in performance, triggered unintentional damping.

During construction and testing of the first gangsa design,we found that inconsistency in the casting thickness andpiezo placing and adhesion, meant that velocity responsewas insufficently uniform and non-intuitive. Working withpiezo discs, the adhesive and mounting significantly im-pacts the quality of signal recieved so slight differences leadto comparative inconsistency. For an instrument made byhand, sufficient consistency is hard to achieve. Adding tothis, the urethane damps too effectively. The physical hitdoes not propagate adequately throughout the whole keymeaning that a hit far from the piezo registers more weaklythan a hit directly above the piezo even though the physi-cal force used was the same. A simple calibration test wasdevised using a ping pong ball dropped down a paper towelroll. Although detecting the strike was reliable and repeat-able, the velocity sensitivity was not and deemed insufficientfor use in performance.

These issues were addressed with a significant redesignafter the first performance. To fix issues with velocity con-sistency, each key on a gangsa now uses an FSR sandwiched

between acrylic with a second FSR to detect dampeningfrom a hand squeezing. Thin foam spaces the acrylic ap-propriately to the sensor size. FSRs can be slow to de-compress and return to original state, an issue handled byuse of a moving baseline. After considering playing styles,it was decided that the damping rate of the real instru-ment directly corresponds to the pressure with which itis squeezed and damping would be more appropriately de-tected through pressure. Conveniently, switching away fromcapacitive sensing resulted in more reliable damping, al-though frequent calibration was required while the new in-struments settled. With the struck surface now hard acrylic,accoustic damping of the strike is achieved by attaching ure-thane to the panggul tip. Although a slight divergence fromthe intended goal to use unmodified pangguls, it is a minormodification not significantly changing feel.

The pokok, being similar in playing technique to the gangsa,have used the same designs adapted for correct scale.

4.2 Reong DesignThe 12 pots of a real reong rest on strings providing bounceand enabling resonance. It has four players who each havetwo string wrapped pangguls and play single note melodiesor chords. There are two primary styles of hit, the byongand the chuck. The byong is produced by striking the bossor nipple of the pot with the string wrapped part of thepanggul and produces a clear pitched tone while the chuckis produced by hitting the flat part of the pot below theboss with the panggul ’s hard wooden tip. The chuck is lesstonal and more percussive.

Like the gangsa, the reong pots ring significantly andare damped for musical clarity and texture. Damping isachieved by direct pressure applied using the panggul witha technique of double hitting. The first strike is allowedto ring while the second, quieter damping strike sustainsenough pressure to mute the original. In practice this isdone very quickly and is hard to master. The reong alsofeatures a closed hit which is one that is never allowed toring. Both byongs and chucks can be damped this way al-though the decay from a chuck is fast enough that dampingis not as significant a concern.

The physical design of a reong pot is an acrylic mimic.A solid acrylic column topped with soft rounded Vytaflexurethane rubber is used for the boss and is mounted freelyin a removable acrylic pot. A special rubber chuck pad sitsin the pot edge. The byong column is kept in place by abase it slots into. Felt is placed between the column andthe pot to eliminate contact sounds and ensure proper fit.Byong strikes are measured using a piezo film placed

within the base the column slots into. This enables thepiezo to stay in a stable location. An FSR is co-locatedwhich is used to detect pressure and damping. The piezoresponse occurs faster than the FSR response and is eas-ily tuned to capture a full range of velocities through sig-nal integration. Using the FSR alone was not done as thecolumn is tightly centered by the felt and the rest posi-tion and pressure from the byong column are not alwaysconsistent. Original tests also showed issues with dynamicrange and the slow response of the FSR increased latency.The combination of the two has also proven very handy foridentifying cross-talk. The byong sensors are sandwichedwith foam and felt to provide some isolation from vibrationtransmitted through the frame and the column. Lastly, af-ter the debut performance, it was found that the additionof a light weight disc spring isolates the column from thesensors, dramatically reducing cross-talk signals for muchimproved low-level sensitivity.

The chucks were originally built with a piezo film beneath

a urethane pad combined with two FSRs in the pots rubberlegs. The electronics will actually support four FSRs whichcould be used for position sensing but only two so far havebeen used. These sense pressure on the pot indicating thepot is damped.

During construction it turned out that the sensors arefairly delicate and would break easily placed in the potlegs. Additionally, as with the gangsa, the urethane didnot transmit the strike evenly so that the chuck velocitywas strongly linked with where and how it was hit. Afterthe debut performance, the piezo was removed and the twoFSRs were moved to directly beneath the pad. Being moredirectly pressure sensitive, the FSRs remain largely cross-talk impervious. Using two FSRs enabled coverage for thefull pad area and securing them under the pad is a less riskylocation for breakage.

Figure 3: One half of the reong holding six pots.The center is a free-standing rod with piezo filmsand FSRs placed underneath used to implement by-ongs. The small pads on the right are the chucks.

With up to seven inputs per pot, each reong pot has itsown sensing engine. The piezo and FSR signals are runthrough operational amplifiers for gain control and maxi-mum dynamic range before being analyzed using an AtmelMega 88. Although initially interrupt driven, polling turnedout easier and sufficiently effective. The latency for sendingis under 7 ms with a 70 ms debounce hold after which itbegins checking for dampening.

Unlike with the gangsa where cross-talk is easily ignoredby selecting the peak signal, up to four of the six pots ona reong half can be played simultaneously. Additionally, areong pot is uninformed of a neighbor’s signaling and thesensors are affixed to the frame recieving signal propaga-tion through it. The paired behavior of the FSR and thepiezo enable the differentiation between cross-talk and a hit.With both the byong and the chuck in the case of cross-talk,the piezo response is timed significantly different from theFSR response. The column and the pot both being freestanding, the FSR does suffer from cross-talk. With thebyong column, the FSR signal is caused more from the col-umn landing after a cross-talk induced disturbance so thatit significantly lags the piezo response to the initial vibra-tions. The FSR signal also often rises before dropping asthe column bounces.

Although each pot has its own MIDI out, for efficientcabling, each half of the reong also uses a Parallax Propeller

to combine the MIDI streams on a frame for a single out.The Propeller, with eight parallel cores, turned out to beperfect for this task as a core could be devoted to trackingeach of the six MIDI inputs and queing input messages in astack to be sent out through an output core. This alleviatedany concerns for collisions and means if the maximum offour pots are hit simultaneously, it adds a maximum of only5 ms latency and guarantees no missed messages. The MIDIcombining board also acts as a power distribution source forthe other boards.

Figure 4: Gamelan Elektrika gongs being performedby Mark Stewart and Jacques Weissgerber. Rearmounted piezos discs are used to detect the strikewhile the gold discs in the center provide damp-ening through capacitive sensing. Photo by KevinYatarola

4.3 Gong DesignAfter toying with a couple of novel designs it was decidedto use the same sensing arrangement as the gangsas for thegongs. Each of the four gongs have a piezo attached to alarge acrylic disk to detect when it has been hit. Damping(not musically required but immensely useful as gongs haveextremely long resonance) is done by mounting a large cop-per vinyl circle at the center. This is also visually suggestiveof a gong. Again, the electronics are simply a reduced ver-sion of the original gangsas. As the strike surface is acrylic,the gongs do not suffer the same strike propagation issues.The inital design and construction proved itself well in thefirst performance and has only needed minor maintenance.

Structurally, the size and weight of the gongs have beendramatically reduced. Four large stands have been com-bined into one that holds four free swinging acrylic disks.Their sizes range from 9 to 12 inches in diameter, function-ally matched to the real gongs according to their size.

4.4 The BrainAccording to performance tradition where a musician is infull control of his sound, each player would be able to mon-itor and select sound banks locally. However in our case,individual control of a sound bank would be both a physicaland mental challenge as the hands are fully occupied duringa sitting performance. It seems appropriately Balinese toconsolidate sample bank control in a central brain. Also,individual monitoring though highly advantageous, ends upeither a cabling and mixing nightmare due to scale. A localsynthesizer module is presently prohibitively expensive.

The result was a risky but necessary decision to generateall sound through one computer. The brain is a Macbookrunning Ableton which a musician uses to select samplebanks in real-time. MIDI input boxes take 10 different in-strument inputs and pass the MIDI note information on toAbleton. This has a disconcerting effect on a musician dueto the lack of direct feedback from the instrument, replacedwith the need to pick ”your” sound out of a full mix. Addedto this, the sample bank may change without the musician’sinput. Performance in this environment requires trust in theinstrument behavior, low latency, and a different level ofphysical comfort than normal with a piece. Technical chal-lenges aside, it was not certain from a musical perspectivewhether this would be a feasible performance environment.

5. RESULTSSouthworth’s piece ”Super Collider” successfully debuted asplanned to an audience of over 5000 on Aug 13, 2010 at theLincoln Center performed by Kronos Quartet and GamelanGalak Tika using Elektrika. Apart from some issues eventu-ally traced to electrical interference in cable runs, the finalinstruments worked largely as intended though they lackedvelocity sensitivity. The decision to drop velocity was asmuch due to musicians inexperience with the instrumentsas technical challenges.

Kronos Quartet rejoined for a second performance onApril 15, 2011, at MIT’s Kresge auditorium to a sold outcrowd, using the second version of the gangsas. This timethere were no problems from the instruments. Improvedinstrument sensitivity and reliability plus rehearsal timeenabled the return of instrument dynamics. Both perfor-mances were a success. The Boston Globe called the second”coolly exhilarating” [3]. [should I cut the Globe reference?]

Rehearsals smooth some of the disconcerting effects ofsample bank changes and transpositions not triggered bythe musician. The lack of local monitoring has displayeditself to be a challenge but not insurmountable. An exampleof the trouble it can cause is there are times the pemadepolos part is in unison with the kantil polos. If one playeris slightly ahead or off, it becomes very difficult to knowwhich player is actually the one ahead as there is no soundidentification and correcting by trying to slow back a bitcould just make the problem worse.

The ease of transistion from learning on the original in-struments proves Elektrika’s success at being interchange-able with the real instruments but dynamics remain a chal-lenge. A musician learns an instrument through feedback-hitting this hard produces this level of sound. For Elektria,sound systems and outside sources also effect volume, so adefinite understanding is hard to come by especially with-out the chance to learn in a solo environment. Due to setup and rehearsal constraints this is yet to be mastered.

The redesigns for the second performance have yieldedrobust and satisfactory instruments. The instruments playconsistently and sufficiently similarly to the originals. First,the gongs never needed much revision. The move to FSRsfor the gangsa provides more expression at the cost of slightlatency due to FSRs slow response time. Interestingly, thelatency is small enough that musicians cope very quicklywith it once aural feedback is available. Each time a newsound setup is used with different monitoring paths, the au-dible latency changes slightly regardless of the instruments.This requires learning new timing. At each new setup, themelody starts with a swing as interlocked syncopations areslightly off. However the section adapts and evens out afterjust a few minutes of sectional practice.

The addition of the disc spring after the first performance

Figure 5: Gamelan Elektrika played by Gamelan Galak Tika during its premiere with Kronos Quartet atthe Lincoln Center. The reongs and two pokok can be seen on the far side with the four gangsa and gongson the left. The rear center features the accoustic percussion section, the computer ”brain”, and traditionalgongs which Kronos Quartet played as part of the performance. Photo by Kevin Yatarola

largely eliminated sensitivity limitations for the reong by-ongs. It is responsive and reliable. Now there is just theaccoustical issue whether the damped sound can be achievedusing the same sample as the open hit. The move to twoFSRs for the chuck works and has resulted in fewer tornsensors than the first design, but is otherwise not a majorimprovement.

6. FUTURE WORKWith the first two performances complete, Gamelan Elek-trika is next bound for the Bang On A Can Summer Fes-tival. It will be used in the composition course to teachgamelan and available for use by the students. Terry Riley,previously reluctant to write for the group, has also beencommissioned to write a piece for performance in the springof 2012.

The second rebuild of the gangsas has settled well at thispoint and is now plug-and-play with no forseeable signifi-cant chances. The reong is due to move to a new largerframe that can effectively protect the electronics, presentlyexposed underneath. The byong has proven reliable, sensi-tive, and expressive and will merely require being rebuilt inthe new frame. Switching to just FSRs to sense chucks forthe second performance has resulted in a confusing mixtureof latencies as the piezo driven byong is much more instan-taneously responsive. During the rebuild, the piezo will bere-incorporated for consistent response time. To mitigatethe directionality of force applied to the urethane, the padwill also be given a firm base so pressure applied anywhereon the pad can be equally detected.

Long term technical term goals are to provide an in-earmonitor capability at each instrument, or instrument pair,enabling the musician to easily hear and distinguish whatthey are playing. There are also plans to finish the as yetundesigned electronic ceng ceng and the option of the elec-tronic kempli in order to complete all the electronic instru-ments originally envisioned.

7. CONCLUSIONS

The Gamelan Elektrika instruments work. They achieveboth primary design goals- a significantly reduced physicalsize and weight and a similar feel to the original. ThroughMIDI we have been able to meet the musical goals of vari-able tunings, wider sound palette, and easier transcription,The initial success even on immature instruments has beenbrilliant, and gamelan can now participate in the electronicage of music that other instruments entered years ago. Forperformers and musicians in the genre it is a freeing andexciting development.

8. ACKNOWLEDGMENTSTremendous thanks to Alex Rigopulos and Sachi Sato fortheir funding, support, and guidance without which Elek-trika would be just an idea. Thanks also to Quentin Kelleyfor building us beautiful frames, Galak Tika director EvanZiporyn, Jaques Weissgerber, Katie Puckett, Julie Strand,Bill Tremblay, Noah Feehan and Steph Bou and the rest ofthe gamelan for their help, support, and patience. Thanksto Kronos Quartet for such a brilliant debut and lastlythanks for the support of Dr. Joe Paradiso, ResponsiveEnvironments and the MIT Media Lab.

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