The ondes Martenot is perhaps best known for its unique control mechanisms: the ring and ribbon, the vibrato keyboard, the volume-controlling lozenge. But equally important to the instrument’s classic sound are its loudspeakers, called “diffuseurs”. Over the decades that he built his instrument, Maurice Martenot repeatedly invented and produced totally new types of loudspeakers. The four main types of diffuseur are the Principal (standard loudspeaker), Résonance (springs suspended in front of speaker), Metallique (gong used as speaker cone), and Palme (suspended strings allow for sympathetic resonances). This article will discuss how to reproduce the sounds of the Palme, and briefly also the Résonance.
The Palme was first produced in 1950, and was even the subject of a talk at the Académie des Sciences in July of that year. The diffsuer gets its name from its distinctive shape, which is similar to a palm leaf. The leaf-shaped box is actually a resonant space, much like the body of an acoustic guitar, over which strings are suspended. It features a total of 24 strings, 12 on each side of the diffuseur. Each set of twelve is generally tuned to a full chromatic scale, ascending by semitone from left to right, though some pieces may call for alternate tunings (such as those by Tristan Murail). The back strings may be tuned an octave above the front ones. With Radiohead, Jonny Greenwood has not only used his Palme diffuseur with his ondes Martenot, but also to process Thom Yorke’s vocals on You And Whose Army.
The first question to ask when attempting to reproduce the Palme is this: how much do you care for historical accuracy?
In this photo of Takahashi Harada and Haruomi Hanabusi performing together in Tokyo, one can see Harada’s Palme diffuseur resting on top the cabinet containing his Principal and Résonance diffuseurs (style.nikkei.com).
The Résonance Diffuseur
Although some performers use both side-by-side, Martenot essentially replaced the Palme with the Résonance diffuseur in the 1980s. The Résonance uses a set of seven brass springs stretched in front of a speaker to create resonance and reverberation. Unlike a spring reverb, in which the instrument’s signal is electrically passed through the springs, the springs of the Résonance are excited mechanically. The brass springs are in fact physically connected directly to the voice coil of the Résonance’s loudspeaker. Martenot produced both larger cabinets containing both the Principal and Résonance diffuseurs, and also smaller cabinets containing stand-alone Résonance diffuseurs.
If you decide to forgo the reproducing the Palme and choose to emulate the Résonance instead, you wouldn’t be alone. Dierstein’s new ondes Musicales offers only Résonance (in its double cabinet with the Principal) instead of the Palme. Since obtaining the first ondes Musicales Dierstein in 2011, Jonny Greenwood has generally used the Résonance in place of his more of his more delicate, temperamental, and irreplaceable Palme.
A true Résonance wouldn’t be easy to replicate, but it could be easier to reproduce than the Palme. Doing so would bypass the need to create any sort of resonance chamber, and would be easier to maintain during a performance since one wouldn’t need to keep any strings in tune (since the resonant sound of the Palme is a product of its strings, if they’re out of tune the the resonances will be too). Once you’ve created a cabinet to hold your speaker and suspend your springs, the main challenge would likely be to physically connect them without dampening resonances or damaging the speaker. This may be why no true replicas have yet been made (even Dierstein’s Résonance works differently). Such a replica would not have the haunting sound of the Palme, of course, but if done well it would produce a particularly rare and rich resonance.
And if you only want a vaguely similar sound, you could find or build a highly-adjustable spring reverb, or even an adjustable digital one, and tweak it until is sounds close enough.
In this photo of Cynthia Millar performing Messiaen’s ‘Turangalîla Symphony’ at Barbican Hall on May 24, 2017, one can see her standalone Résonance diffuseur positioned in front of the piano (classicalsource).
A photo of the inside of a Résonance diffuseur (radiomuseum.org)
The Palme Diffuseur
While the most distinctive physical characteristic of the Palme is its shape, what makes it unique sonically are tuned strings that are suspended on either side of the sound box. The strings are usually tuned to the notes of a chromatic scale, since this provides an equal resonance for each note of the scale, but one could tune them alternately to create resonances on only certain notes, or even on particular microtones. Strings are provoked into excitation by a sound-exciter (the transducer part of a speaker: its voice coil, pole piece, and magnet) located in the “stand” under the sound box. The exciter is connected directly to a bridge, across which the strings are strung, meaning that the strings are excited directly by it. This provides a more immediate transfer of energy, and therefore a stronger sound, than would be the case with sympathetic resonance (as is the case for the extra strings on instruments like the Viola d'amore or Sarangi).
Since all twenty-four of the strings are connected to the bridge at all times, playing through the Palme results in vibration not only of the string tuned to the fundamental frequency of a given note, but also of the strings tuned to the overtones of that note. This principal is really essential to the Palme’s sound. It means that the Palme doesn’t simply provide the sound of a vibrating string for a each particular note. The softer vibrations of the non-fundamental strings are determined by the balance of overtones in the waveform being used, and contribute significantly to the haunting “aura” of the Palme.
Lastly, the “leaf” sound box of the diffuseur provides a resonant space for the sounds produced by the strings, much like the body of an acoustic guitar or violin. The acoustic amplification of the chamber provides a stronger tone with a longer resonance, and as such it’s very important to the Palme’s overall sound.
If you wanted a really simple, makeshift Palme, you could buy a really cheap sound-exciter (such as this) and connect it directly to the bridge of a stringed instrument One could try sticking a speaker inside of an acoustic guitar, but the sound would be inaccurate to the original since it wouldn’t excite the strings directly. A twelve-string acoustic guitar might be a good instrument to modify into a Palme, since one could tune the strings to the entire chromatic scale, although I would be careful of the tensions. You should probably tune the strings down in pitch from standard, rather than tuning any to higher pitches, lest you risk snapping the neck. Attaching the sound-exciter to the underside of the guitar’s soundboard – ideally directly beneath the bridge – might create a pleasing resonant sound. It would also be worth experimenting with different types of strings: apparently the original used mandolin strings.
Most commercially available sound-exciters are too weak to be useful for a Palme, a few companies produce good quality sound-exciters, such as Monacor or Dayton Audio.
For a more authentic Palme, you’d need to build or commission a cabinet. The contribution of the exact shape of the sound box to the Palme’s sound is hard to determine, so a lot of experimentation might be necessary. The base is also fairly important, as it is where the bridge/tailpiece and sound-exciter are located. Given the peculiarities of the Palme, if you were to have a cabinet constructed then a luthier would probably be a better option than a carpenter.
The base of the cabinet suspends the body above the bridge/tailpiece, so that the sound-hole is near the center of the span of the strings. This is a major difference compared to most string instruments, on which the bridge is connected to or rests upon the sound-board and can influence it directly, but you may or may not deem that detail necessary for your copy. If you decide to replicate the original bridge, you’ll have to choose between two versions: Martenot’s earlier bridge is just a single square of metal, shaped to hold the string-ends and direct the strings upwards, while Martenot’s later bridge has a separate bridge and stoptail. Jonny Greenwood’s Palme is of the latter type, which seems to be standard for later (70s?) Palmes.
Top: the early-style bridge. Bottom: the late-style bridge (forum.anafrog.com).
There are also two different methods of suspending the strings, or “tuners.” Earlier models have the tuners based on the top of the instrument, while later models have them held through the soundboard(s). This change was made earlier than that from one bridge to the other, and so models exist with the earlier bridge, but the later string-suspension position.
The Palme is strung with mandolin strings, but one could experiment with a variety of metal strings for a copy. If choosing guitar strings, one might one might be able to use a twelve-string guitar’s bridge and tuners rather than building custom parts. A 12-string Tune-o-matic style setup could work, as could something closer to what is found on Arch-top guitars.
Top: the early-style tuners. Bottom: the late-style tuners (forum.anafrog.com).
A Palme with the earlier bridge-type, but the later tuners (radiomuseum.org).
Lastly, in order to determine how best to suspend the strings, one must also determine which sound-exciter to use and how to mount it in the cabinet. One might be find the better quality commercially available options suitable (like Monacor or Dayton Audio), but it necessary to build you own. Martenot seems to have built his own sound-exciters for the purpose, and according to Naoyuki Omo they’re specialized to move back and forth more forcefully than a normal speaker coil. It might be best to design a cabinet which could fit multiple types of exciter, since it will hard to try different ones otherwise. Overall, it might be best to build your Palme in a modular style, such that each part can be adjusted or replaced without too much difficulty.
An image of the an original Martenot sound-exciter/resonator, from the Metallique diffuseur (radiomuseum.org).
Summary
It seems that the fundamentals of a Palme are these:
Cabinet with acoustic amplifying/resonant space.
Strings suspended in front of the sound-hole of that space.
Bridge on which the strings rest is directly connected to a sound-exciter.
Sound-exciter and bridge kept in a “base,” which holds up the amplifying space but keeps the exciter and bridge separate.
If anyone ever does build a copy, I’d be happy to see and hear it. Best of luck!
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Existing Copies
Just as the limited availability of authentic ondes Martenot has provoked many copies into existence, there are already a few copies of the Palme out there.
Claude-Samuel Levine’s Palme is similar to later Palme diffuseurs, but shows some notable differences from other Palmes, specifically in the “bridge.”
The Naoyuki Omo of the Japanese company Asaden (who also produces the Ondomo) has also created a Palme copy. It is quite different from either of the originals in how the strings are suspended, but the fundamental principles are the same (resonating strings suspended in front of a sound chamber). Both the sound-excited and the cabinet are custom-made. Apparently it is much easier to tune. It only features strings on the front half of the diffuseur. You can listen to it here.
Last, a French musician seems to have build their own ondes Musicales and several diffuseurs. Their Palme diffuseur seems to be a modification of a large, rectangular zither.
