Advice for Jaw Harp Makers

Introduction

This article offers strategic guidance on what deserves attention when making a jaw harp. It concerns the intended result: what to strive for both in physical construction and in the more abstract experience of using the instrument. Manufacturing technique—which hand holds the hammer, which abrasive grit to use and so on—is a personal matter shaped by habit and available tools, and is not discussed here.

Gaps

The gaps between the reed and the decks must be minimal and perfectly even.

That is only one simple sentence, familiar today to almost every maker. In practice, however, attention becomes dispersed across countless details surrounding the process and across purely visual features of construction—too often the design of the frame. Yet the gaps are among the most important parts of a jaw harp. The only excuse for neglecting them is the real practical difficulty of achieving the required accuracy and the absence of one universal numerical specification. A gap of 0.5 mm may look very small, but only by the standards of a tram door.

a) Gap width affects maximum volume, the ease with which that volume is reached, and the breadth of the spectrum. Smaller gaps produce greater volume and a broader spectrum. Larger gaps produce a quieter, duller sound in which mostly low components remain. The requirement becomes less severe as the instrument's fundamental frequency falls: on a very low jaw harp, the difference between 20 and 100 micrometres may be modest, while on a high instrument it is enormous.

Beginning makers often say that narrow gaps are impossible because the jaw harp will clang. The answer is to learn to hold it accurately and to teach players to do the same; the result quickly becomes apparent.

b) Even gaps and parallel edges, together with the material and geometry, suppress isolated unwanted noises and determine overall musicality: whether the components of the timbre combine harmonically and speak at a balanced volume. This balance governs versatility. Almost any frightening noise can be fitted into a particular composition by a musician who knows exactly where it belongs, but that is a special case. To play music without changing instruments for every piece, the player needs reasonably even access to different notes—the harmonics. Physical evenness of the gaps is the first step.

Many contemporary jaw harps fall short here. The result is buzzing that swallows or masks individual harmonics and gives the entire timbre a mechanical colour. The easiest measuring instrument is the ear: if a separate buzz is present, some part has deviated.

Many more technical points follow, and the amount of text can scatter attention among them, so it is worth repeating: the gaps are fundamental. Until you can make them with almost inhuman precision, the rest of this article is secondary.

Reed material

The grade of steel and the way it is treated form the second major group of factors affecting every acoustic quality of the jaw harp. Development is complicated because material interacts with reed geometry and pitch. Steel that works beautifully in a long reed may fail completely in a short one. This makes universal recipes and simple answers to “which steel should I use?” impossible; the number of combinations tends towards infinity. Test as many options as possible and do not stop at the first success.

Reed geometry

The combination of length, width and thickness—and the way width and thickness change along the length—determines the balance of the timbre, the evenness of the harmonics and the instrument's musicality.

The working section. Among other things, volume depends on the speed at which a part of the reed passes the decks, and that speed is greatest at the free end. Near the attachment point the reed hardly moves. Maximum attention should therefore go to the final part of the gaps, which is also the part directly in front of the resonator, the player's mouth. There is little value in spending equal effort fitting the entire length when most of it contributes much less to the sound.

The bend and trigger. Beginning makers often treat the bent end merely as a hook to pull. This is a serious mistake. It has two functions: besides receiving the strike, it can influence the vibration of the working reed as strongly as the reed itself.

If the bent trigger is long and soft, it begins to oscillate independently after a strike and interferes with the working section. It introduces unrelated frequencies and can change an ideal, even spectrum into one with deep holes in one region and peaks in another. Length, mass and stiffness work just as they do in the main reed, shaping both the character and strength of this unwanted contribution. Since that contribution is not useful, reduce it as far as possible: make the bend shorter and stiffer.

Even a rigid end can oscillate on a thin, flexible main reed. Ideally the entire bending zone therefore needs greater stiffness. A straightforward way to achieve it is to vary the reed thickness from thinner at the root to thicker towards the trigger, then correct the rest of the geometry for the resulting stiffness. The chosen thickness curve also changes the balance of the harmonics and can suppress colourful but unmusical noises.

The second function is mechanical: making the strike comfortable and repeatable. No action matters more continuously to the player—without a strike there is no sound. A rigid trigger follows the same path every time. If it wobbles, one strike becomes stronger and the next weaker, reducing dynamic control and speed and creating simple physical discomfort. The trigger ring should follow a clean arc rather than drawing small zigzags around it. Once it does, dynamic control and precision of sound production increase dramatically.

Frame

The frame receives most of the attention in many jaw harps. It is honoured, polished and decorated, and in the minds of many players—and even makers—the word “jaw harp” refers primarily to the frame. Every year makers release new models that use the same reed while changing only its holder. The possibilities for materials, colour, shape, ornament, added pieces, stands and cases are limitless.

Acoustically, however, the instrument is largely the reed plus two abstract lines: the inner edges of the decks. Visual exploration is interesting and entirely legitimate after the playing qualities have been brought close to perfection. At present very few makers direct most of their effort towards that goal.

When the jaw harp is considered as a musical instrument, the frame has one overriding practical function: it must be comfortable to hold. Concentrate on ergonomics first and decorative invention second. An instrument assumes regular, prolonged use, so ergonomics matters no less than sound. An ornate frame with angular curls may deserve a place in an art exhibition or collection, but if it prevents relaxed holding—or needs a special trolley for transport—its purpose deserves reconsideration.

Testing

Always test the sound under different acoustic conditions. Perception changes strongly with the surroundings; every room exposes a different part of the spectrum. Even within one room, play close to a flat reflective surface—perhaps 20 cm from a window or monitor—then in the centre, in a soft furnished corner and in a tiled bathroom. It is also highly desirable to repeat the test outdoors, where reflected sound is minimal.

Add the full dynamic range from the weakest to the strongest safe strike, and vary both the speed and direction of striking.

Finally, test the musical sounds themselves. Learn to isolate several harmonics at different pitches with both an open and a closed throat. This reveals major irregularities in the timbre very clearly.