Donuts – Chapter 20 – Part 2

by Christopher Millard | Jan 4, 2023

Brains and Membranes

Bassoon Reed Making by Christopher Millard

Chapter 20 – DONUTS – Part 2

Our Little Bassoonist is trying to make sense of this language about geometry and radial transitions. To see how her reeds evolve from tube to tip, she imagines sawing her reeds into numerous cross sections. She finds ever enlarging diameters as well as transitions from strongly convex at the back to flexibly concave towards the front.

What truly grabs her attention is the increasing complexity in the curvature of her blades. As the radius expands there is a gradual shift from convex to concave resting states!! This is a feature of all bassoon reed topologies. Whether big or small, wide or narrow, almost every reed has a region where expanding curvature interacts with ‘profiler induced’ softer cane to produce inward flexing towards the wings.

Whether or not you see obvious concavity at the aperture will largely depend on your reed’s width and profile – and ultimately your embouchure and air preferences. Our Little Bassoonist likes a reasonably wide shape, so her cross sections start to show a transition from convex to concave around the middle of her blades. More narrow shapes may not necessarily show concave collapse in the wings in their resting state. But even in a narrow reed, the wider portions of that reed must still flex inwards as the membranes respond to air flow. Inward flexing in the wings and sides is an inevitable outcome of the Bernoulli effect, where accelerating air flow reduces pressure on the inside surface of the blades. This induces closure of the blades, enhanced by the widening, arrowhead shape of the bassoon reed combined with typically softer profiles towards the wings. .

Coffee and Donuts: to the drawing board!

In Chapter 10 of Brains and Membranes, we shrank LB down into a tiny, time-dilated observer. She was able to witness the messy and non-linear oscillations of reed membranes. Nothing was very smooth! No sine waves, but instead lots of flapping and asymmetrical contortions. It’s chaotic. And yet, most bassoonists are persuaded that symmetrically balanced profiles and trims lead to better reeds. Is this a paradox? Do geometrically beautiful membranes – with smooth radial transitions – offer the best mechanism for harnessing the acoustical chaos and delivering better reeds?

This is a contentious subject for reed makers! Everyone has experienced reeds that appear unbalanced and irregular – yet somehow perform well. But, notwithstanding the fact that visually irregular reeds are occasionally fine, I remain convinced that highly symmetric reeds significantly improve one’s odds of successful outcomes.

Our Little Bassoonist [who has been forced to participate in these 20 arcane chapters about reed acoustics…] is coming to a simpler interpretation of all this: visualizing radial/topological transitions is just a search for functional balance. Many bassoonists associate ‘balance’ purely with dial indicator measurements, leading to matched profile thickness in all four quadrants. But functional balance is only revealed after the reed is built, when all the growth memories meet the newly imposed tube structures, revealing shape variability as the cane asserts itself in its new form.

Careful measurements with a dial indicator can be useful, but the structural inconsistencies of Arundo donax will more often bring disappointment.

The word ‘balance’ gets thrown around so much it might be wise for reed makers to consider better definitions. I think the word can describe the organized integration of axial and radial forces within the finished reed.

Vector illustration of Yin and Yang symbol isolated on white background

We all learn reed making through trial and error; remove a little cane and see what happens. If it works, we repeat the same maneuver on a similar reed and hope for a successful outcome. Younger players correctly follow their teachers’ suggestions, and despite inevitable disasters everyone eventually develops some reliable skills. But it’s mostly empirical. I’m not sure that we think through what happens physically to the reed behaviour when we take a knife or file to a particular spot. For example, will removing cane increase or decrease the potential for flexibility in any given spot? Will the removal contribute to overall radial symmetry?

All the past chapters of this blog are leading to a more holistic view of the reed valve and its complex Yin/Yang behaviour. My advice is to always follow this underlying principle: pay attention to structural symmetry. Well-planned profiles will give your reeds the best opportunity to demonstrate compliance with the non-linear, non-sinusoidal and acoustically asymmetrical internal standing waves.

LB is so often frustrated. Though she takes particular care with both her profiling and her blank assembly, her finished reeds are often irregular and warped. Great care, good intent, but puzzling asymmetry. Why? Part of the answer may lie in improving her assembly techniques, paying attention to the distribution of cane as pliers and mandrel interact. Everyone has a slightly different solution to getting the best possible blank. But there remains an overlooked practice that I’ve seen time and again – it’s over-reliance on profiling machines to do most of the work.

Asymmetrical outcomes typically result from overly profiled cane.

Throughout this blog I’ve avoided giving specific advice on techniques and designs. But I’m going to bend that rule a bit and suggest a protocol that I think will improve outcomes for many players.

I think most young players expect profiles to deliver 95% of their expected final trims. Of course, why not? It’s logical to use machines to do the work!

The most obvious weakness of that strategy is when a piece of cane is too weak for a given profile. You all know what it’s like to have 10 pieces of GSP and discover half of them wind up to thin and soft. But I’m addressing a more fundamental problem: profiles are so often not thick enough to maintain smooth radial transitions. When profiles are too thin, the brutal process of folding, applying wires and molding cane to mandrel easily lead to structural irregularities. These include precipitous radial collapse in the back sides, sudden transitions at the border between convexity and concavity in the wings, or simple warping in the front of the blades where the profile is thin. These all create unintended internal radial memories, where the four quadrant behaviours are too irregular for most efficient interaction with the acoustical turmoil going on inside. And the outcome of these unintended geometry changes? Compromises in resistance, control, pitch and tone color.

I want to suggest a strategy which I have employed for decades in my own reed making. Plan for two different profiles.

The initial profile should be about 20% thicker than anything you might have used before! It’s a strategy that allows the blank to survive the rigorous forming process with better radial integrity.
The second will be a ‘maturation’ profile that you impose immediately on the finished blank before it has time to dry and set up new memory.

LITTLE BASSOONIST ASKS: “I’M AFRAID TO TOUCH MY PROFILER. HOW DO I GO ABOUT THICKENING MY INITIAL PROFILES WITHOUT THE NIGHTMARE OF ADDING SHIMS, fooling with ADJUSTING KNOBS, OR FIDDLING WITH A BLADE THAT TOOK WEEKS TO GET RIGHT????”

Changing the initial profile is not rocket science. All profiling machines use a roller bearing on a carriage guide. Simply add strips of thick adhesive tape the full length of the guide to raise the cutting assembly and thicken the profile. You can use masking tape – start with 3 or 4 layers, or duct tape – 1 or 2 layers. A longer lasting solution is glue a strip of thick teflon using contact cement or a thick cyanoacrylate glue.

Of course, a better solution is to dive in and adjust the cutting depth of your machine. If you are sharing a profiler in a school environment, make sure to take clear notes of what adjustments you have made and then return the machine to its initial configuration.

The very best, absolutely most valuable solution of all? Hand profiling!! That deserves a full chapter by itself…

But what on earth is a ‘maturation’ profile?

This is the most important application of the ideas presented in this chapter.
It’s all about setting up your blanks to undergo the drying and aging process in a way that establishes ideal radial structure in the wings. Just like the laminated furniture, you want to take advantage of the new radial resilience that is imprinted in Arundo donax during the blank formation process.

There are two distinct approaches.

– If your reed making practices involve building a blank and letting it dry/age before cutting the tip, you should expect that the ‘topology’ that you see in the wings will be reinforced in the radial memory of the cane. That usually means that there will be a kind of neutral aperture in the wings when you finally cut the tip – neither strongly convex nor strongly concave. You will be accustomed to dealing with this aperture shape and it may or may not be serving your ideal tonal and embouchure needs. The downside to this approach is that a strong irregularity in one quadrant will still assert itself, and you will have to correct this when trimming.

– If your practices involve building a blank and immediately cutting the tip you will be able to make an instant assessment – both visually and with physical flexing – of both the symmetry and the concavity of your wings. Any imbalance that you leave at this point will be imprinted to some extent and you will have to correct this in the trim. However, if you make immediate corrections before placing the blank on the drying board, you will create an immediate imprint for symmetry during the initial rest – whether it’s a day or a month. Ultimately, this second approach is likely to give your reeds the desired shape with less cane removed from start to finish.

Great bassoon reeds are most likely to emerge when we respect the irregularities of organic material. Adjustments to your reed making that increase mass and density in the early stages will bear fruit in the long run. Less wasted time at the reed desk?

Certainly more time for donuts and coffee..

Here is a link to a presentation given on Symmetry in reed construction. You may find this helpful in terms of implementing the concepts above!

https://www.youtube.com/@councilofcanadianbassoonis1487

Text by Christopher Millard

Drawings by Nadina

Read more about Christopher Millard. Chapter 1 – The Craftsman Chapter 2 – Can you explain how a bassoon reed works? Chapter 3 – Surf’s up! Chapter 4 – The Physicist’s Viewpoint Chapter 5 – The Big :Picture Chapter 6 – We’ll huff and we’ll puff… Chapter 7 – Look Both Ways Chapter 8 – Dialogue Chapter 9 – The Big Bounce Chapter 10 – The Incredible Shrinking Bassoonist Chapter 11 – A Useful Equation Chapter 12 – Goldilocks’ Dilemma Chapter 13 – Stairway to Heaven Chapter 14 – Reed MyLips Chapter 15 – Resonance Chapter 16 – Corvids & Cacks Chapter 17 – Lift Chapter 18 – Chickens and Eggs Chapter 19 – Chiaroscuro Chapter 20 – Donuts Part One / Donuts Part Two Doodles & Design by Nadina

Donuts – Chapter 20 – Part 1

by Christopher Millard | Dec 13, 2022

Brains and Membranes

Bassoon Reed Making by Christopher Millard

Chapter 20 – DONUTS – Part 1

Visualizing form and function is a critical skill in achieving better reeds. If you can imagine a clay coffee mug emerging from a donut, you might also see how the reed aperture morphs from the reed tube. In this chapter, I’ll explore the transformation of reed geometry from the butt end to the tip aperture and discuss how that evolving radial structure influences the behaviour of the reed.

Imagine a coffee mug made of modelling clay. You probably saw a demonstration of this idea in high school, where donuts and coffee mugs were used as an introduction to topology, a field which considers how an object’s shape can be substantially deformed without losing its core properties. In this case, just one hole!

Okay..this model is not quite right, is it? In actual reed making tube cane must first be cut and folded, which alters its identity as a ‘one hole’ object. Though we start with a single stick, the reed emerges from two flexible planes, which we shape, contort, and bind together. Only after building your blank can we go back to visualizing the reed as a long, extruded, and deformed donut!

Let’s do a quick overview of an actual bassoon reed. We start with a tube of cane – diameter @ 25mm – split it into quarters, gouge out the soft pulp on the inside, then using a shaper we remove enough from each of the pieces to create our typical arrowhead flare. This modified ‘stick’ is just a slightly rounded quadrangle, with a curve matching the original growth radius of the cane. It’s a memory of life in the field! As we gradually deform the material to follow this imposed shape, we must both reduce and expand that initial growth radius.

Consider the transformation of that piece of cane. Molding the butt end to a conical mandrel and binding it with wires and string produces a tube with about a 5mm interior diameter. Now, follow what happens with the ever-widening shape. There’s a gradual expansion of the curvature all the way to the tip aperture, where a cross-section suggests the radius of a much larger tube. You’ve significantly reduced the original growth radius in the tube and greatly expanded it in the aperture. Somewhere towards the mid-point of your finished reed, you’re likely to find a curvature matching the original growth radius of the cane. That’s a happy place for the cane, a kind of neutral position where the material is experiencing the least altered radius and the least internal stress.

Our forming techniques are necessarily aggressive, securing both a fitting for the reed on the bocal and a comfortably open radius for the embouchure at the other. All the shrinkage and expansion of the radius from bocal to tip places demands on the innate elasticity and resilience of arundo donax. The reduced diameter sections will try to spring open, requiring brass wire to harness the outward radial force. At the other end, the much-expanded radius at the reed tip will be inclined to close, requiring longitudinal strength to counteract the inward collapse.

Despite the forces we impose on the curvature of the cane, there will always be some residual memory of its original growth radius! It’s important to understand that our profiling and construction techniques encourage additional ‘imposed’ memories. We need to manage and balance these conflicting opening and closing tendencies. .

To understand the concept of an ‘imposed’ memory in wood, let’s imagine a curved laminate chair. Curved wood furniture is made by subjecting wood laminates to heat and moisture, producing permanent changes in the form and the resilience of the material. A piece of plywood can be transformed into an elegant piece of furniture which behaves as if it the wood had naturally grown this way.

Let’s explore what happens when we shrink or expand the natural curvature of cane. Earlier in this blog series I mentioned the term ‘elastic modulus’ – which is a material’s elastic resistance to deformation under stress. Cane demonstrates elastic modulus in both radial and axial [longitudinal] dimensions. That’s just a complicated way of saying that cane is flexible in three dimensions. Shrinking the radius of the tube is like tightening a violin string, creating more internal tension and more resistance to vibration, and a tendency to vibrate at a higher pitch. You might expect that expanding the radius thru the blades to the tip would be akin to loosening a string, producing less tension and slower vibrations. But this is not actually the outcome, because a deformation to a larger radius is still flexing and stressing the cane, and it still wants to return to its original radius. Think of it this way: if you constrict a 25mm diameter tube into a 10mm diameter tube it will want to open and if you force that same tube into a 100mm diameter it will want to close. Now, both actions stiffen the cane, but the radial enlargement out towards the tip occurs in softer material due to the profiling. More on this in a moment.

Arundo donax wants to retain the resilience of its original growth radius, but subjecting cane to the heat and conformational stress of blank building ‘overwrites’ much of that radial memory. The response of cane to mandrels, pliers, heat, and moisture becomes a permanent part of the reed’s identity after it dries.

We need a way to make Arundo donax pliable enough to establish and maintain this new curvature memory. Our principal tool is the profile. Without the removal of the bark, and the parenchymal material beneath it, we wouldn’t achieve all the necessary contours; nor could we take acoustical advantage of the more flexible material in the softer parts of the cane. This allows reed membranes [blades!] to respond to the complex pressure oscillations within the bore. Profiling reed blades gradually attenuates the innate radial memory of the cane, gradually weakening the elastic modulus along the longitudinal axis of those blades.

Subjecting profiled cane to heat, moisture and stress allows new curvatures to dominate the original radial memory.

In Chapter 18 of Brains and Membranes, I described balancing ‘shell’ and ‘fixed bar’ behaviour. I’ll jar your memory: shell physics are strongly correlated to radial elasticity, fixed bar physics with axial [longitudinal] structure. These are the Yin and Yang of reed mechanics – not distinct or separate behaviors, but rather aspects of an integrated view. Membranes, trampolines, diving boards, etc… It’s where elasticity meets structure and delivers acoustically efficient response.

This rather esoteric discussion of the topological structure of reeds boils down to visualizing how the changes in radius might impact the stiffness of cane at any axial point in the blade membranes. We often get unexpected and unwanted irregularities in the radial transitions from collar to tip. I think intonation, response, and sound quality depend on successfully managing the transformations from small to larger radius.

Radial compliance is bound to the shell behaviour of the membranes
Axial strength reflects the functioning of the fixed bar and the longitudinal strength of the reed

Axial structure is just a fancy way of describing longitudinal stiffness… Diving boards, twanging metal rulers, etc… Some profile elements exaggerate longitudinal strength – spines and rails are the obvious examples. But axial integrity relies on more than profile design; our dimensions and our methods of tube construction are critical. Mandrels, shapers, wires, bevels, wrapping and glues all influence the longitudinal resilience of your reed and modify the contribution of fixed bar longitudinal behavior.

In Part 2, our Little Bassoonist will try to make practical sense of this…

Illustrations by Nadina

Text by Christopher Millard

CHIAROSCURO Chapter 19

by Nadina Mackie Jackson | Apr 27, 2021

Brains and Membranes

Bassoon Reed Making by Christopher Millard

Chapter 19 – CHIAROSCURO

Light & dark

Caravaggio and Corelli, one a painter, the other a tenor. Both transcendent masters of the balance of light and shade.

Our Little Bassoonist has studied Caravaggio’s paintings, his human figures illuminated by shafts of light, the backgrounds indistinct, shadows balancing the highlights. She has listened to Corelli’s recordings, his spinto tenor lyrical yet powerful, perfect bel canto balancing a velvety depth with piercing projection. So how does she imagine an ideal bassoon tone? She has heard endless advice about making a ‘dark’ sound, an adjective that seems equivalent to ‘beauty’ for many modern bassoonists.

Our Little Bassoonist has studied

If a dark room implies the absence of light, then a dark tone must imply the absence of – what? Higher frequencies? Or perhaps ‘dark’ just means an abundance of lower frequencies, like a room filled with shadows. LB instinctively associates dark with low frequencies and bright with high frequencies and she’s on the right track. But for a complete picture of bassoon tone, we need to consider the kind of frequencies.

In previous chapters, we have examined how bassoons harness the energy supplied by the pressure-controlled reed and animate the natural resonance frequencies of the bore via complex standing waves. These true harmonics are selected by damping a broad range of unnecessary frequencies in the vibrating reed. Along with embouchure, this interactive process described in previous chapters dampens unwanted elements of the reed’s overly broad tonal spectrum. It is a bit like mixing paints: Caravaggio’s palette included primary colors, but he carefully muted and balanced his tints to achieve skin tones within the visual light spectrum.

When we first see a painting utilizing chiaroscuro – light/dark – we are as much struck by what is obscured in shadow as we are by what is revealed in the clarity of light. A great bel canto voice presents a similar balance and an aspirational ideal for the bassoonist.

So, why is it that ‘dark’ is generally admired while ‘bright’ is often a pejorative? I think one way to talk about these adjectives is to define them in terms of spectrum analysis. In earlier chapters we looked at audio spectrum graphs, which focus on the frequencies of true harmonics. These graphs show a certain amount of energy distributed among the fundamental and the overtones – for each note, each bassoon, each player and each reed. While most of these spectrum outcomes are determined by the instrument itself, the reed and the embouchure play important roles by increasing or decreasing the relative strength of the many overtones. A measurable increase in the lower harmonics leads to a sound often described as darker, while increasing the strength of the higher harmonics leads to a brighter sound.

Remember, while the specific frequency of each harmonic is defined by nature’s simple ratios to that of the fundamental, its relative strength (its amplitude as shown in the spectrum graph) can be modified to some extent by reed design and embouchure use. Our Little Bassoonist wonders why we can’t measure the dark/bright balance of a reed by simply measuring its harmonic spectrum in real-time. After all, we seem to have plenty of good audio spectrum applications using algorithms that convert a sound signal into a graphic representation of frequencies. But these only take a ‘snapshot of the average levels of each of the component harmonics. Much is left out of the evaluation, including the complex beginnings of notes – we call these attack transients – and the ongoing presence of unpredictable inharmonic components throughout the sustained tone. It’s like the difference between a charcoal sketch and a full-blown oil painting. The problem with relying too much on spectrum analysis is this: our ears are considerably more sensitive to complex sonorities than these simple computer applications.

The phenomenon of attack transients is common to all orchestral instruments: it’s the quick negotiation phase between initial energy input and the establishment of a steady, periodic regime of harmonics. For the bassoonist, these range from the obvious (poorly vented mid-range attacks) to the subtle (perhaps that little chirp in tenor Eb?). Once a steady tone is achieved, we become aware of inharmonic components that continue throughout the duration of a note. You all know these as buzz, rattle, sizzle or just plain ‘noise’. So, while a spectrum graph may clearly show energy peaks in the first 5 or 6 true harmonics – suggesting a dark sound – the brighter inharmonic transients simply won’t appear on the graph. Those components not being generated by the bore of the bassoon are too ephemeral to be easily quantified. Instead, these are reed-generated frequencies – non-harmonic and unpredictable – and they can contribute a LOT to the character of the bassoon tone.

There is an analogy to be made to a spoken conversation between two people, where words and ideas may be deep and resonant despite the occasional stutter or mispronunciation. We should keep in mind that the bassoon/reed dialogue ultimately aspires to emulate singing. Spectrum analysis tells us something about what is true in the acoustics of sound production, but actual listening reveals what we deem to be beautiful.

It should come as no surprise that a reed constructed from organic material and cleverly sprung to maximize energy input and acoustic output will naturally contribute all sorts of extra frequencies. Good reed making strategies, combined with skilled embouchure, regulate these anomalies. We’ve examined throughout this blog that the bore of the bassoon does the lion’s share of the work, setting up a regime of organized standing waves and discouraging non-harmonic oscillations, but the bassoonist’s lips and blowing strategies play important roles in attenuating unwanted sounds.

2021 is Franco Corelli’s centenary. Thank heavens we don’t need spectrum analyzers to appreciate his tonal resonance and complexity. But aren’t you a bit curious….? I suspect that the unmatched squillo in his voice was achieved by the cultivation of fairly true upper harmonics.

In a long orchestral career, I have tried to balance my instinctive preference for a ‘covered’ sound with the need to project in a large theatre. Too dark a sound can lead to a lack of both clarity and projection. Students of my generation were told to ignore the closeup noise of a reed, with the understanding that transients and inharmonics would be largely attenuated by distance. I was often advised that without some sizzle I wouldn’t project. Of course, this advice has a logical basis; human ears perceive higher frequencies with more clarity. You will always hear a piccolo carry over a viola.

Distance is critical in an art gallery, too. Imagine you are standing inches away from a Rembrandt, close enough to see the brush strokes and tiny splashes of colour. An eye springs to life with a mere speck of white dabbed on an iris. Up close it’s a bit messy, but at a distance it seems utterly refined. But are we bassoonists necessarily obliged to follow the same principle, using inharmonic ‘tints’ to project rich character to an audience?

Each of us bring our personalities to our tone production. Some of us are bold and outspoken, others naturally understated. Many bassoonists love to produce some extra ‘stuff’ in their reeds – a touch of frizzante if you like. Experience has taught them that an overly sizzly sonority is often heard at a distance in perfect balance. Others [I include myself] are more inclined to produce a ‘finished’ up-close tone. The question is: while a sparkling reed will darken at a distance, will a velvety, covered reed actually go the distance??

A critical question for our role in the symphony orchestra. The answer depends on several rather large factors:

some bassoons produce a broader and more complex range of component harmonics
some concert halls are more friendly to the lower range instruments of the orchestra
some ensembles are simply more transparent and balanced than others.

Projection is never just an acoustical quality; it’s about understanding when to play louder, use vibrato to increase tonal complexity or employ exaggerated nuance to help your musical personality carry. A well-shaped phrase supported with a well-developed airstream will travel an extra 50 feet. Musical depth and respect for your acoustical environment are as important as skillful reed making in achieving projection.

I had the great fortune to spend the first few decades of my orchestral career working in both a frequently recorded symphony orchestra and a separate radio orchestra. These gave me an opportunity to listen to my sonority and projection in both a large concert hall and a recording studio. As my reed making and my musical abilities evolved, I was able to evaluate my sound development on broadcasts a couple of times a month for many years. The experience persuaded me that a reed that is satisfying up close can also achieve good projection in the concert hall. The key is maximizing the strength of the higher harmonics while minimizing unwanted transients and inharmonics.

Our little bassoonist [Miss Caravaggio, now] is looking for some simple rules to guide her in mixing her tonal palette.

So, here are some principles to consider…

So much of the character of the bassoon, or any instrument for that matter, depends on the first few milliseconds at the start of each note. This is the opening dialogue between bassoon and reed when initial non-periodic frequencies are quickly dampened by the dominating standing wave regime within the bore. These attack transients, in their most obvious form, are the reason we use flick keys, discouraging the lower 1^st harmonic by creating a disruptive leak in the tenor joint.

Attacks grow more complex as we ascend the ladders of the various ranges; how much of these transients we choose to employ will depend on our artistic personalities. Many players [mea culpa] work to minimize the presence of unwanted harmonics in the upper register attacks, while others love to have the extra character in their articulations and cultivate profiles that deliver these ‘peppier’ attacks. Of course, these choices can also be repertoire-driven.

While attack transients are most obvious at the beginning of tongued notes, they also remain subtly present in legato passages. Slurring between adjacent notes within one register tends to reduce the interactive dialogue between bore and reed to an absolute minimum, yet some reed profiles will exaggerate even these very minimal components. Once a sustained tone on any note is achieved, we can begin listening for some of the ‘extra stuff’ in the sound: transient/impermanent components that bubble up to the surface.

If you’ve ever played on a plastic reed, you will immediately notice the absence of all of this ‘extra’ acoustical information! Arundo donax has unpredictable, complex internal structures that contribute tonal complexities mostly absent in a synthetic reed.

Loudness plays an important role in the contribution of transients in the sound. The louder you play, the greater the tendency for the ‘extra stuff’ to emerge. Bassoonists tend to rely on a rebalancing of dark and light to exaggerate the effect of a crescendo. The typical change of character between piano and forte can be an essential tool in establishing our personal tonal objectives. Some players choose profiles that utilize significant increases in non-harmonic content during a crescendo. Others will prefer to utilize ‘noise filtering’ strategies in their reed trims – often by using thicker profiles and larger overall dimensions. My observation over the last 50 years of orchestral bassoon playing is that we’ve seen a shift in the dark/light preferences of performers and conductors. You could say that bassoon tone has become ‘warmer’ – although that is a highly subjective description. You could also say that bassoon tone is simply ‘darker’ than it was decades ago.

We have already established that the word ‘dark’ is a confusing concept. I think a better description might be that we’ve undergone a shift in our ideals of refined bassoon tone. Bassoonists understand the importance of true higher harmonic frequencies in their sound production but are a bit more cautious now in controlling transients in attacks and avoiding too much buzz at higher volumes. What has emerged is the idea of a chiaroscuro that cultivates both shadow and clarity but leaves some of the rougher character of cane in the marshes where it grew.

At this point in yet another challenging chapter, our little bassoonist needs some guidance as she takes a knife to her reeds. So, let’s look at a really simple principle that governs certain kinds of vibrating objects:

Non-harmonic content is inversely proportional to dampening [a vibrating system with a longer potential decay period]. It will take the dialogue between bore and reed longer to establish a steady regime of harmonic oscillation.
Conversely, a vibrating object whose natural frequencies are quickly dampened will demonstrate shorter attack transients and fewer non-harmonic components.

Here is a thought experiment: imagine your reed’s natural frequencies could be induced by whacking it against your knee like a tuning fork. You can sort of imagine the reed briefly ringing like this, but the sustained ringing of cane is significantly shorter than the steel tines of the tuning fork. You can also imagine that a thinner profile will vibrate longer than a thicker profile, as will a reed constructed with more resilient cane. The more wood left on the profile, or the mushier the wood, the quicker this dampening process occurs. Quick decay reduces transients.

A possible way to visualize the relationship between long decay and non-harmonic behavior would be a very loosely strung guitar string. Pluck it and the string will vibrate wildly, buzzing and colliding with the fingerboard. But as the string is gradually tightened and brought up to pitch, you will see it quickly organize into predictable waveforms.

Many experienced reed makers begin with profiles that are intentionally too thick and patiently remove cane to achieve adequate compliance (sufficient vibration). Heavy reeds in that early trimming process generally demonstrate very little in the way of attack transients or extra ‘noise’ in the sound. And we probably don’t notice! Usually, when we test overly thick reeds, we’re entirely focused on the resistance and the sharpness, so we probably won’t notice the absence of transient inharmonics. Trimming down sharp, heavy reeds to proper MCA values will deliver properly tuned reeds with a broad spectrum of harmonics, but we have to be careful not to go too far. And it’s not just to avoid flatness. Thinning reeds too much can lead to more buzz in fortissimo and more pop in the attack than we might like.

There is certainly not a correct light/dark balance: chiaroscuro is a highly subjective concept in both art and music. Corelli found his by combining bel canto techniques with lucky genetics in his vocal physiology. Maybe our Little Bassoonist will find hers adapting reed profiles to match her lips, teeth, mouth, air column AND artistic temperament. But she’ll do better if she can understand the main source of the ‘extra stuff’.

Bassoonists who prefer smaller reeds need to remove more cane to play with resonance in the A=440 world. Success here typically involves specific profile strategies. For example, some of our great players make reeds with very thin ‘channels’ as a way to deliver adequate compliance. Others rely on a stiff spine and let tip and sides vibrate more freely. There is always an acoustical requirement to match cane flexibility and reed dimensions. Smaller reeds have less margin for error in finding correct MCA values without losing control of chiaroscuro.

When done well, these lighter reeds become Corelli in character, with boosted higher partials and just a touch of inharmonics. They’re fun to play, too. Bigger reeds, using larger and thicker profiles, produce smoother and woodier sounds with more relative energy in the lower harmonics, a bit less of the upper harmonics, and much less transient character in the attacks.

Let’s give LB a simple rule:

Profiles that feature very thin areas will tend to produce more of the transient frequencies in the attacks and more tendency towards brightness and inharmonic noise in louder dynamics.
Profiles with thicker cane will tend to produce less of these transients

Think like Caravaggio! Thicken your sound with dark umber before gradually thinning to an iridescent silver.

Finally, please consider this: like Corelli, your ideal bassoon tone is an unavoidable extension of your body and your personal identity. It will be tightly linked to your physical tolerances and tonal preferences. Your responsive embouchure and adaptive air column are critical in emulating the human voice.

Like Corelli, you’ll need to balance the light with the dark!

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CHICKENS AND EGGS – CHAPTER 18

by Nadina Mackie Jackson | Feb 28, 2021

Brains and Membranes

Bassoon Reed Making by Christopher Millard

Chapter 18 – CHICKENS AND EGGS

Which came first?

Matching profiles, shapes and dimensions are critical steps in reed making. As I argued in Chapter 11 – A Useful Equation – there is a logical balance between volume, mass and compliance. To satisfy the bassoon’s need for a workable missing conical apex, larger reeds need decreased compliance and smaller reeds need increased compliance. It’s a simple relationship: more flexibility is required to make a small reed happy, less flexibility is necessary for the larger reed, so we make thicker profiles for Papa Bear reeds and thinner profiles for Baby Bear reeds. The principles of dialogue, response, resonance and tuning underly this basic relationship between size and flexibility.

Reed design takes on a whole new level of complexity when we discover that different kinds of profiles seem better suited to different sized reeds. Spines, rails, tips, channels and hearts are all part of our vocabulary and how we visualize our ideal designs. It seems clear that different profiles seem specifically suited to different shapes and dimensions. As we experiment and evolve, we juggle back and forth between changing shapes and changing profiles. Experimentation and an open mind will always lead to new investigations. Try this, that…soon we are overwhelmed with variables. But what comes first…the profile or the shape?? To answer this, we need to do a brief dive into an area of reed physics that I’ve not yet addressed.

When I was a young student at the Curtis Institute in the early 70’s, I made weekly pilgrimages to the Academy of Music to hear the Philadelphia Orchestra. Bernard Garfield’s extraordinary artistry illuminated every passage he played. The tone was always resonant and warm and proved the perfect vehicle for his sophisticated musicianship. Though he was not my teacher, I studied his preferred approach to reed dimensions and profiles. Garfield’s profile included a delineated tip area, a spine, a pronounced heart and thinning of the sides to bring this smaller dimension reed into perfect tuning.

Most of you will have pursued some form of this very standard, heart-focused profile. It’s a really good model and one that made a lasting impression on me. As the years passed and my own preferences for response, embouchure, and tonal character evolved, I began moving to larger reeds with longer tip tapers, eventually eliminating that little area of thickness that we call the heart. Despite the fact that I was getting better outcomes, I struggled with letting the heart-focused profile go. That early imprint nagged at me, like a commandment that I disobeyed with reluctance!!

For years I have assumed that my long tipped, heartless reeds sounded fine because that profile simply works better for the larger dimension reed. It’s an observation made by many of us who lean to larger reeds. But I’ve also come to appreciate that the heartless profile works better because of my embouchure and my preferred ‘effort level’ [Chapter 12 – The Goldilocks Dilemma]. Long tip tapers demand a different relationship between embouchure damping and air delivery. Let me explain.

There is a range of preferences to how we achieve a tapered diminuendo in our playing. At one end of the spectrum are players whose embouchure, air and reed trims allow diminuendo to be produced by emphasizing reduced air supply. At the other end of the spectrum are players who tend to use increasing embouchure dampening during a diminuendo and must therefore supply more air support to compensate for the increased inertia in that dampened reed. Of course, we all experience our dynamic nuances at various points of this continuum; different profiles lean one way or the other.

I hate to make a broad generalization about profile characters – because there are variables that may disprove every assumption – but I think the more we tend to use embouchure dampening for a complete diminuendo the more likely we are to relocate and reduce the ‘heart’ of a profile. Contrarily, the more we prefer to produce a diminuendo by simple reduction of air supply [and keep a more relaxed embouchure] the more likely we are to emphasize a ‘heart’ forward reed.

Different profiles respond to embouchure dampening and changes in airflow in different ways. Profiles with a strong backbone [spine] focus their longitudinal structure down the middle of the membrane. [We can use the word ‘axial’.] Profiles with open, thinner spines transfer structural resiliency to the sides and rails. These contrasting profiles are inverted images of each other, and each represents a different expectation for the orbicularis oris muscle group. Though young reed makers initially think in terms of a single pitch range and a single volume dynamic, we learn to visualize how embouchure and air interact with different profiles and adapt to all registers at all volumes.

Most of my descriptions of the blades of a reed have emphasized the three-dimensional view of membranes as shells containing and responding to standing waves within. The missing conical apex model is reasonably good at predicting the interaction of volume/size and compliance in designing acoustically responsive reeds. But let’s branch out here and consider the behaviour of the blades in a simpler two-dimensional context: the idea of the ‘clamped bar’.

Diving boards are a great example.

You can get a really good idea of how length and stiffness effect both amplitude and frequency in a clamped bar. Take a metal ruler and hold one end on to a table, letting most of the length sit free. Give it a good “TWANG!” …

Shortening the free length of the ruler increases the frequency of oscillation because pitch rises and falls according to the free vibrating length of the ruler. This is a classic example of the elastic properties of a linear object like a reed blade. There’s a beautiful equation covering these relationships of stress and strength, expressed in Young’s Modulus. Thomas Young [1773-1829] is right up there with Bernoulli in my book. He’s responsible for the wave theory of light, too. Smart guy, but never played the bassoon.

When we observe a clamped bar, we are seeing something oscillate at a natural resonating frequency, with no external influences. As the past 17 chapters have argued, bassoon reed oscillations are primarily controlled by the standing wave within the bore. Compliance slightly modifies frequency – the flexibility of the cane determines the efficiency with which the pressure-controlled valve operates. It’s reasonably easy to visualize how the membranes function as servants to the internal bore frequencies – remember trampolines and tympani heads? But when we shift our attention to the diving board viewpoint – the blades as two-dimensional clamped bars – we see that profile variables influence pitch according to which notes on the harmonic ladder we’re playing [Chapter 13 – Stairway to Heaven]. A deeper look at the metal ruler behaviour will help us in seeing the effect of profiles on the two-dimensional behaviour of a reed blade.

Young reed makers are frequently presented with diametrically opposed observations about how thickness and dimensions influence pitch. One school suggests that removing cane lowers pitch; the next says that removing cane raises pitch. If you’ve made enough reeds, you will know that both statements can hold true. It all depends on other variables. The acoustics of the reed/bassoon dialogue depend on the interaction between two interacting sets of physical behaviours. One group focuses on the membrane – ‘shell’ physics if you like – and the other focuses on the blades – clamped bar physics.

Diving boards are a great example.

Twang!!!

Your twanging ruler is a somewhat limited representation of the behaviour of the reed blade because this metal bar has uniform thickness, width and stiffness. Reed blades are considerably more complex as they have variable width and decreasing thickness from throat to tip, and variable compliance due to internal cane structure. And never forget – your ruler’s vibrating frequency is not being controlled by a standing wave; its behaviour is entirely determined by its own dimensions!

Twanging metal rulers will be sharper if the steel is thicker, flatter if they are wider, sharper if they are shorter. But what happens with your ruler when you change its thickness in one specific area? This is actually quite easy to test. If you glue/tape a bit of cardboard to the tip of the ruler you will discover the twanging pitch will drop! Adding mass [front-loading] to the tip of the clamped bar lowers its natural frequency. Now try adding some material towards the fixed end. Back-loading mass here will raise the frequency.

Do you see any parallels in your reed trimming experience? Leaving tips thick will typically tend to lower pitch just as leaving backs thick will typically raise pitch. Now, while distribution of mass on the clamped bar explains this relationship, remember that much of the complex physics of a reed is governed by the three-dimensional interacting factors of the membrane shell and the internal standing wave. Nevertheless, this alteration of mass at the tip and its effect on pitch is frequently observed, even though it seems at odds with the behaviour of membranes and shells.

Here is the paradox: while increased membrane thickness as a whole decreases reed compliance and raises pitch, increasing thickness at critical points of the profile can lower pitch. Furthermore, the pitch effects of front-loading or back-loading mass are exaggerated as we move to higher notes. A perfectly content reed with an ideal MCA for response in the bass clef is often flat in the tenor range if the tip region is too thick.

These confusing inconsistencies between the sharpening effect of thicker blades and the odd flattening effect of thicker mass at the tip of the reed can drive you crazy. Implementing the principles of the MCA theory [volume, dimensions and compliance] will get you most of the way to a functioning reed, because the bassoon’s standing wave frequencies tend to dominate the three-dimensional physics of membranes. But the critical final trimming that delivers a musically flexible reed must be increasingly respectful of the two-dimensional physics of the blades as clamped bars.

Shell physics and bar physics engage in dialogue with the bore in differing ways; the push and pull of their interactions lead us to develop profiles that are comfortable for our individual embouchure and air preferences.

Courage in Profiles

So, with apologies to crows everywhere, I pose the question: what comes first – chicken or egg? In biology this question is rhetorical and circular – each proceeds the other in an infinite cycle. But in reed making, profiles may indeed come before shapes. The intuitive, tactile relationship between lips, air, and vibrating reed is [like the egg] the starting point. We incubate and nurture with our embouchures and our shapes and measurements evolve to get the best out of our individual sound production preferences.

In the next chapter, we will look at some of the predictable tonal outcomes when we choose certain profiles.

Chapter 19 – CHIAROSCURO

P.S. There is a wonderful new book on reed making by the former Houston Symphony bassoonist Eric Arbiter. It’s an extremely practical and beautifully organized book about many aspects of the reed-making craft. The Way of Cane – published by Oxford University Press. When my philosophical musings about reed acoustics become overwhelming, Eric’s book illuminates a practical path to finding success in your individual reed making.

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LIFT – CHAPTER 17

by Nadina Mackie Jackson | Feb 11, 2021

Brains and Membranes

Bassoon Reed Making by Christopher Millard

Chapter 17 – LIFT

Those of you who have patiently followed this blog for several months might be longing for some practical information rather than the fanciful analogies about conga lines and trampolines. Sorry, I have one more holistic concept to impart. It’s one that helps me analyze what I feel and hear in the initial trim.

Little Bassoonist would love to fly as much as she would love to master the bassoon. She dreams of soaring above the clouds and humming Jolivet. She’s not particular about what kind of plane. A glider will do, or maybe a compact Cessna for those weekend flights. Sometimes she sees herself immaculately garbed as an airline pilot, flying a 300 tonne Airbus, and on those passive-aggressive days – she’d happily pilot a stealth fighter!

Anything to get up in the sky.

Reeds and airplanes are bound by a common thread because they are both dependent on airflow, especially the relationship between air velocity and surface pressure as expressed in the Bernoulli theorem. The typical curved top/flat bottom shape of an airplane wing produces accelerated air flow and reduction in surface pressure on the top wing. The V shape of a bassoon reed causes acceleration of airflow and a continual tendency to pull the blades together.

Thinking about different kinds of planes is a bit analogous to thinking about reeds. Ultralight planes have tiny engines and low mass -something like those effortless Baby Bear reeds that allow us to float with nuance and ease in the third octave. A single engine Cessna is heavier, but it’s still nimble and efficient in the air, like a good flexible Momma Bear recital reed. On the other hand, that big Airbus requires 50,000 HP engines to get off the ground. But they can carry huge loads and go long distances – like the requirement to project a solo passage in a 90 player orchestra.

What are the primary factors to consider in achieving flight? The plane needs enough lift and thrust to overcome the weight of the plane and the drag caused by friction during forward motion. What’s this have to do with reed making? Well, meditating on these factors might help you get your head away from dial indicators, refresh your thinking and get you up off the ground…

4 flight factors, thrust, drag, weight, lift, bi-plane

The factors shown here represent the forces on a plane moving forward through the air. By shifting perspective a bit we can see similar force when air is moving forward through a reed (below).

The adjustment in this diagram allows us to visualize thrust as the airflow from the player and drag representing inertia and resistance in the reed.

The challenge in writing this ‘philosophical’ blog about reed making is finding concepts and ideas that are inclusive for a broad range of bassoonists. I’m always searching for images and analogies that might illuminate highly divergent individual techniques. Fifty years of reed making has taught me that a very broad range of profiles and measurements can still be brought to the service of the specific tonal and performing preferences of an individual. In other words, I believe that we will always tend to produce the sound we want no matter how we vary our reed designs. We can use a Papa Bear reed or a Baby Bear reed and still achieve our preferred sound.

In Chapter 16, I described the acoustical behaviour of reeds unattached to bocal and bassoon. As we begin adjusting our reeds, it can help to visualize each of these four interacting factors.

Each of these four factors has a loose counterpart in the dynamics of a bassoon reed.

1. Thrust represents propulsive energy. No problem there – that’s your air supply.

2. Lift represents how a plane leverages airflow to create reduced pressure on the upper surfaces of its wings. In a reed, Bernoulli ‘suction’ continually converts airflow by repeatedly pulling the blade membranes together.

3. Weight is the mass of the airplane plus its contents – pilots, passengers and cargo. In a reed, we can think of this as the static mass of cane that is resisting vibration – dimensions and profile thickness mostly.

4. Drag measures how efficiently the airplane’s external shapes cut through the atmosphere. For us, this might be a measure of inconsistencies in cane structure, profiling asymmetry and embouchure dampening.

So, let’s examine the crow from a pilot’s point of view!

Little Bassoonist is dreaming of her cockpit. She is reviewing the manual. This small plane requires her engine to run at 1700 RPM for takeoff and with a normal load she will become airborne at 60 mph. The instruments deliver precise information for a safe and predictable flight. But what would she do without an instrument panel? I expect an experienced pilot might remember the sound of the engine at 1700 RPM and have a visual memory of what 60 mph looks like.

Back at her reed desk, LB is reviewing all the recommended measurements from the manual her teacher has supplied. She has an expensive dial indicator and a sharp profiler blade! The blank in her hands precisely matches all the assigned measurements. Unfortunately for LB, her reed is not a precision piece of technology; it’s wood. No amount of measuring is going to assure her of a good take off. But like that experienced pilot, LB can remember what appropriate air flow feels like.

With the blank in her mouth for the first time, she gently tests out this ‘remembered’ air flow. Is the ‘thrust’ sufficient to initiate vibration? If not, she intuitively increases her air supply until the reed responds, at which point she can start listening for peeping pitch, crow behaviour and additional overblown harmonics. [See Chapter 16]

This a moment fraught with uncertainty for young reed makers, and it’s when all the individual approaches diverge. For example:

Is the crow loud and raucous with excessive low frequency components?
Is it a tight and sharp peep, unwilling to open into the complexity of a crow?
Does it feel strong, resilient and vibrant?
Is it stiff like a popsicle stick with very little available vibration?
Is the overall challenge to encourage more vibration or to tame too much vibration?

The Weight/Lift/Thrust/Drag model offers possibilities.

No matter how efficient its wings or engine, a plane with too much cargo will not get airborne.
The aerodynamics of the plane are designed to operate within the parameters of the other three forces. Lift is modified by weight, thrust and drag.
Thrust is determined by the power of the engines, which exert forward momentum via the structure of the fuselage. That thrust is attenuated by the weight [mass] of the plane and by the aerodynamics of the wings.
Drag is determined by the profile of the body and wings and the resulting effect on wind resistance.

In a bassoon reed we see some analogies.

No matter the contours and dimensions,, reeds with too much mass will resist the Bernoulli process. They are too stiff to allow lift.
The profile of a reed is designed to balance structural stiffness with flexible response to air flow and to permit natural embouchure damping.
The driving thrust of airflow is controlled by the blowing preferences of the player in any given musical circumstance. The response to airflow is attenuated by thickness [mass] and the aerodynamics of the profile.
Drag is associated with lack of plasticity in the cane as well as the effect of embouchure dampening.

As we begin trimming, we are faced with the decision of how much to take from the front, sides, middle or back. Many bassoonists start with thinning the tip and then move on to the wings. This technique produces thinner cane in the area where the Bernoulli sucking force is most pronounced – where the membranes in their static position are closest together. The typical thin tip/weak wings/heavier heart profile serves the aerodynamic efficiency for air entering the reed.

I think removing cane is an often-misunderstood process. Always ask, “When I scrape cane in a specific spot will I increase or decrease vibration?” For example, removing cane at the center point of the tip increases amplitude because it ‘leverages’ the prime area for mechanical response to air. But removing cane at the tip corners will usually weaken the membrane and reduce potential vibration. The outcome depends on whether the adjustment primarily enhances the ‘aerodynamics’ of internal flow or weakens the structural integrity of the membrane as a whole.

Aeronautical engineers are skilled at creating strength while reducing mass. Metallurgical advances have produced metal composites that optimize balance between rigidity and flex. Millions of years of evolutionary advances have produced in Arundo donax sufficient longitudinal and radial strength to grow 20 ft tall and withstand all weather. But the cane would much rather be in the field than stuck on a bassoon!

Longitudinal strength in an airplane fuselage is essential to staying aloft.
Longitudinal strength in a reed is essential to staying up to pitch.

Regrettably for us, at the granular level cane is highly inconsistent. We typically find areas of mushiness unevenly distributed between the strong vascular bundles that give the blades rigidity. Softer materials vibrate with less resiliency and at slower frequencies, so they correlate to ‘drag’.

Bernoulli-initiated lift is not the only force that allows airplanes to fly, but it’s the one that seems to apply to bassoon reeds. Here are some points of comparison:

Reduced pressure on the upper surface of a wing lifts the entire plane. That force depends on sufficiently stable connections where wings meet fuselage.
The big variable in the operation of an airplane is the weight of passengers and cargo.
Reeds with too much wood in the back are analogous to an overloaded plane; they’re both going to require increased thrust to compensate for weight.
Reeds with too much wood in the tip – front loaded – are like airplanes with poor aerodynamic design in the wings requiring extra airflow.
Commercial aircraft have to be careful about the distribution of load. If a half full plane seats all the passengers in the front row the plane will keep its nose down, require more power to lift off and present more drag.
Reeds need care in the distribution of load. Too much cane in the tip inhibits Bernoulli lift, lowers the pitch [especially in the higher operational modes] and will be a drag to play…
The backbone of a plane is the airframe within the fuselage. It requires a careful balance between strength, weight and flexibility.
The backbone of a reed, though often presumed to be the ‘spine’, is a more complicated balance between the longitudinal resilience of the fibres, the cellular structure [at the molecular level], the original radius of the plant and the leverage exerted on these factors by the structure of the tube.
Flaps and flexible wings are necessary to manage changes in speed and altitude. Flight efficiency is a dynamic process as conditions evolve.
Flapping, flexible wings in reeds are necessary to manage changes in musical dynamics and registers.
Airplanes don’t fly at fixed altitudes. They must be capable of more thrust and lift at takeoff, and then find cruising altitudes that are more efficient and economical. Pilots adjust wing shapes [flaps] to adapt to these differences.
Bassoon reeds don’t operate in single notes or registers. They must be capable of more lift during attacks and be able to climb the ladders from fundamental to register to 2nd harmonic notes, 3rd harmonic tenor register and on up into the wild blue yonder of the altissimo register. Bassoonists constantly adjust membrane shapes to adapt to these differences.

So, what’s the point of all these comparisons?

I like to think of the two blades of the bassoon reed, interacting in reasonably balanced fashion, as small airfoils. Stretched and extended over lengths approaching 30 mm and maximum widths of 15 mm, these singular membranes are profiled to deliver aerodynamic response unique to the preferences of each player. All of these analogies to flight are a way to focus our attention on the ‘input response’ behaviour outlined in my earlier blog chapters, just as my trampoline analogy focuses on the ‘output response’ to standing waves within the bore.

Cane Plane (from the Archives of the Imagination)

As you think about whether these unusual models have any relevance to your reed making, I’d ask you to begin considering a really important question which I’ll take up in the next chapter. “Should we adapt our profile preferences to match our shapes or match our shapes to suit our inherent profile preferences?”

Chapter 18 – Chickens and Eggs

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