Łukasz Martynowicz

No offence intended, but with this post you have again proven, that you still know very little about observable reed behavior… Some facts then, that you can observe even with a naked eye, actually looking at a sounding reed: Low A=220Hz reed on moderate volume (gravitational pull on the bellows only) has an amplitude of tongue movement of 5mm (10mm total travel) and to a naked eye this amplitude is symetrical and I don't think that there is any significant assymetry even when measured with apropriate instruments. Plate thickness is usually around 2mm, so with your symmetrical design there would be at least 1mm of tongue movement outside the shoe at each side (if your reed would work) . And this is still at moderate volume. Largest bass reeds can have an aplitude easily exceeding 10mm. What you have described in your opening post, about the lift force created on a tongue is finally true - that the tongue is more similiar to a plane wing than a pressure valve and static pressure of the higher pressure side has neglectible direct effect on it's movement. But after carefully analysing your design, I must say that you forget about orders of magnitude of involved effects and in your latest post strongly overrate the effect of a static higher pressure on the tongue. Again, look at the actual reed - even when no leather valves are present to cut unwanted airflow, only the sounding side reed moves, the other just leaks air, it does not bend in any signifficant way. With your model it should bend proportionally to the pressure gradient in the same way as the sounding reed. Please understand, that the whole process of sucking the tongue into the shoe and resonant amplification of oscilation happens at this tiny area near the point on the tip of the reed tongue and the only significant aerodynamic force act only there. Pressure gradient is needed only for creating wind, which moves almost parallel to the shoe and reed tongue "meeting point". What I have overlooked in my first reply to your proposed design is the flow which you think will drive this design in the first place. Now I think that it won't even start or will have a very slight vibration only. Here is a quick picture, that may help you understand the relative values of forces involved, and an actual airflow shape. Little grey arrows represent the higher pressure acting on entire tongue. Blue arrows represent the airflow, which is faster in the areas when the lines are closer together. Green arrows represent the lift force, resulting from the airflow. Fig.1 represents the typicall reed in it's starting position. The lift force is orders of magnitude higher than the force from pressure gradient. The same effect would occur in your design on the upper shoe-edge crossing point if somehow your reed could start. Fig.2 represents your design. You can see how the lift is created on both sides of the tongue, with values much smaller that on the "classic" assymetric reed. The similiar forces (however even smaller) are created in normal reed due to flow through tongue fiting tolerances. See how the upper flow creates a significant dampening force, which I have mentioned earlier. Fig.3 represents an additional lift force created when tongue passes through the shoe. It is again working towards the resting point and propels the resonant oscilation slightly. It is weaker than on the upper side of the reed, because airflow is not instantaneous and it works within a shorter time than on the upper side. To illustrate orders of magnitude of involved forces, I have another quick and simple experiment for you. Take a piece of typical printer paper. Place it at some distance from your mouth, with one of the corners pointing upwards at mouth level (with corner point at a level of the top of your upper lip), holding it stretched firmly in two hands about 5-10 cm from the corner. Then start blowing gently, silently and steady through a small hole between your lips (so the pressure gradient between your lungs and ambient pressure is the same throughout the experiment) and at the same time start closing the paper to your mouth. At some point you will start to hear the slight noise of air accelerating due to obstruction of pathway. Keep closing the paper slowly to your mouth. There is a very distinctive moment (at few mm from the mouth), when closing the paper even slightly closer will rapidly change the direction of the airflow (down along the paper) resulting in a gentle "pat" of the paper corner on your lips. This is the moment when gap suction aerodynamic effect occur, sucking air from above the corner, creating dynamic underpresure on the closer surface of the paper, moving the paper and closing the gap. Note that there will be no audible change in noise volume (but there will be change in tone from a high pitch whistle to a lower pitched noise due to paper dumpening energy). Then fiddle around with blow direction, paper position and blow strenght and you will find a "sweet spot" when a paper stretched between hands will start flapping or even sounding with a reed-like buzzing sound (in addition to a whistling noise of airflow). You can observe that the paper movement at this distinctive point is much stronger that even slightly further away and that your blow force is bending the paper only slightly outwards. This is the physics of a beating reed ilustrated in a simplest experimental form. The physics of the free reed is different in details but general principles and involved forces remain the same.

@ Don: have you seen this guys effort of doing traditional reedpans with hobby-level tools? http://concertinamatters.se/page38/styled-8/index.html @ Geoff: my thoughts exactly. If one wants something bigger than Beaumont, traditionally reeded or with certain tone, then there are absolutely no valid options...

I must say I was expecting something like this exactly, as this design was the first idea that came to my mind when you wrote about bidirectional reed I have only one, but probably "end game" note on this design: you have now effectively two flow cutting points - one in each half-cycle of the swing motion. So while this type of reed will probably vibrate, it will probably has a very low amplitude (only around the central V inset), probably in almost inaudible range. The "agaist the airflow" (I'll call it upper) cutting point works effectively as a very efficient damper. In traditional reed, in the stable oscilation phase, the upward movement above the shoe is almost unrestricted (as we have agreed, that pressure force is much smaller than spring force) and an airflow around the tongue is almost free, and downward movement is accelerated by suction caused by airflow. But now you have introduced a part in the cycle that counteracts the resonant effect which drives the traditional reed. After achieving the upper flow cutting point any further increase in amplitude is IMHO impossible with this design.

From what I have found about asian type reeds on the last couple days, all eastern instruments are mouth blown and require a pipe resonator for reed to work. From my personal experience with a clarinet (which has a beating reed, so physics is a bit different) and from musicians of various wind instruments, I know that you cannot simply attach a bellows to such instrument - to be able to play on them you must first learn how to sound them, how to "manually (mouthually?) jump start" the reed by combination of blow strenght, slight temporal variance and precise direction (probably causing a proper turbulence at the reed point). I don't know for sure that this is a solid fact, but it sounds to me as a very solid reason why bellows driven reeds have to have a different construction and principle (are blown-closing in oposition to blow-opening asian reeds) and are dependant on gap suction mechanism.

I think there is one other way: you could glue a piece of thin plastic (preferably a foamy one) on the button plate itself (not the lever), and make an apropriate hole in it with a sharp, thick needle. The plastic will warp around the needle and fit snugly into existing button hole, imitating exactly what a felt bushing does. As Don, I and Wim (the very maker of the instrument), have said - the problem has nothing to do with reeds or humidity.

I'm very curious about your new bidirectional reed design and looking forward to your thread

Suction effect in fluid mechanics, as well as lift on the wing of the plane, are two emanations of the same effect, generating force caused by speed difference of particle movement, as you have described above. So I really don't understand what you mean by stating that suction effect is not a force (obciously it is not a force field) and then describing this effect on a microscopic level... And because you can hardly expect an airflow around moving tongue to be laminar, then probably turbulence occuring with sudden cut-off when tongue sinks in the shoe is as significant here as in bumblebee flight, increasing the effect of drawing a tongue into the shoe by airflow.

Regarding seting a tongue into movement, this is exactly what has to happen - a lot of air has to move in a wind form, which propagates at a lot slower speeds than soundwave. And my comment on tube dampening the volume was completely missunderstood (probably due to my imprecise language): the tube will dampen the volume and muffle the sound due to lots of bounces of soundwave and resulting energy dampening with each bounce. Especially when it is not a straight air duct but a maze with two straight angle corners like in Jakes design. I have even proposed a simple experiment on that matter for anyone to perform for themselves. Each concertina builder will confirm, that the loudest and brightest ones are the ones most open, with the shortest possible route of air from the reed chamber to the outside of the concertina, with least of the energy dampened in between…

But the reed tongue is not propelled by a sound wave! It is the source of a sound wave, but is set in motion by an airflow at wind speeds! And this sound wave of course is propagating with the speed of sound in the air, and is moving in every direction, including against the airflow and into the bellows… This is completely different than pressure gradient between inside and outside of the bellows, resulting in wind blowing through the reed, air molecules interacting with tongue via airflow etc... You are mixing two different physical terms here. Even when oscilating at full amplitude and making sound, reed tongue movement has nothing to do with sound propagation speed… You can hear sounds as low as 10 hz - that is 10 beats per second, that is about 20 cm of reed tongue tip travel per second, not even close to 340meters per second!

@ rlgph: Yes, I have been reading all your posts carefully, and I'm trying as much as I can to point out to you where you make some false assumptions on how physics of free reed works... One other thing, which is relevant to both this thread and our second physics discussion, which may lead you to understand free-reed physics and wasn't stressed enough previously: air pressure force acting on the reed is much lower than needed to bend tongue to it's maximum position - internal spring force is much greater than maximum bellows pressure force. It is the effect of resonant amplification of small tongue movements that makes this amplitude so large. The pressure in the bellows is high enough only to bend a plastic/leather valve to the roughly same order of magnitude of displacement as an oscilating metal tongue. If you would make an experiment with a typical reed and measure tongue displacement, then your physics is a good description of what can be measured with a pressure acting in the silent direction of the reed. The tongue would bend a little, releasing high pressure - the higher pressure the more tongue displacement - but this displacement would be measured in fractions of a milimeter. And all forces would be equalised at all times, there is no need for aditional "missing time varying force" here. With sounding airflow direction, what happens is this (in as elaborate form as I can think of): at first, when you squeeze the bellows, the air starts to flow through the gap. The suction effect of the gap is signifficant enough to move the tongue a little towards the shoe. Then when there is no more airflow (when reed sinks a bit into the shoe) and suction effect stops, the internal spring force (which is greater than pressure force acting on the tongue) is accelerating the tongue back towards it's resting position, but due to momentum it swings a bit higher than resting position. At this point the suction effect starts again, and acts towards drawing a tongue into the shoe, but this time there is a bit of added momentum from the spring force going back from it's highest position. A cycle closes, but with a bit of added energy. With each cycle the swinging motion increase a bit and after a few cycles the tongue goes through to the other side of the shoe, at which point airflow increases, making each cycle even more influential and within a few cycles the tongue achieves a stable oscilation, proportional to air pressure in the bellows, which now translates to volume (an oscilation amplitude) and frequency. If you want to learn more about the strenght of suction effect in fluid mechanics, then read (and watch) about suction effect of ships passing each other in harbours as this is the most visual illustration of this effect. Or you can take two sheets of paper, hold them down close to eachother and blow gently between them and observe how they will be drawn to each other by a dynamic airflow.

Not entirely true. While the filament doesn't have to wait for individual electrons to travel to it from the switch, the change in the electric field gradient isn't instantaneous. It may seem so to us, but it can't be faster than the speed of "light" (electromagnetic waves) in the wire. But as with the electromagnetic wave above, the pressure change is transmitted at a finite speed... the speed of sound. This happens through collisions between molecules, even though for individual molecules to travel the full distance takes a much greater time, if it happens at all. Nor is there any guarantee that they can... or even that if such a solution does exist, it's easy to find or construct. Jim is right, but this is even more complicated than that, because... …before there is sound produced by the reed, which then travels at a speed of sound, because it is pressure gradient change, there is need for air movement at "wind speeds". When you press your bellows with air button pressed, you aren't struck by a sonic boom, just a mild wind blow. This is this "wind speed air movement" which starts reed oscilation by a transfer of momentum between air molecules and reed tongue and suction effect of the gap and then feeds reed resonance for a stable oscilation and nice concertina sound.

You could also try this: http://www.plastidip.comin it's liquid (not spray) form. It creates a thick, elastic, rubbery paintcoat, that should dampen the vibrations well and you won't risk greasing everything inside your concertina, but I'm not shure how thin coat you can achieve with this, as I have used it only in completely unrelated project.

Beside the reeds themselves, the most time consuming parts of the concertina (and hardest to do in an amateur workshop) are levers and buttons - even some proffesionals outsorce lever making to a laser cutting workshop. From my experience, any wooden part can be home made with satisfactory quality and tolerances with reasonably cheap equipment and enough patience. But metal working requires heavier equipment, heat generation handling, better tools with tighter tolerances which are usually more expensive etc… And don't forget, that there are dozens of levers and buttons in a concertina, and those sheer numbers make making them very time consuming. My 66 buttons took me the same amount of time, as the whole endboxes and reedpans (without the fretwork cutting, which is another time consuming part, but depends heavily on fretwork design and material used).

It is not the reeds that rattle, but the unbushed buttons of your Jackie. And this was so annoying for me after purchase of my Elise, that I have modified it within two weeks of delivery… Unfortunately there is not much you can do about it except for entirely replacing the buttons. The problem is caused by those thin and light metal strips that form the base of the buttons, which tend to vibrate on the levers due to air vibration and rattle on the levers. This is a big design flaw of concertina-connection entry level instruments, strangely happens only to some batches of those instruments or only some of buyers find it annoying. But it is definately button-related, as it has vanished completely after button replacement. [A quick edit] What you could try to do besides replacing buttons is to cover the end part of levers with some sort of silicone paint - a layer thin enough to easily go through a hole in button posts, but thick enough to dampen some of the vibration. Or you could try to bush only endplate holes with a thin felt, but this may require redrilling the holes to a bit larger diameter - the felt bushing holds buttons a bit and this may be enough to dampen any unwanted vibration.

By "static" I don't mean stationary, but "equalized at all times" - in this case, in your approach, high pressure is always compensated by internal spring force. It does not mean that the tongue does not bend, only that forces are equalised in any given "time slice". I may use the wrong english word to describe it. "Dynamic" in my comments mean that the process does not equalize in such manner, and there is no such "missing force" in any given "time slice", but you have to consider the whole temporal evolution of a system consisting of high pressure reservoire, tongue spring, gap suction, airflow etc... The reed is not a physical pendulum, it is a spring oscilator. The "missing forces" (if we must name it as such) that you choose to neglect are dynamic effects of gap suction, initial airflow increase, pressure gradient "momentum" and resonant oscilation effects in the first cycles of the reed movement and I have given you a very extensive and detailed description of that process. And I'm not debating on how the reed work, I'm refering to you a well established knowledge, which for some reason you refuse to acknowledge… And you have even mentioned earier, that you have read an extensive essay on the matter on concertina-connection site, but you still refuse to agree, that symmetrical or flat reed simply won't work... So I have one question for you: Your description does not differentiate sides and you assume that flat reed would work. In your model, what is the difference between the physics of sounding and silent direction of airflow through traditional reed? If there is none, and gap and asymetric thickness is irrelevant and flat reed should work, then why the reed sounds only in one direction and flat reed does not speak at all?

Then it is not correct, as the gap and asymetry are crucial in free-reed, accordion/concertina like instruments which is proven by almost 200 years of experimentation and you can replicate this in a 1 minute experiment involving a single reed and pair of lungs… You are describing a spring pressure valve here, not a free reed oscilator. What you are (correctly) describing here is the physical process involved in a static tongue bending caused by pressure gradient and air leaking through an unvalved reed in it's silent direction, until all bellows is compressed and there is no more higher pressure reservoire. At which point (and just then) the net force you describe is in fact accelerating the tongue back to it's resting position with some tiny amount of oscilation at the end of it's movement. The process involved in producing sound by a free reed is entirely different, involves a gap and asymetry of the reed, and I have described it earlier. If you don't see your mistake at this point I have no more ideas on how to point it out to you... You're welcome

Reeds from Wim have (at least had few years back, when I wrote to him about it) separate waiting list of a few weeks only. But they do cost more than a half of a finished Wakker concertina... One other thing - why we assume, that exchangeable reedpans mean "two reedpans with a full set of reeds each"? If we just want a non-destructive conversion it can be perfectly done with a single set of reeds that covers both layouts and two sets of wooden parts. There will be of course need for tuning after each conversion, and some form of "placeholder reeds" for keeping reedpan dimensions stable, but I really cannot imagine, that one would want to swap reedpans on regular basis, as even with separate reed sets it takes too much time to swap "on the fly" at a gig. And personally I don't understand a need for playing two different duet systems, other than different sound or range of available instruments, which makes such "dilution of practice hours" a necessity.

Sory, you have mislead me into believieng you have it backwards by this sentence: "As i understand it, the slight bend in the reed (toward the lower pressure side) allows air to flow around the end." as it is exactly oposite to reality. Because it does not work like you describe… A reed without a gap does not speak, flat reed mounted perpendicular does not speak. Perpendicular reed needs to be assymetric and require a gap and nothing can be done about it. It is just how reed physics works. Please make a simple experiment - take one of your bass reeds, bend it back flat into the shoe so there is no gap and try to make a sound. It won't speak at all and will be just poor pressure valve. [bass one is best for this purpose, because high tone reeds require only a slight gap to start, so even when flatted out, the tolerance around the tongue is a gap sufficient to start the movement at low pressure levels] This is the point where you get this wrong - as long as you have pressure it won't accelerate back, it will just stop bending more and will find stable bent position depending on the pressure gradient. In more elaborate form: in the flat, gap-less reed the pressure is just released as through valve - spring just bends proportionally to the pressure pushing on it [and because tongue thickness is so small it happens with very minute pressure gradient levels]. As long as you squeeze your bellows with same force, the pressure inside is constant, the reed/valve opens and air just flow outside with a rate depending on reed stifness. This is exactly what happens when you blow air through reed in oposite direction - it just leaks air, it does not oscilate and in this case the initial gap seting is irrelevant (it can even be "negative", i.e you could set the tongue to be initially inside a shoe, this will just slightly increase "releasing pressure"). Of course there is some oscilation when you release the force on the bellows, but this is not resonant oscilation, just a depleting momentum of an elastic valve returning to equilibrium, making no audible sound at all. One other thing: pressure gradient changes are not instantaneous. When you press your bellows or open the pad on the airhole it takes some small amount of time to start the airflow. This is the moment when reed oscilation "jump starts" through gap mechanism on pressure levels lower than needed for stable oscilation, so when that pressure is achieved the reed is already in it's swinging motion (the gap is a leak which makes effective pressure gradient lower at the start of the motion than when the tongue is inside the shoe and blocks the airflow). With fast enough, high pressure pump instantly and constantly feeding high pressure air through a reed you can choke even the properly set assimetric concertina reed and effectively turn it into a mute pressure valve. This is one of the reasons why different free-reed instruments require different reeds depending on operating pressure levels, as this can even occure on my Elise lowest bass note, when I squeeze a bellows the hardest I can, as it has accordion reeds, designed for lower pressure levels.

Don, there are both vintage and modern traditionally reeded concertinas with shoes mounted this way. Here you have Steve picturing his Wheatstone in my DIY thread: http://www.concertina.net/forums/index.php?showtopic=15371 And here you have Lachenal bass concertina: http://www.concertinamuseum.com/CM00292.htm

You think it backwards… Reed tongues are bent to the higher pressure side: pressure is working towards closing the reed (pushes the tongue inside the shoe, not away from) and is released when tongue reaches the other side of the shoe. Then the energy acumulated in the tongue swings tongue back against the airflow and opens the reed for half a cycle, when another portion of air draws the tongue back into the shoe with more force. And this initial gap works as a miniature version of a bladeless fan - it is essential to draw the tongue into the slot with initial pressure lower than needed to hold the tongue on the other side permanently. It is dynamic not static process and takes a few cycles to achieve resonant and stable vibration. Without this gap (and in the oposite direction) a reed tongue works as a pressure valve which won't vibrate - it will just open in a static way when pressure gradient is high enough to bend it and let the air out from the higher pressure reservoire. There are asian type free reeds, which are flat as the one you describe, but they work on a different principle and need a pipe resonator to sound and are mounted parallel to the airflow direction, not perpendicular as in concertinas or accordions.

Don't get me wrong, I was not intending to insult you or Jake in any way. In fact, I had some similiar thoughts about "pneumatically improving" concertina design when I first started designing my DIY Hayden. That was until I made this very experiment I have described earlier and realised, that sound produced by the reed is a very fragile thing and everything affects it, usually in the least desirable way. There are numerous long threads here on concertina.net about such minute changes to instrumenst as beveling airholes on chambers that are placed not on the edge of the reedpan or have additional 5mm of action board "in the way"of the sound. My "seem to forget" coment was only meant to point out, that concertina design should be s"ound-centric" and not "pneumatic-centric" and that many (otherwise great or intiguing) engeneering ideas simply do not apply to concertinas.

This one is more true with hybrid concertinas and accordion reeds, but applies to a proper concertina reeded instrument also - you have to place your pad assembly out of the way of swinging reed and inner reed valve. Normally you can have your air hole directly above the reed (flat mounted accordion reeds have chambers rougly the lenght of a reed shoe, concertina reeds chambers can be and often are extended for acoustic reasons). In your design you have to place the button assembly "out of the way" - you cannot place your pad and spring over the reed. In my opinion, both yours and Jake's designs are valid only from a pneumatical point of view. They will both produce controlled pressure and airflow to feed the reed. But both of you seem to forget, that it is the musical instrument that you're working on. Every bounce of sound matters, every cubic inch of confined space that vibrating air has to travel inside a concertina will alter the sound. Make a simple experiment: build a variable volume reed chamber (a moveable one side, like a piston), apply airflow through a reed mounted to it and listen to the sound while moving a piston. And measure response time of the reed depending on volume (cubic space not loudness ). Then put a tube (either straight or bent like in Jakes design) on the airhole and listen how sound produced by such setup changes drastically - depending on materials used the sound would be more or less muffled and altered in timbre. In Jake's design the amount of distance that the air has to travel inside a tube will decrease the loudness significantly, and the reeds will be very slow to speak because the sheer amount of air trapped between stationary reed and button, that needs to be moved/compressed before the reed starts to speak…

There are so many problems with this design I can think of, that I don't even know where to start... First of all, such design seems valid only for linear keyboards, as you cannot freely move airholes around and you have quite space-demanding design... Then, your reed chambers would be HUGE, as you must effectively make them longer by a diameter of your air hole. Otherwise your pad will obstruct inner reed valve. This raises a numerous problems with reed response times and tone balance, as you will have to increase each chamber lenght by a fixed amount, thus for smaller reeds probably doubling the chamber lenght… And you create a LOT of unwanted bouncing of sound and obstruct chamber resonance properties with this "inner pad". And resulting sound will probably change substantially with button travel, as you're moving parts inside of a resonant chamber... Another problem with this design is a small effective airhole: with normal setup, you need only short pad travel, because you have a cylindrical gap between airhole and pad (in open position you need a height of quater of hole diameter to have equal flow areas). With this design you obstruct a lot of this cylinder with back and side walls of a chamber. Try to imagine a smoke traveling through reed and airhole in this setup to visualise what I'm thinking about. Last problem I can think of is the wobblines of this setup - in normal concertina construction, you have two guiding constraints for a button: an endplate hole and an actionboard hole. Together they make button motion almost linear. But with your design you only have endplate guide and a wobbly spring. You will have to either add an inner pole to guide a button and pad assembly or find another way to ensure perfect closing of airhole (like conical hole closure for example) and limit angular deviation from straight button travel.

First of all, warmest welcome to another Hayden player! And now to the point... Chords on a Hayden duet and corresponding music theory is much easier than on non-isomorphic instruments. Virtually everything you should know to play chords on a Hayden is shown here: http://www.shiverware.com/musix/wicki/chords.html Those are chord diagrams on this keyboard. Since it is isomorphic, all chord types in every key have a single "shape". You must only know the root note and type of chord you want to play and that's it. You can READ the chord structure from the keyboard itself, so there is no point in chord wheels or similiar detailed chord charts… And when you'll learn chord types in your finger memory, it becomes natural to make your own accompaniments and countermelodies, as you'll be able to read harmony structure of a tune straight from melody line. Regardless of key, since the concept of a key on a Hayden is somewhat artificial and obsolete...

Absolutely beautiful playing and a great tribute for the passed away...