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Everything posted by ttonon

  1. Hi John, Like you, I’ve had many interesting experiences with Asian instruments, and hearing them has opened my mind on how I think about musical instruments, their functions, and in fact, my whole concept of what music is. I have no doubt that you can detect the sound of a concertina reed in the sound of the Sheng. You see, all kinds of musical instruments have their complexity, and no simplified view can ever include all there is. There are many Asian free reed instruments, and all have defining characteristics, some with very varied tones. The Sheng (China), Sho (Japan), and Khaen (Thailand and Laos) are similar in that they contain one free reed per tube resonator, with each single instrument having many resonators. Thus, each reed plays only one note, but the entire instrument can play more than one simultaneously. Other instruments, such as the Chinese Bawu, have one reed mounted in a tube resonator that has finger holes, just like those in a flute, and a single reed plays many notes (eight in the case of the Bawu), but only one at a time. But there are differences within these groups. In the Sheng, the reed is tuned so that it’s (first mode) natural frequency is close to that of the tube, whereas with the Khaen, the tube frequency dominates, pulling up the reed vibration two, three, maybe more, times its own frequency. And of course with the Bawu, the tube frequency dominates, because that is the means of producing different tones. The shape of the reed tongue of the Bawu also differs. With the single note variety, the tongue is more or less rectangular (in plan view), whereas with the Bawu, the tongue is triangular, which probably explains a great deal about why it's so willing to yield to the tube on how fast to vibrate. I say all this only to give an idea about the many parameters the Asian builders have discovered in order, like their Western counterparts, to tweak out the sound they want, and different cultures have found different sounds. In fact, taken as groups, the Asian free reeds allow for a much wider spectrum of tonal variation than do the Western free reed instruments. This is not surprising, since the Asians have two major components to work with – the reed and the resonator – whereas the Westerners have only one. In my previous post, I presented the spectrum of the Bawu as an existence proof, illustrating that, when coupled to a tube resonator, the free reed can sound much differently from the Western version (and from some other Asian versions), perhaps sounding more like the tube resonator than the reed itself. The Asian free reed, in fact, has very little sound without a resonator, if any. (It operates as a “blown open” reed, whereas the Western version acts as a “blown closed” reed.) Thus, it’s not surprising that the sound of the resonator can have a dominant effect. One complication worth mentioning with the example you chose – the Sheng – is that musicians often play it with one or two reeds sounding continuously, as a drone, and perhaps such operation might make it easier to identify the Western free reed in the sound, because then, the spectrum becomes richer. The following links might help you get an idea of how the Bawu sounds: Yes, I think it’s true that Western free reeds do not operate “in unison with a resonator,” as acknowledged in the scientific literature. Perhaps a key term here is “in unison.” The Asian free reeds do operate thusly, containing an acoustically coupled system, with the result that the air column and the reed tongue vibrate at the same frequency, which is generally a little higher than the first mode (and sometimes second mode) frequency of the tube resonator, and which can be very much above that of the reed itself. It’s interesting that the Western beating reed wind instruments – also coupled systems – operate at frequencies far below the natural frequencies of the reeds. But “not operating in unison” does not mean that the sound of the Western free reed is not altered by the cavity and associated structures near the reed. Compared to the overall excitation of the vibrating tongue, however, these effects are too small to define a coupled system. For example, the difference in frequency between the unmounted Western reed tongue frequency and the mounted frequency is typically, I believe, a dozen or so cents, and I’m willing to be corrected on that. This, however, is not an example of operating “in unison.” I'm also under the impression that Western builders do not want vibration in the wood mounting parts holding the reed. I see physical reasoning for this: so that energy is not sapped from the reed itself. Thus, Western instruments are designed to avoid acoustic coupling with the body of the instrument. The string instruments are somewhere between the free reeds and the Asian reeds, though I don’t think it’s correct to view the string as “directly coupled” to the wood. The function of the wood is more or less only in one direction. It taps off energy from the vibrating string, but it does little to influence the string vibration. It provides a mechanism by which the string can be made to work hard at getting sound energy into the air, without which, the string vibration would be essentially inaudible. A measure of these statements is the fact that the strings vibrate at very near their own, independent natural frequency, which is often way below the natural frequencies of the wood. One complication is with the violin and similar instruments with a hole in a body that contains an air volume. With these, there’s a Helmholtz vibration of the air within the body of the instrument, and this also serves an important function. But again, this is not coupled vibration. The string dominates, dictating the frequency at which the wood and air vibrate, with very little backward influence. If a natural frequency of any part of the body is excited, the result can be good, as with the increase in volume of those frequencies close to the Helmholtz frequency, or bad, as in the case of the generation of the “Wolf Tone” in violins, cellos, and similar instruments. The Wolf Tone is what happens when the string gets anywhere near vibrating “in unison” with the body of the instrument. You don’t want Wolf Tones, and so, you don't want operation with significant feedback, or, "in unison." Best regards, Tom
  2. Hi Dana, It’s very nice to hear from you again. Good intuition, and I have similar suspicions. When the cross section varies, additional terms are added to the governing equation, and the effects of these extra terms can be broken down into two parts: 1) the effect of the material, and 2) the effect of a changing cross section. The material effect is the easier one, simply because the material is the same throughout the tongue length, and putting your intuition in mathematical terms, it enables you to factor out the ratio Y/rho from all those additional terms. Thus, the effect of material, is basically the same, and it’s confined to the simple ratio, Y/rho. The additional terms involve S, the cross sectional area, and k, its moment of inertia. I myself am not familiar how much k and S change in typical reed tongues, but if the changes are not too great, the problem is amenable to the technique of small perturbations, and indeed, this problem has been partly solved in some instances and completely solved in others, as appearing Morse, Vibration and Sound. Thus, there’s a lot more future work that can be done with this problem, and when I get time, I’ll pursue it and report back. But at this point, I think it’s safe to say that an x percent total change in either S or k^2 will produce about an x percent change in the results, provided that x is confined to about 10 or so, and less. Very good observation. As I mentioned, predicting the sound of the reed is most difficult, and theory so far is incomplete in this regard. But we can certainly speculate, based on our intuition. Let’s take the simplest case. We then are concerned mainly with the effect of air on tongue motion, and its reverse, tongue on air motion. Two tongues of different lengths, but with the same Reed Number (RN), will vibrate with the same frequency and shape, as scaled to its length. This means that the larger tongue will have to experience higher velocities, because its tip experiences larger amplitude. It’s accelerations must likewise be larger, which leads us to conclude that the longer tongue will impart more force in moving the air out of the way. Hence the larger tongue should experience more volume for two reasons: larger pressure pulses and more area to generate sound with. Thus, as you suggest, it would be helpful to be able to quantify the relationship between tongue length and overall sound power. Although it might not be very easy to calculate this from theory, there’s hope that empirical relationships can be found. The scaling relationships I presented can be perhaps a part of the decision process involved with balancing reeds. For instance, if changing the tongue length is desirable because of frequency considerations, but such change will probably produce an imbalance in volume, then perhaps a change in thickness would be a better way to address the frequency issue. Best regards, Tom
  3. Greetings, I started this topic in another forum, and there’s a bit more to say on it, though I’ve moved it here to where its subject matter is more appropriate. As with Pistachio Dreamer, along with the image that moniker stirs up, there’s sometimes the issue of matching the properties of reeds having different tongue materials. As I mentioned in the other post, the problem of the vibrating cantilever has been solved in the simplest case; i.e., freely, with no air resistance, and wherein the beam has constant cross section. It may be useful to extract from this formulation as much as we can, as a way to make practical comparisons between reeds with different materials and geometries. The attached pdf file gives four equations that may be of some interest. The first numbered equation gives the vibrational frequency of the first mode of vibration. The next three allow the calculation of a parameter for reed 2, given the same parameter from reed 1, which differs from 2 in its length, thickness, and material composition. I should describe a bit where these four equations came from. The first falls out of the solution of the governing partial differential equation of motion. The next three originate not by solving this equation, but by simply nondimensionalizing it. Nondimensionalization of equations is a common trick among engineers and mathematicians as a way to understand these equations, and in particular, the method allows a comparison of the relative magnitudes of the various terms. In some applications, some terms are very much larger than other terms, in which case, the smaller terms can be simply thrown away, at least to some specified level of accuracy. Such an approach is fundamental to acoustics and other forms of “small perturbations.” Thus, I nondimensionalized the basic equation, using the reed’s length as characteristic length, and the period of oscillation as characteristic time. As usual, the process spits out a nondimensional group, or combination of parameters, and characteristically, such a term can teach a lot about the behavior of the solution – without even performing the solution. I call this group, for want of a better name, the “Reed Number,” RN, as shown in the attached file to be a grouping of frequency, Young's Modulus, material density, tongue length, and tongue thickness. Okay, perhaps I’m getting into too much abstruse material here, but before I stop, I should really present when such results are expected to be accurate. By nondimensionalizing with respect to the tongue length, as opposed to, say, the wavelength of oscillation, the convenient result is that the equation describes the position of the tongue, all along its length, as a fraction of its length. Thus, if two different reeds – different frequency, material, length, and (constant) thickness – have the same RN, their vibrational shape will be identical. Yes, one reed will be longer than the other, but the difference is only scale - no more than looking at a given reed under different magnifications (we are not concerned in the simplest case here the width of the tongue). As mentioned, the above reasoning applies strictly to the simplest case; i.e., no air resistance and constant cross section. Real free reeds do experience air resistance, taper (change of width along the axis), profile (varying thickness), and slots beveled in different ways. However, what are the magnitudes of these complicating features? In general, concertina reeds have little taper, and I don’t expect too many problems there. It’s also my guess that the air resistance, even as influenced by the different slot angles, is relatively small. Yes, I understand that these things affect sound, but our first concern here is frequency and its sensitivity to material properties and geometry. I think the most serious deviation from the simplest case arises in tongues that have a large amount of profiling: appreciable modification in thickness along their axis. How well the scaling parameter RN can account for real effects can only be determined from experiment. In some cases, the tongues in question might conform very closely to the simplest geometry, and in other cases, perhaps the profiling of two different reeds might be purposely made to be the same, and in still other cases, this approach might only provide an initial guess, and hopefully, subsequent necessary modification of profile might be minimized. The simplest problems, and ones for which the most (relative) accuracy should be expected, involve calculations of frequency. Solutions that seek to produce the same sound between two different reeds are more difficult and require more accuracy, perhaps in some cases beyond what this approach can provide. The proper approach would thus appear to be: use the equations as a way to work among the parameters f, a, L, Y, and rho. These equations, however, can give no guarantee about the sound, a property that is subject to the subtlest of parameter variation, and for that, we need experimental confirmation. I would be interested in hearing feedback from those experienced in making reeds, especially reeds of different tongue materials. There are also perhaps already rules of thumb that are used in order to accomplish what I’m suggesting here. If so, I’d be curious to know how well they agree/disagree with this proposed approach. Best regards, Tom www.bluesbox.biz Free Reed Scaling.pdf
  4. Not quite the same thing. A pianist can use his hands and arms, while a concertinist can only use his fingers. That's a good point, and it must have some influence on dexterity. In fact, a professional classical pianist I know said that it's his arms that really do the playing. At least this is how he approaches it from his mental perspective. But there's still a detail here wherein the entire force against the key is experienced by the fingers, being transmitted then to the hands. If the keys were pressed by vertically coming down on them with the fingers perpendicular to the keyboard, then the finger muscles would play little role, and the force will be transmitted to the hand through compression of the bone and cartilage. But that's impossible, and finger muscles, with varying degrees of mechanical advantage, are the first line of action on the keys. Tom
  5. Hi Wim, Thanks for your comprehensive and lucid explanation of the many features and considerations behind the design of the tone generators in a well thought out free reed instrument. I wish you continued success in your endeavors. Best regards, Tom
  6. Hi Michael, While I myself tend towards innovation, I also sympathize with the traditional player who has devoted many hours to learning a genre that has a well established musical tradition. It sometimes takes years to be able to identify just what that sound is, and how to incorporate it into your playing. Since every instrument has their identifiable characteristics, it’s not surprising that the instrument becomes identified with the genre, and in general, it’s thus very difficult for an instrument foreign to the genre to fit in. When accomplished players experience such an attempt, it’s not too surprising that they might conclude that their musical credentials are being cheapened by amateurish ramblings they’ve worked years at eliminating, from their own playing, and from the playing of others they choose to jam with. At the same time, unexpected outcomes are always possible, provided they be given some kind of fertile ground, and there are many accomplished traditional musicians with a more open mind on the matter. They practice tolerance, though I suppose it has limits. Perhaps it's these latter folks that most facilitate the evolution of a genre. In the US, there are relatively few accomplished accordion players outside a few specific genres, and I’ve seen clashes when such well meaning players try to join in with experienced, accomplished musicians in traditional realms. I myself play piano accordion and single row (Cajun) style accordions. I’d never think to bring the PA to a Cajun jam, but for me at least, I can sometimes use the PA for zydeco, or blues, wherein this instrument has a strong tradition. I also delve into a bit of Old Time with the PA, but primarily by my lonesome, for the simple reason I know I’m not good enough in the genre to not irritate the other players. In spite of this, I do have hopes that I can improve enough and be able to play in at least some capacity with the more open-minded members of the genre. I’ve had some good experience using the PA in a few Bluegrass jams, and there, I think I came off as accomplished enough, at least in the tunes I knew well. The different sound from the instrument piqued the curiosity of others, perhaps because they never heard the instrument played quite in the same way. I think such experiences as those, with all the joy, curiosity and sharing, are relatively rare. Best regards, Tom www.bluesbox.biz
  7. Hi Wim, I may not have been clear enough in my first post, and a picture should help. If you look at the attached doc file, you will see the sound spectrum of the following: an accordion reed, your Parnassus, a trumpet, a clarinet, and a bawu. The spectra clearly illustrate that the number of dominant overtones present in the sound spectra of Western free reed instruments is considerably larger than that for other reed instruments. This is the fact that I referred to as unalterable – the relatively high number of overtones. I didn’t mean to imply that the relative amplitudes of these overtones cannot be altered, to some extent, by design. The inherent reason for such a plethora of overtones is the fact that the reed tongue vibrates at its fundamental frequency, which is periodic, creating periodic air pulses, and with such a violent process, the pressure pulses contain large derivatives (changes) in time. (There can be contributions from the tongue’s second mode of vibration, but these have been measured to be very small, even at above normal air pressures.) My reason for stating that “the relatively high number of overtones are unavoidable” follows from mathematics, the language of Physics, as expressed by the Fourier Theorem, which states that any (continuous) periodic function can be represented (over a finite range) by an infinite number of functions, each periodic in time. Our ears, in their remarkable way, are able to interpret such a result. The other instruments I refer to, however, are not bound by this kind of Physics. Their tone generators operate on different principles, and their spectrums reflect that fact. Your explanation was occupied with, in effect, the relative amplitudes among this vast number of overtones, and that they have been altered by design, and I have no objection to that. I can understand that you, as a concertina maker, would be very concerned with such detail, but my comments were from the much larger perspective of all instruments. In other words, no matter how successful you may be in altering the sound of the (Western) free reed, you cannot avoid the fact that its sound will be comprised of quite a large number of overtones, in comparison to most other instruments. There are other instruments that share this feature, but of course, such instruments also have different key features. Similarly with the start transient: I understand that designers/builders/repairers have some control over such a feature, but again, no matter how many tricks you use to alter such a feature, the musical effect of the start transient will never compare to that of, for instance, the piano, guitar, or xylophone. Perhaps what I’m saying here is that none of the design detail you describe can make a concertina sound different from a concertina. But the Asian free reeds do accomplish such a feat. As the spectrum in the attached file shows, these instruments behave quite differently from the Western free reed instruments. The reason for this is that the tone generator is not solely the free reed, but rather the reed operating in unison with a resonator. Here, we have a fundamental change that goes far beyond any changes you can effect by concertina design. Your comments concerning “volume balance” were well taken, and I read them with interest. I had omitted such an issue, not considering it really basic to the free reed. However, if builders can indeed render such an issue negligible, then I suppose we should consider such and issue not to be fundamentally inherent to the free reed, in which case, we might relegate it to good design practice. Still in all, I wish you had included more detail on what design features you think are important here, but I understand that such information may be proprietary. Your comments on “voicing reeds” also seemed interesting, and I can imagine some theoretical basis for it. I hope you understand, however, that without a presentation of data, I’m left with very little concerning how importantly I should regard such comments. Though again, I completely understand why you would not want to do that. On the other hand, the results I hear on the Youtube video appear very good, and I must take note of that. I do detect a rather good separation of sound between the lower and higher registers. I think, however, that distinction between notes in the same register reflect very well the nature of the free reed tone generator. Yes, here, we are in complete agreement, and perhaps my long-winded reply here is not really necessary. This, I find odd, and a bit surprising. Usually, when manufacturers claim to have made an improvement in something, they are very eager to show proof of it. I understand your reluctance to share design secrets, but not to share data. After all, a video on Youtube is, in a sense, sharing results, no more than sharing data would be. If you showed convincing data, I would be more impressed than I am from the video, and without the data, there remain questions. But to be fair to you, there will always be questions. Wim, I don’t understand why you use so many undefined terms and jargon in your technical explanations. I’m probably at the opposite end of the spectrum from you, in this regard. Sometimes, I have no idea what you're talking about and think that you must realize that. It’s not that I’m incapable of understanding any of the technical aspects of this subject matter, and you do seem willing to spend considerable time in your explanations. It’s thus a shame that your efforts cannot go very far, at least with me, a person who genuinely wants to understand what you have to say. Some of the terms you use appear scientific, such as “Bernoulli,” “reflection,” “acceleration,” etc., but there’s no science in your use of these terms. Maybe you don’t think I would be interested in all the detail. I am. Best regards, Tom Compare Free Reed Spectrum.doc
  8. Hi Wim, thanks for the video of your very accomplished performance in, what seems to me, a difficult musical genre. I believe the tonal spectrum of the free reed, throughout its musical range, is due to the presence of a relatively very large number of overtones (often, dozens), which are perfect harmonics, and I agree that this feature is unique among musical instruments. Fundamentally, it arises because the tone is generated as a result of periodically chopped air pulses, which, according to the laws of Physics, must result in such a sound spectrum, and reed design cannot alter this fact. However, perhaps as you describe, it can be minimized in some way. Another key feature of the free reed is its relatively slow and gentle start transient, during build up to the steady, periodic tone. Such a gentle start transient can be contrasted with what we have, for instance, in percussively-started instruments, such as the piano, and in plucked instruments such as the guitar. The start transient is also fundamental to the tone generator and not very amenable to alteration. Within a free reed musical performance, it’s my view that both these features make it much more difficult for individual tones to be distinguished from others, if we are to compare the outcome with that from most all other musical instruments. Perhaps the closest approach to a similar result is achieved with the bowed string instruments. Thus, individual notes of the free reed within a chord, or new notes that appear during the sounding of others, do not stand out, as much as with other instruments. These other instruments not only enjoy an advantage in the very nature of their spectrum, but also, as you describe, in the fact that this spectrum changes within the musical range of the instrument. To better understand the issue here with the perfect harmonic, overtone-laden spectrum of the free reed, in the simplest case, consider two notes an octave apart. The overtones of one note (save for the fundamental of the lower note) are completely and exactly contained in the spectrum of the other. With the piano, whose tone is a transient and not a sustained periodic wave form, the “stretched harmonics,” due to rigidity in the strings, cause upper overtones to differ slightly from perfect harmonics, changing the spectral characteristics of each note, and thus, our ears can more easily perceive a difference in their tones. You might say that the “noise” inherent in the tone of the piano benefits the musical outcome, and in some sense, the piano is something like a well-tuned bell. There are other interesting features of the piano tone that would contribute to my efforts here, but these would carry us far astray. With the brass instruments, and to some extent, the blown reed instruments (woodwinds), both of which have far fewer overtones (sometimes only a couple), different notes octaves apart do not comprise the same spectrum, and upper register notes can much more easily be distinguished from lower notes. Especially, as you describe, when these upper notes have characteristically different spectrums (reasons for which we cannot delve into here). Furthermore, the nonlinear interaction between the (beating) reeds of these instruments and the inherent, resonating air column also add complexities to the sound that help us distinguish among different, simultaneously-played notes. As far as I know, there are no nonlinear effects with the free reeds than can be exploited in order to likewise shake up its sound spectrum. The subtle start transient of the free reeds seems to allow new notes to appear among other played notes almost secretly, perhaps sometimes even without our awareness. With the piano and other stringed instruments that are plucked, however, our ears take advantage of their sudden, louder start transient, which prominently announces the start of each new tone. An interesting example here is the Hammond electric organ, which was purposely designed to have a prominent, percussive-like, start transient, and which has given the instrument a decided advantage over the free reeds in the jazz genre of music. I thus commend you on focusing on such an important aspect of concertina tone, and for making efforts to improve on it. The builder doesn’t have much room to maneuver here, being confined to the secondary tonal effects of the cavity and other acoustic structures near the tone generator. I’m curious if you’ve made acoustic measurements on the instrument throughout its range and whether you’ve studied its quantified frequency spectrum. If so, could you describe what changes you believe your design has produced in this spectrum, and whether these changes proceed in any consistent way throughout the range of the instrument? Even further, if you’re inclined, can you talk a little about the actual changes in design that you’ve made? I understand completely any reluctance to do so, seeing such information as possibly proprietary. In any event, I wish you well with your efforts, as designer, builder and performer extraordinaire. Best regards, Tom www.bluesbox.biz
  9. As most of us realize, the sound from a free reed arises from the chopping of air by a vibrating reed tongue, called a “bar” to acousticians. We can thus divide the subject into two parts: 1) the vibration of the bar, and 2) the aerodynamic response of the air stream that interacts with the vibrating bar. The problem of the vibrating bar has been solved many years ago. The simplest case is the one where the bar is of uniform (constant) cross section (constant profile and not tapered), and this solution is completely defined by the material properties of the bar and its geometry. We are talking here solely of longitudinal vibration, excluding any torsional vibration. The material properties appear in the solutions only through the ratio of the Young’s Modulus to density (Y/rho), and the geometry appears only through the bar’s thickness and length (it’s width doesn’t matter). Thus, two different bars of the same thickness and length, but with different materials that have however the same ratio of Y/rho will vibrate in precisely the same way. Although this conclusion strictly applies to uniform bars, my guess is that – and I haven’t verified it -, for the same geometry (same thickness, length, taper and profile), the only material input to the vibrational behavior of a reed tongue is the ratio Y/rho. (My hunch here is whetted only from a recent glance at the derivation of the governing partial differential equation of motion for the uniform case.) When we consider the aerodynamic effect on the air stream, I think it’s reasonable to say that, if two reed tongues are governed by the same equation of motion – as they would be, with the same Y/rho -, their aerodynamic effect on the air stream is probably the same. So the entire issue, when comparing the sound made by reed tongues of different material, (I believe) comes down to what difference there is in their ratios of Young’s Modulus to density (Y/rho). I agree that such a conclusion doesn’t answer all the questions that arise here, particularly with regard to whether some materials will produce “better sounding” reeds than other materials. But maybe we can eek something out here. I should mention first that a complication that arises here is that, to produce the same frequency of vibration, two different materials having different Y/rho will require different geometry (particularly thickness). There is thus a cross effect from material properties to geometry, concerning the effect of a given material on reed tongue vibration, and presumably, this cross effect will also carry over into the sound. But the results I present here can shed some light on questions such as, would a plastic reed tongue sound the same as a wooden reed tongue, or a metal reed tongue? The answer is that, if the ratio of Y/rho differs among these materials, then it’s reasonable to expect that their resulting sounds will differ, unless some miraculous happenstance occurs. But feeling adventurous, we might venture a corollary, such as, the closer the ratio of Y/rho is between two materials, then the closer will their resulting sounds be. That is, even though there is a cross effect between Y/rho and geometry, it might very well be that this effect does not completely destroy such a corollary. Let’s take some examples. We can look up material properties for the following materials: Spring Steel, Series 300 (Austenitic) Stainless Steel, Series 400 (Martensitic) Stainless Steel, type 467 Brass, and Polycarbonate plastic. From Matweb, I chose values at the higher range for Young’s Modulus and density, which is more constant, for these types of materials, with the results for Y/rho as follows, having units 10^10 x (in/sec)^2: Spring Steel, 4.15; 300 series SS, 4.19, 400 series SS, 6.24; 467 Brass, 1.84; Polycarbonate, 0.413. The results are interesting. I have no idea what kind of Stainless Steel makes up the reed tongues of Paul’s concertina, but the above results do substantiate the possibility that traditional Spring Steel tongues and some kind of Stainless Steels can produce similar sounds. Also from the above, some kinds of Stainless Steel can sound different. The Brass alloy I chose, 467, is a phosphor alloy Brass, which is relatively very resistant to corrosion, and I picked a high hardness (so that work hardening during operation is minimized). I have no idea what kind of brass was used in Concertinas in the past. Let’s have a little more fun here. The general consensus I believe is that “Brass reed tongues sound more mellow than Spring Steel reed tongues.” Okay, if that’s the case, looking at the trend in how the ratio Y/rho changes among these materials, we might guess that Stainless Steels in the 400 series might sound more complex, with higher harmonics, than Spring Steel, and that polycarbonate might sound even more mellower or softer than Brass - perhaps too mellow or soft, or too low volume. With all this speculation, we should not lose sight of the fact that it’s important for a reed tongue to be durable and have the ability to hold its tuning. An important property in this respect is the yield strength of the material. Loud volumes may stress the material and cause it to stretch, destroying the set of the tongue. In addition, there are work hardening and fatigue issues to consider. For completeness, the yield strengths of the above materials are, having units of 10^3 psi: Spring Steel, 390; 300 series SS, 260, 400 series SS, 276; 467 Brass, 24.9; Polycarbonate, 10.2. I invite others to go through the materials handbooks and see how the numbers compare, but such investigation should also be accompanied by experimentation, in order to avoid too much theoretical obsession. Best regards, Tom www.bluesbox.biz
  10. In considering the effect of key force on musical performance, it might be helpful to think from the perspective of an accomplished piano player. Piano keys require much more force to play than do concertina keys - especially considering the fact that the piano accommodates dynamic response and the concertina does not. With this in mind, I doubt there's anyone here who would claim that the piano player is somehow more hindered in his/her musical expression or speed. I thus tend to think that personal preference is the largest determining factor on what the right spring pressure ought to be. Regards, Tom
  11. Hi Bertram, I commend you on your entry into Old Time and appreciate the contribution you make. Until I receive your CD, my comments must be limited, but let me start by saying I myself have long felt that there's ample, unexplored territory for bellows-driven free reeds in Old Time. (Many of us are already familiar with the astonishing contributions from harmonica players.) Going only by the samples you provide, I'm surprised at how well the sound of the fiddle and free reed combine, sometimes becoming indistinguishable. In fact, the two sounds themselves are essentially indistinguishable, inside a steady tone, without the start transient. But music is much more than steady tones, and from my own experimentation, the difficult part for the bellows player is the rhythm, wherein there must be complete, instantaneous control of the bellows and exquisite coordination with note selection and de-selection, and with accent. I look forward to hearing the entire CD, when I will be able to get a good feel of the music. I do have one question. Did you have any particular reason for not including traditional rhythm instruments, such as guitar and/or banjo? I myself sense the missing accompaniment, without which the true drive of the music is just not there. Also, I think the rhythm accompaniment would make it, in some sense, easier for the free reed to blend into the genre. You two guys could've ridden on top of the hay wagon with others, instead of walking by your lonesome. But maybe that's precisely the image you went after? In any event, thanks for the music. Best regards, Tom www.bluesbox.biz
  12. Hi Randy, Thanks for the notice. I'm sure many of us here can share with you the ups and downs in finding/losing good musical partners. I hope the future brings for you additional rewarding musical experiences. Is there any way you can share some recordings from this group? Thanks, Tom www.bluesbox.biz
  13. Hi Jody, I just realized that you posted this here. I like your choice of tune and performance. The concertina has an attractive, thin air about it in this tune, and the style of music works well with concertina accompaniment. Thanks for the tune. There's another approach that you also might consider, and that is to play the instrument as a solo instrument, along with other backup instruments. This will be an entirely different animal, as far as concertina playing goes. The need to provide rhythm and lead on the same instrument means that the lead part can be constrained, and it comes out very different from a lead taken as purely ad lib, without such constraints. I'd be curious what that would sound like. In the discussion of the other thread on blues music, comparisons were made with the harmonica. Harmonica blues, however, are primarily - though not always - based on harmonica soloing. For an even further movement in that direction, you can even try miking the concertina very close up to the instrument, but of course, this might also require ramping up the volume level of the whole band. Best regards, Tom
  14. Hi Chris, I'm confused by your explanation of the die stamping. I don't understand how a broach can open up the aperture (slot) more at the bottom than at the top, unless the broach is tapered and moves in a relative upward direction. This would require the broach to stop at a precise axial position. Although not impossible, I haven't heard of a broach being used in such a way, but I'm not an expert on this. The normal broach I'm familiar with that uses one stroke is a stepped cutter, moves in a direction perpendicular to the work piece, and cuts a slot with parallel sides. I also understand that any stamping operation will produce a tapered hole, simply because the punch fits loosely within the die. The loose fit is required so that the punch does not jam, and the softer the metal work, the looser the fit. Thus, the angle of the bevel of the slot, after rough stamping, depends upon the mechanical properties of the plate material. Because of this, I can appreciate Adrian's general point that perhaps the bevel in the slot was originally a manufacturing artifact, which perhaps could've been taken advantage of, as a way to conveniently fit the tongue with precision, since it's only the top side of the slot that then required the most precise shape. I'm really confused here. It's my understanding that a broach cuts metal and does not simply push it out of the way. Perhaps you're describing some kind of operation that molds metal, by deformation? In thinking about all this, another question arises. Have reed makers used a metal working operation that, after rough cutting the slot in the reed plate by stamping, the slot is subsequently shaped to precision by inserting a mandrel, which has the (near) precise slot geometry, and then squeezing the entire plate from the outside, around the mandrel? The mandrel is then removed. With tapered mandrels, this process can conceivably result in a beveled, and/or tapered slot. Your linking a taper on the tongue to a bevel in the slot intrigues me. I understand your basis for this, that both cause a wider air flow passage as the tongue descends through the slot, but this view is entirely a steady state view, and there may be unsteady effects that result in different acoustical behavior. In your earlier post: Doesn't your reasoning cause one to conclude that a bevel in the slot would then more likely affect the sound of the smaller reeds, since, their tongues experience the greater changing air flow in the slot for a greater portion of their period of oscillation? The larger reeds spend less of their time in the slot region, and so are less affected by the changing flow area produced within the slot. This conclusion is not entirely different from my own, which examines basically the relative time portion the oscillating air particles occupy in the region within and near the slot. For the large reeds, air jets are formed, requiring that these air particles move far away from the slot, but for the smaller reeds, air particles vibrate in the vicinity of the slot for much more time, compared to the period of oscillation. Best regards, Tom
  15. Hi Jody, You have piqued my interest, and I'm in great anticipation to hear what you've come up with. Best regards, Tom
  16. Hi Harold, I mostly agree, though we can elaborate. We often run into musical phenomenon that, we all agree, must have a basis in physics, but for various reasons, have never been subject to enough scientific experimentation to establish a widely accepted explanation among acousticians. In such cases, the explanation, or explanations, that win popular support among makers and other interested parties is sometimes the result of a popularity contest. In the case at hand, I wouldn't go so far to say that vent beveling has no discernable acoustic effect, but I think the situation is probably more complicated than often assumed. When this question came up in the forum organized by Chris Ghent several years ago, I presented a physical analysis, based on order-of-magnitude reasoning, from basic fluid dynamics. At that time, as I recall, Dana was finding some useful effect with beveling, though I don't know how far he went with it, as I have been mostly out of contact with this group recently. In that analysis, I suggested that the underlying physics does not rule out some effect, only if the pitch of the reed is sufficiently high. With my rough calculations, I found that, above a frequency of about 1 kHz, there may be some advantageous effect, but for frequencies less than that, my reasoning suggested that there probably wouldn't be. The cut off around 1 kHz is of course not as important as the conclusion that there will be some frequency range, above which the beveling will influence the propagated sound, and below which, the sound produced would have no way of knowing that the beveling even exists. In addition, with the higher pitched reeds, my analysis says nothing on whether beveling can produce an acoustical effect that the human ear can even detect. From a simple point of view, an analogy is to consider the effect of speaker size on the propagated frequencies of the sound spectrum. Small speakers (tweeters) can efficiently send out sound only above a certain frequency range, and for the lower frequencies, they are not very effective. Stepping back to the more general, I have great respect for the makers of musical instruments, but of course, not equally among all makers. If a maker who has impressed me as one who can think critically claims the existence of an acoustical effect, I tend to accept what he/she says, when their claim is based on their own experimenting that such and such a feature has a such and such acoustical effect. When that maker goes beyond simply stating the existence of the acoustical effect and states his/her physical reasonings behind the effect, I feel qualified enough to analyze their explanation in order to see if it jives with my own understanding of fluid dynamics. Such events can then have mixed outcomes. If my analysis leads me to disagree with the physical explanation offered by the maker (or otherwise, by the one believing in the physical effect), my comments are sometimes taken that I don't think there really exists such an acoustical effect, which may not be true. There are important distinctions among 1) the existence of an acoustical effect; 2) the validity of the physical mechanism proposed that produces the effect, and 3) whether the effect can be discerned by a listener with normal hearing ability. In short, concerning beveling of the reed slot, I can very well believe that such a feature has a discernable effect on the higher pitched reeds of the concertina, probably tending to increase volume, and perhaps also increasing the higher harmonics of their resulting sound spectrum. For the lower reeds, however, based on my own physical reasonings, I question that there does exist a discernable acoustic effect: I cannot find a physical basis for it. But I don't make these statements dogmatically, either, for the simple reason that my analysis may have errors. As is normal, such controversies can only be settled through continued experimentation and discussion among a varied group of participants, each with his/her own perspective. Best regards, Tom
  17. Hi Marcus, Hardly. Don't fool yourself. Although both instruments use free reeds, they differ largely, with much musical expression having no overlap. Concerning the blues, the biggest impediment the concertina (and accordion) has is that the musician has very limited, only remote access to the sound source, with a mechanical linkage in between. That is, if you want to play blues like a harmonica player. The piano has a similar limitation, but people work around that and have developed blues style piano playing that emphasizes other, advantageous, features. The keyboard of the concertina can also be made to play adequate blues, but the sound and expression is qualitatively different from that of a harmonica, especially a harmonica miked in the most effective way. One cannot overemphasize the contribution proper miking has made for blues harmonica playing. Even my own invention of the pitch bending accordion does not allow the musician to access the sound source as completely as does a harmonica. But the extra dimension of pitch bending, I think, does propel the instrument much further towards the harmonica in this kind of music. In addition, the keyboard again allows musical expressions that are absent with harmonica, and so, a combination keyboard with pitch bending, I think, brings a genuinely new instrument into the mix. But don't take my word for it. You can hear some "acoustic style" blues on my website, played by yours truly, on the world's first pitch bending accordion. Just click on the link, "Acoustic blues with vocal" on the home page. There are other sound files and videos there that you might also enjoy listening to. I invite you to have a listen and tell me what you think. Best regards, Tom www.bluesbox.biz
  18. Hi Andrew, Thanks for the comments, though I must say that my post really only points out where I disagree with Wim's explanation, and I have not attempted here to give my own complete description of reed operation. But in my PICA article, you can find some other perspectives, if you're interested, the link of which is: http://www.concertina.org/ica/index.php/pica/subject-index/38-articles/87-reed-cavity-design-and-resonance Best regards, Tom
  19. Thanks Greg for the link to Wim’s explanation of how free reeds operate. I read this explanation, liking very much most of it, and in particular, the care with which Wim exercises in explaining details. I would like, however, to make some further clarification, and my comments will perhaps arouse more interest in those who have a more esoteric drive to understand more comprehensively what’s going on, from the perspective of what Physics has to offer. As I say, Wim’s explanation goes far in explaining the state of the art in the overall mechanisms, but from a fluid dynamical point of view, there’s one important omission, and that is the role of dynamics, or what amounts to the same thing, mass inertia. In Wim’s explanation of the “swing cycle” of free reed operation, he includes what he calls “tension energy,” which I gather is a direct translation from another language, and I believe he means what we normally refer to in English as “potential energy,” which is an essential part of the vibration, but what Wim omits is what we call in English, “kinetic energy.” As with all oscillatory behavior, a complete understanding of the phenomenon cannot be achieved without including the interplay between potential and kinetic energies. Thus, the vibration of the reed tongue is just like any other vibration, wherein – to first approximation – total energy is conserved, with continual exchange between potential energy and kinetic energy. Take the motion of a swing. At the highest elevation, when the swing stops, all the energy is potential (in this case, due to gravitational attraction), with zero kinetic energy, and at the lowest elevation, where the swing velocity is maximum, all the energy – the total energy – is kinetic, with zero potential energy. At intermediate points, there is some mix of potential and kinetic energies. The reed vibration is similar, approximating the vibration of a cantilever. With this “first order” explanation, we now introduce the fact that a relatively small amount of energy is lost from the system, in the form of friction and sound energy, as Wim points out. Thus, motion is maintained by means of the potential energy of the pressurized air in the bellows, or the relatively pressurized air in the atmosphere, when the bellows pressure is less than atmospheric. Wim seeks to explain reed tongue vibration only by reference to the static forces exerted by pressure, but we know from Newton’s Second Law that forces also arise from acceleration (or de-acceleration) of mass. This is the meaning of a dynamic system. As I try to emphasize now and then on this forum, acoustics is a dynamical phenomenon, involving time derivatives, and any complete understanding of its effects must include dynamic (time dependent) effects. Think inertia. Thus, an explanation of a dynamical event that contains only static pressure forces is necessarily incomplete. This incompleteness becomes too much to bear when we arrive at Wim’s explanation of the “4th position,” which I quote below: “But, the pressure P1 build up is less than it was in the 2nd position, and because of this it will allow the reed to continue up to the first position. If the airflow obstruction would have been the same as in the 2nd position, the swing cycle could not be completed. A reed swing cycle is not symmetrical. The amount of obstruction in position 2 is larger than in position 4. Also, the rest position of the reed is not exactly parallel to the frame. The tip is slightly above the frame. This means that the tension energy in the reed helps it move through the blockage.” I think it’s fair to say that this passage needs complete overhaul. Here’s how I would describe the state of the reed in Position 4, as it moves upward: At Position 4, the total net pressure force acting on the reed tongue is (P1 – P2)*A, where A is the reed area, and this is the same net pressure force acting on the reed tongue in Position 2. The difference here is that the tongue is moving upward, and thus, it’s inertia carries it through Position 4, against the net pressure force and against its own spring force, just as a swing is carried from a low position to one higher, against gravity and against a small nudge, say by wind, against its motion. It’s clear that, when one invokes all the dynamical elements, the explanation becomes much simpler and intuitive. The convoluted, and erroneous, explanation given by Wim results primarily from his attempt to make only static pressure forces account for all the tongue motion. There are other, less important, aspects to Wim’s explanation that I disagree with. Under “Bellows pressure,” he states that the pressure applied to the bellows is the force applied by the player, “divided by the size of the bellows: P = F:S” I understand his meaning, but it would be a simple matter to be more precise, with dimensional correctness, by stating that the pressure is approximately the force divided by the end plate area: P = F/A. For a “perfect bellows,” one that is infinitely flexible and frictionless in the direction of motion and infinitely rigid in the direction normal to motion, this equation would be exact. Under the explanation of the 2nd position of the swing cycle, Wim states that, when the tongue arrives at this position, “In doing so, the reed causes the pressure P1 to increase considerably.” In truth, P1 doesn’t increase. As we stated above, this pressure is determined only by the players force on the bellows, and we can assume that it’s constant. I believe this mis-statement arises simply because his explanation does not recognize that it is a pressure difference that forces vibration, and not simply P1. At Position 2, and Position 4, the net pressure force acting on the reed is, to first order, (P1 – P2), which is the maximum pressure difference attainable. At positions other than 2, or 4, the pressure difference acting on the reed tongue is (P1 – Px), where Px is intermediate between P1 and P2, determined by air flow dynamics, and can be approximated to first order by the (quasi-static) Bernoulli Equation. The Bernoulli Equation is very helpful in explaining the swing cycle of the reed tongue. In fact, the Bernoulli Equation, for steady flow, is actually a statement of Conservation of Mechanical Energy, in the same way that the reed tongue vibration, to first order, conserves energy, shifting the mix of potential vs. kinetic energies. When air is in motion, it has kinetic energy, and thus it’s potential energy, measured by pressure, is decreased. That’s Bernoulli, a beautiful understanding of how Nature works. Thus, when the reed tongue is in Position 3, below the slot, air flow above its top surface means that the pressure here is (from Bernoulli) somewhat less than P1, and the lowest it could be (with a maximum velocity) is P2. The important term, the pressure difference across the tongue, is (Px – P2), somewhat less than (P1 – P2). Here, a combination of pressure difference and kinetic energy of motion propels the tongue downward to its minimum position, where it's kinetic energy becomes zero. In section, “Reed shapes and frequencies,” there appears: “Unlike other reed instruments (e.g. clarinet, sax, etc.) the vibration of a concertina and accordion reed itself hardly produces any sound.” I don’t think this is an entirely correct distinction. In all these instruments, the reed initiates a pressure pulse that results in the sound that we hear, and the distinction with the free reed is much more subtle. With a clarinet, for instance, the reed acts as a pressure valve that closes the end of a quarter-wave tube at precisely the right time, causing air molecules to collide against it, in the same way they collide against the free reed tongue, providing a pressure pulse that contributes energy to the resulting standing wave vibration in the tube, and some of this energy escapes the tube in the form of sound. The air column in the clarinet thus provides a storage mechanism whereby traveling wave pressure pulses can attain perhaps higher magnitudes than those attainable by the free reed. (I don't know if this has been proven by the way.) The free reed has no similar mechanism by which to bounce back pressure pulses in order to grow amplitude. But even this isn't the whole story, because of the relative areas involved. The wind instruments have openings to the atmosphere that have more area than the total area of the free reed. (I'm assuming this last statement.) But since the free reed in fact shuts off air flow, causing a collision with air that produces pressure pulses, why would you say that the reed "hardly produces any sound?" This is all the sound the little thing has! And many a fiddle player I know think it's too much sound! Thus, simply speaking, both reeds produce a pressure pulse by colliding with air molecules, causing pressure pulses, which result in sound that we hear. The way I would state the primary difference between the free reed and the reeds of these other (beating) reed instruments is that, in these other reed instruments, a vibrating column (tube) of air – not the natural vibration of the reed - defines the frequencies of the musical tone, whereas in the free reed, the frequencies of the musical tone are defined primarily by the natural vibrational frequency of the vibrating tongue itself. An additional distinction arises from the quantity of “useful mass” set into vibration. A vibrating air column is much more effective than is a vibrating metal tongue at converting its vibrational energy into sound waves that make it to our ears. Hence the difference in volume between a trombone, for instance, and a concertina. In this same section, there also appears: “The length and thickness of the reed determines its frequency. The width of the reed does not play a role in this. In fact, two reeds of the same length, material and thickness, but one of them twice as wide as the other, will swing in the same frequency. The width does however have an effect on its swing cycle, because the larger surface of the reed increases the air flow pressure (P1).” I think the first part of this statement is accurate, although the last sentence is not correct, simply because the net pressure force scales as the tongue area, and the area scales the same as the other parameters (spring force and mass) that determine the vibratory motion. Thus, doubling the width doubles the area, doubles the net pressure force, doubles the mass and thus the inertia force, and doubles the spring restoring force. There are no other parameters, to first order, that determine the motion, and thus, the two tongues vibrate in theoretically identical ways, with the same swing cycle. In summary, I again applaud Wim’s attempt to explain to the layman just how a free reed works, but I think we all need to bear in mind that there are many serious studies going on by devoted physicists on how these devices really work, and our total understanding of their operation is increasing. With this physical, reproducible understanding, we see a beautiful exposition of Nature’s laws, and I hope my comments are taken by all here as only an attempt by me to do what I can to entice a broader curiosity into such of Nature’s phenomenon. Best regards, Tom www.bluesbox.biz
  20. I meant for this comment to be included in the thread on the Elise, but after composing it, I found that that thread got locked. Can someone explain the lock? Hi Wim. This is a verrry interesting comment. I for one would be most interested in seeing a discussion involving such “measurable facts.” But before we need even start such a thread with actual data, let’s see how far we can get in simply defining the following parameters in terms of other, measurable quantities: 1) Air consumption 2) Maximum reed amplitude 3) Air flow economy 4) Reed coasting 5) Harmonics 6) Pitch stability 7) Equilibrium 8) Key pressure (force) 9) Key travel Wim, I’m not sure how far along you are in this issue, but I think some of these quantities are much better defined than others. For instance, (1) can be measured by pressurizing the bellows to a standardized level (say 5” water column), then measuring the air flow required to maintain constant bellows pressure while a key to a specific reed is totally depressed. Thus, for each key, a particular “Air Consumption” value would be specified. (2) Maximum Reed Amplitude could be defined by placing a test reed on a cavity made with standardized geometry, then delivering air to the cavity by a standardized air delivery system, with a corresponding measurement of the vibration amplitude of the very tip of the reed, which can be done by eye using a simple machinist’s scale, or even by a more sophisticated, yet still simple, scale. (3) Air Flow Economy. Wim, here, I’m not sure how you would define this quantity. I see competing definitions, but I’d think that the best definitions would involve audio output. However, sound measurements introduce a tremendous complexity, thus, a simpler and more practical definition might include, in place of a sound measurement, a measurement of pressure drop across the reed. But we already have such a parameter in (1). Can you elaborate further? (4) Reed Coasting. I’m not sure what you mean here, but I think this parameter might consider the transient vibration of the reed tongue that persists and finally dies out after the delta P across the reed is removed. How do you quantify this parameter? What value do you see in it? Can this parameter be changed without changing other, perhaps more important, reed parameters? (5) Harmonics. Measurement and evaluation of harmonics can possibly lead to great confusion, though there might be something useful here. If so, then perhaps the criteria by which a definition is made must ultimately rely on subjective reactions. For me, I might for my own purposes look at amplitude ratios between different overtones, with respect to the fundamental, because I myself am averse to higher harmonics, and I see possibly an advantage to have the lowest overtones dominate. Can you reveal to us your own criteria here? (6) Pitch Stability. Although I’m not sure, you may mean that pitch stability is the ability to maintain a constant pitch of musical tone as the delta P across the reed is increased. I’m sure we’re all aware that the free reed tends to flatten in pitch above a certain maximum pressure drop. In this case, a useful definition of Pitch Stability might be the ratio of pitches, or the percent drop in pitch when two standardized pressure drops are imposed – one at typical playing pressure, and the other at the largest expected to be encountered during actual performance. (7) Equilibrium. I don’t understand what you mean here. Please explain. (8) Key Pressure (force). I think this parameter has already been used now and then in the literature and on this forum, and I’d define it as simply the total force it takes to depress a key the maximum amount. (9) Key Travel. Again, this parameter is relatively simple and is already in use. Wim, do you mean to say that you have these nine parameters in numerical form as a way to quantify the performance of all of the instrument models you sell? Do you include them with purchase of the instrument? If so, I’m impressed. I think it would be a significant addition to the trade if such parameters – and perhaps others - could be adequately and rigorously defined, as a way to compare instruments – not only those between different makers, but also those by the same maker. Can you please explain what "ampliphonicly" means? Best regards, Tom www.bluesbox.biz
  21. Pat Missin is a notable authority and a very accomplished musician when it comes to harmonicas. He maintains an exhaustive informational web site on harmonicas and other free reed instruments: http://www.patmissin.com. I invited Pat to make relevant comments in this thread, and he came back with the following response. Some of the ideas he expresses have already been mentioned, and I've explained my own views, some of which don't completely accept the normal bending explanation that Pat gives. There's also a relatively new development for free reed instruments, and Pat points this out at the end, linking us to a very interesting sound file he himself recorded. I do believe this latest development can have a significant effect on the future development of concertinas as an expressive musical instrument:
  22. Hi Ransom, Thanks for going through the trouble to make the video. I’m always amazed by the power of the web. Let’s all hope we can keep net neutrality. No, no, no, it's easy to reproduce your results. Let me explain. The fact that the reed chokes when you try to draw bend while covering the slot proves to me that you have very good acoustic coupling between the reed and your vocal cavity. The coupling in this case is much stronger than when the slot is not covered. Thus, in order to produce the bend with the covered slot, you cannot use the same vocal tract geometry that you use with the uncovered case. I suggest you try practicing the covered bend, but with only a slight modification of your vocal cavity. It’s easy to choke a reed when you have good acoustic coupling. I can do the same thing as you, with little effort. This effect is also easily shown when you try to play accordion reed blocks as you would play harmonicas. The reed leathers present likewise allow strong coupling, and you cannot be very aggressive with your throat gymnastics. In a thread on this forum a couple weeks ago, there was a discussion on why drilling a hole somewhere in the reed cavity would prevent some very high concertina reeds from choking. All these phenomena are similar: when the air coupling between a reed and an associated geometry is strong enough, and when the resonant frequency of the air geometry is close enough to that of the reed, the reed will choke. So in a sense, the fact that you can now choke the reed with your vocal tract proves how immensely improved acoustic coupling to your vocal tract becomes. You just have to be a little less aggressive with your oral talents. The fact that the uncovered bend is easier for you only suggests to me that this is the situation you are most used to. Bear in mind that both Ardie and I find it a trivial task to bend on a draw with covered blow slots. The fact that you can’t do it doesn’t prove we cannot. I suggest only that you need a little more practice. This is not surprising to those who are aware of the intricacies in playing a musical instrument. The fact that the blow reed vibrates in the uncovered case may lend support to the Johnston crowd on their claim that a blow reed of lower pitch is required for the normal bend. But at the same time, it doesn’t prove their claim, simply because we don’t really know where the sound is coming from. It would be interesting if, during this bend, you were able to cover the blow slot, without the slightest change in any other parameter of the bend (vocal tract shape and airflow intensity) I’ve tried this many times, and it isn’t easy to do the experiment controlled, when I use a spare finger to cover the slot. My conclusion is, again, the blow reed isn’t really participating in the bend. It’s not surprising to me that it will vibrate during the bend, but only in the manner of a passive sympathetic action. Remember now, the vocal tract in this case may have a resonance frequency closer to the BLOW reed, in which case the air vibration is what’s causing the blow reed to sympathetically vibrate, not the other way around. One last point: it seems to me that normal draw bends are relatively easy on the lower half of the unvalved harp perhaps because the resonant frequency of the modified vocal tract becomes close to that of the blow reed during the bend. This coincidence of frequency causes the blow reed to sympathetically vibrate, which, in effect, partially seals the blow slot, increasing acoustic coupling between the slot and the air column. On the other hand, with the upper half of the instrument (where the secondary reed has pitch higher than the primary reed) the resonant frequencies of the vocal tract and the blow reed are now too far apart to induce sympathetic vibration in the blow reed. Thus, sufficient acoustic coupling with the air column is not achieved, and bends are much more difficult because of air leakage through the blow slot. The same comments apply of course to blow bends. These statements are only guesses and would require verification by experiment, and possible theoretical study. I really wish someone more knowledgeable than me on harmonica playing would chime in here. I’m just winging it here. Best regards, Tom
  23. Thanks for the document, Chris. It seems that there are two major types of action: the "rivoted" and the "pivoted." I realize there are some complications in the constructions, but is there any consensus on which of these two types of actions are basically more durable, faster, smoother, etc.?" Regards, Tom
  24. Hi Ardie, Let me also summarize what I see as the difference between our views on the issue. We both agree that, with “windsavers” - valves placed on the back side of the slot of each reed -, single-reed bends are greatly facilitated, for all of the ten holes in a standard “blues harp” instrument. For me, this fact may, but not necessarily, indicate that single-reed bends are possible in the un-valved instrument, and I’m surprised that others – call them “the Johnston crowd” - claim that the only “normal” bends made with the unvalved instrument are “double-reed bends” – bends that require the presence of two reeds in the same slot, accompanied by the influence of an air resonator (oral/vocal tract). I myself do not claim that these people are wrong, and I’m willing to accept the possibility that they are right. (Johnston’s paper gives strong experimental and theoretical evidence that they are right.) If I understand your position, you seem to differ from me only that you say that these people are indeed wrong. You simple go further than I do, on this issue. I must thank you for your document, which is valuable here, and it helps make certain things clear to me. For one, it lays out before us all what the Johnston crowd claim; i.e. that the only “normal” bends you can do on an unvalved blues harp are bends on reeds that have, as accompanying reed, one with lower pitch. Look at your evidence on this point. The only exceptions you show are with holes 5 and 6 on the blow, where the accompanying reed is of higher pitch. You indicate that the bent sound is difficult to hold, because of the parentheses. Thus, would you not agree that your chart gives considerable evidence for their claim? Okay, I say we are both skeptical, but maybe we just haven’t yet heard enough of the evidence that’s already out there. I read Johnston’s paper many years ago, and I honestly cannot remember how convincing it is. I need to read it again before making any more statement on it. Concerning the evidence you seek, I’ll mention again that the Asian free reed is indeed a reed that necessarily operates as an “opening” reed. If you don’t understand what this term means, I suggest you read Cottingham’s paper, referenced above. As the Johnston crowd explains, the additional reed in the harmonica operates as an opening reed during the bend, in the same way as the Asian reed, and both require coupling to an air resonator. But perhaps the best evidence I can point to at the moment is the Johnston paper. If you (or anyone else) would like me to send you a copy, email me with your address. In the Johnston paper, both experimental and theoretical evidence is presented. With the experiments, they made use of an actual unvalved instrument, powering it through a resonator of variable geometry. I should read the paper again. Being only an amateur, I’m not as familiar with the literature as I could/should be. Here, I think you go too far, and I think there are physical errors in your understanding. I believe you are in error when you say, “bending primarily involves a changed influence from the airstream and pressure on the singular reed,” if, by “bending” you mean the normal bending – not overblow. With overblow, I agree, a non-uniform air flow (i.e. jets) may be involved. But not so with the normal bend, on the draw. It’s not impossible to form a non-uniform airflow through the reed when you draw. The flow through the reed is then upstream of your mouth, where the vacuum is, causing an air flow approach to the reed is that must be uniform. I’m not sure what happens when you do a normal bend on an unvalved harp with a blow – one reason being because I never learned how to do it. But with a valved harp, the blow bend is produced also by a uniform flow, without the “whistling” you explain for overblows. I strongly disagree. As I noted above, the patterns I see between the primary and secondary reeds give strong evidence for the Johston crowd. One last point I can make is by asking, since you are aware of overblowing (whistling) techniques, isn’t it true that, when you overblow, you also force the reed to speak with an airflow that is in opposite direction to the ordinary? I’m not 100% sure, but I’m pretty sure that, with overblow, the main speaking reed is again operating as an opening reed. I didn’t know that such large bend excursions were possible with the unvalved harp. If it’s true, then I don’t know the answer to your question. I think at this point, we really need someone with more knowledge to chime in. Best regards, Tom
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