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ttonon

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About ttonon

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    Chatty concertinist

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    http://www.bluesbox.biz
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    Princeton Junction, New Jersey, USA

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  1. HI Little John, you raise an interesting question that I hadn't considered, and my first response will be to rely on the differences in the mechanisms by which the two musical tones are produced. Let's first look at both cases starting with the time the tongue starts to hit the plane defined by the top surface of the underlying plate. The beating reed hits the plate, and the free reed enters the slot. When the beating reed shuts off airflow, a rarefaction (reduced pressure) wave passes down the pipe, the resonator, at the speed of sound, hits the open end and is re
  2. I may as well have fun with this, but first, I'm assuming that by "rounded edge" you mean that the very thin side of the tongue is not a flat plane at right angles to the upper and lower surfaces, but rather it has a curved, convex shape . I base my comment on that picture. I tend to agree with Chris that such a feature should not affect the sound too much. But as usual, we can devise other possibilities in special instances. Such as the start transient and the amount of pressure needed to start vibration. Since the quiescent tongue offset is sometimes comparable to the tongue thickn
  3. John, again I'm not making myself clear. So I'll try again. When I say harmonic I mean harmonic, which is a mathematical term indicating whole number ratios. When I say harmonics, I'm not referring to the bending modes of the cantilever, which are not harmonic. As you probably know, the second bending mode has a frequency roughly 6.2 that of the first bending mode. The statement, "I take the clang tone to be the first bending harmonic" is erroneous. The clang tone is the second mode vibration, with it's fundamental roughly 6.2 times the frequency of the first mo
  4. Hi Dana, I had a hunch that I wasn't getting my point across. I'll try again. We agree that the cantilever vibrates in different bending modes, and that its first (transverse, or bending) mode is the one that dominates in the free reed. Now, with that mode, there are also harmonic frequencies in time. The fundamental of those harmonics is the chief vibration we observe; i.e., that's the sinusoidal motion (in time) that causes the chopping of the air stream. However, there are also higher harmonics in that time vibration. As I said, it's best to describe this as a kind of jerkiness in the
  5. Hi Dana, I know we discussed this before, but now I'm confused. "Air driven reeds produce a completely different set of actual harmonics in the 1,2,3,4 etc.X the fundamental." Are you talking about harmonics in the acoustic pressure wave form that we hear, or harmonics in the time dependency of the mechanical tongue vibration as a bar, within it's first transverse mode of cantilever vibration? "In my experience, air driven reed waveforms are only slightly sawtooth..." Again, are you talking about the acoustic pressure waveform that we hear, or the mechanical vibration of
  6. Hi Alex, if that confuses you, let me confuse you further by a similar plot made by a different investigator, James Cottingham, one of the pioneers in experimental investigation of free reed physics. The figure caption explains the set up and notice the similarity between Ricot's measurement for pressure above the reed and this one: two humps roughly in the same place, with one hump significantly larger than the other. Notice also the complex pressure waveform in the cavity below the reed. That's all I want to point out here. In my view, the Western free reed can rank as the most diff
  7. A picture is worth much speculation and many posts. The attached plot shows the pressure upstream of a vibrating free reed, with time on the Abscissa. The reference is: "Aerodynamic excitation and sound production of blown-closed free reeds without acoustic coupling: The example of the accordion reed" Denis Ricot, Laboratoire de Me´canique des Fluides et d’Acoustique, UMR CNRS 5509, Ecole Centrale de Lyon, France; Rene´ Causse´ and Nicolas Misdariis Institut de Recherche et Coordination Acoustique/Musique, UMR CNRS 9912, 1 place Igor Stravinsky 75004 Paris, France
  8. Hi Wunks. I don't know the manufacturing process for these tines, but I'm pretty sure they are hardened steel. It's curious why they provide such excellent material for musical triangles. I have one, made by Larry Miller, a Cajun accordion maker in LA, and it's a perfect musical triangle because it does NOT have a dominating pitch, at least for playing Cajun music. Thus, it can provide a wonderful percussive effect, regardless of the key of the song being played. In contrast, many other musical triangles that are used in orchestras produce a boring "sinusoidal" acoustic sound, which l
  9. Steve, maybe you want to explain a little more because the maker's website seems to be offering a brand new machine for less than you're asking. Please explain why you're selling it and how the model you're selling differs from the models that are being offered for less money. Thanks. Regards, Tom www.bluesbox.biz
  10. Hi Steven, thanks for pointing out the difference in terminology, which I wasn't aware of. I found a video comparing the sound of a harmonium to that of an American reed organ, for those interested: In addition, Wikipedia gives the following distinctions: > Reed organs are operated either with pressure or with suction bellows. Pressure bellows permit a wider range to modify the volume, depending on whether the pedaling of the bellows is faster or slower. In North America and the United Kingdom, a reed organ with pressure bellows is referred to as a harmonium, wherea
  11. This seems even more interesting to me, and I never heard of or considered such a twist. You see, I think the sound of the free reed is boring, because of its perfect partials. By "perfect partials," I mean that all overtones are harmonics. "Harmonics" is a mathematical term that means multiples of two. Thus, any overtone of the free reed are perfect multiples (or divisor) of two with any other. The only "fly in the ointment" here are so-called transients and some cases of very loud playing situations that excite either torsional or higher vibration modes, which in general are not multipl
  12. For those interested, I'm not sure how many of you are aware that harmonium manufacturers have their own standards about "best practice." Here's a drawing of one of their free reeds. I'm under the impression that the curious bend is rather typical. Can anyone here venture as to its advantages?
  13. Hi Don, pump performances are given by their "pump characteristic curve," which all have a characteristic shape shown in the attached figure. You see that at zero flow (cut off), they produce maximum pressure. That's because the power output is almost constant, equal to the product of pressure difference times flow rate. As one increases, the other decreases. That's a rough guide. Even at zero flow, the pump is still putting out power, only it's all going into dissipation and heating the fluid. For a single reed, the air flow rate is extremely small, down around 10E-5 cfm.
  14. Hi Don, the key specification is exit pressure, not volume flow (cfm). None of the axial fans you link to can push air with enough force in order to develop the pressure you need. For tuning, you'd like at least a couple inches of water pressure, and those axial fans can deliver only tenths of that. You need a centrifugal blower, or a regenerative blower for tuning. If you want to power the reed with a full range of possible bellows pressure, get one that has a spec for maximum exit pressure (at zero flow) of at least, say 6 inches W.C.. The axial fans you link to do not even have a spec
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