Jump to content


  • Posts

  • Joined

  • Last visited

1 Follower

Contact Methods

  • Website URL
  • ICQ

Profile Information

  • Gender
  • Interests
  • Location
    Princeton Junction, New Jersey, USA

Recent Profile Visitors

1,620 profile views

ttonon's Achievements

Chatty concertinist

Chatty concertinist (4/6)

  1. If you're interested in a theoretical explanation of this, I believe it's because at those high frequencies, resonances of the chamber interfere with the self excitation mechanism that makes vibration of the reed tongue possible. The resonance can result from the cavity acting like a Helmholtz resonator or a quarter wave tube. You can read more detail at https://concertina.org/pica-volume-2-2005/reed-cavity-design-and-resonance/ Best regards, Tom www.bluesbox.biz
  2. This is not correct. The tone of a free reed contains exact harmonics (exact multiples of two), like that from any other instrument that plays sustained tones, such as the violin, woodwinds, and brasses. Different are the instruments that play tones generated by transients, such as the piano, guitar, xylophone, bells, etc., and their tones contain overtones that are not harmonics. That's what makes the musical tones of these latter instruments interesting, particularly when multiple tones speak. The fact that the tone is sustained over multiple cycles of vibration requires that the harmonic series occurs, otherwise periodicity would not exist. You cannot have a sustained tone without exact periodicity of all its components. That would be a contradiction. Woodwinds and brasses interestingly differ from the free reed in that their vibrating air columns have the ability to generate overtones that are not pure harmonics, but the frequencies at which those overtones (their peaks) occur in the sustained musical tone, which involves other overtones, differ from the frequencies at which the peaks occur. You can generate a tone by exciting only one of these overtones by some artificial means (not by a player's mouth), in which case, the peak of the overtone frequency will appear. But when that overtone is in concert with others in a regime of oscillation (single tone) from the instrument, those overtones often vibrate away from their peaks, at the frequency that corresponds to the harmonic series. In fact, with some instruments such as the trumpet, some overtones contribute only a fraction of their peak amplitude to the musical tone, depending on the note being played. With minor exception, only the fundamental transverse vibrational mode of the free reed tongue generates the musical tone. The overtones of the tongue vibration can be sometimes measured by sensitive instruments. It's not clear however how much they can be heard. Even the first torsional mode of tongue vibration can sometimes be measured in the musical tone during the start transient. But it quickly disappears during the steady state (periodic) tone. The overwhelming steady state tone from a free reed is the result of the ear/brain system's ability to break a periodic sound into its Fourier components. Or at least, that's how we understand it. This ability is remarkable and mysterious, and it's connected to the magical way mathematics can provide an accurate description of physical phenomenon. Even if such inharmonicity would occur in a concertina, it would be neigh impossible to filter it out by means of passive filters. Best regards, Tom
  3. Cornishman, you seem to have great powers of imagination. Have you done any calculations on the required length for such a passage? My guess is that it would be far longer than your outstretched arms. Can you imagine that? And that would do nothing for the sound that escapes through the walls of the bellows. It would be far easier to put yourself in a closet and close the door. Preferably a closet that's stuffed with clothing on hangers. But of course, in this heat wave, you'd better bring in an air conditioner that exhaust hot air to the larger room. And then the sound of the running air conditioner would cause you to hear the concertina less. Oh I see, you want others not to hear the concertina. O well, just one more brilliant idea shot down. 😄 Best regards, Tom www.bluesbox.biz
  4. Yes, wetness helps also when you use your face, or other sensitive body parts. The increased evaporation enhances the cool feeling.
  5. If I understand correctly, this instrument differs from the conventional bandoneon only in the keyboard arrangement of how/where the notes appear and that the sound sources are conventional free reeds (it's not an electronic instrument). My guess is that there thus should not be much difference in the sounds between the two instruments, unless the positional arrangements of the reeds have some subtle affect on sound. I agree with many here that it sounds mellow, and that also means that I don't hear the more shrill higher frequencies that I hear with the conventional instrument in the upper half of the tonal range. It's a bit puzzling why those overtones are not there, if the traditional 2-notes per key (an octave apart) is maintained with the new instrument. For me, those shrill tones, and I believe for many others, adds to the startling effect traditional bandoneon music offers. But maybe I'm just not hearing what's really there. In that regard, how is this recording made? How many mics were used and where were they? I'd say this sound file is only an introduction to the enormous range of effects this particular bandoneon should offer, and it would take a skilled musician playing with full dynamic excitement to make a full evaluation. I do see the potential that a simplified/uniformized keyboard has for beginners, and this may be the greatest advantage of the new instrument. Best regards, Tom www.bluesbox.biz
  6. Well, how big is a pore? If around 0.1 mm, that would give a frequency of the order of a couple million Hertz! I don't think even dogs can hear those. Tom
  7. Hi Devil, if that's the case, maybe a fibrous plastic that doesn't shed would be useful, such as the one side of Velcro strips, which seems like a dense cluster of fibers that offer much surface area on which viscous forces can act, as with felt. Best regards, Tom
  8. Hi David, the effect I believe would be too subtle to notice. For sound attenuation within pores or cavities, the sound must cause air vibrations so that frictional (viscous) work is done in the boundary layers, and for that to happen, the dimensions of the cavity must be not too far different from the wavelength of the sound. So with wood, the depth of the pores is so small only extremely high frequencies would be affected. The table below shows that wood offers very little attenuation at the higher frequencies. I also have doubts that the effect of wood density would have much effect on impinging sound waves. It could have an effect on the vibration of the tongue, but not much effect on impinging sound waves for the reasons I explain above. If the wood structure vibrates from the pressure oscillations in the sound, that could cause some attenuation, because that vibration will cause viscous dissipation (friction) that absorbs the sound energy, though this is likely to occur only for the lowest frequencies that couple with a resonant frequency of the wood structure as a whole. And there, wood density could have an effect, but only to help determine the particular low frequencies the structure vibrates at. The table below shows this effect, wherein the absorption coefficient for wood is much higher at the lowest frequencies, presumably because a region of the wood is set to vibrate.
  9. March, I agree with what you say. My own response didn't consider the frequency response of absorption, and you got it better. In fact, I attach a figure showing how the sound absorption of felt increases with increasing frequency. The three curves shown are for different thicknesses (4, 8, 10 mm) and densities (76, 116, 148 kg/m^3). Here's the source: https://www.researchgate.net/publication/321858922_Improvement_of_the_sound_absorption_performance_of_jute_felt-based_sound_absorbers_using_micro-perforated_panels/figures?lo=1 Best regards, Tom
  10. Hi Jason, What do you mean by "mellow" the sound? My guess is that you mean less harsh, which often translates to a reduction in higher overtones. If that's the case, I don't think it would do that because felt would likely attenuate most all the overtones, resulting in only a reduction in volume. In some full size accordions, makers invented what they call a "cassotto," which is a 5-sided box, or slot, or chamber, in which the pallets are mounted. This acoustic feature is fairly effective at mellowing the tone for much of the pitch range of the instrument. It's most effective on the lower notes, because of their frequency relation to the dimensions of the chamber, and I don't think such a device can be effective the entire pitch range. It's used by most jazz players in the States, who describe the sound as "ballsy." I suppose it's possible to build such a thing for a concertina. Good luck! Regards, Tom www.bluesbox.biz
  11. So was I, keep us informed. Tom www.bluesbox.biz
  12. Hi Sven, Most the PA reeds I've seen have the heel of the tongue, which is spring steel, extend past the midpoint of the plate. One tongue on each side of the plate. In order to split the reed, it would be simplest to cut the whole thing lengthwise with a carbide tool. But the cut must be pretty thin (it's kerf), and I'm not aware of carbide cutting wheels that thin. Alternatively, you'd have to take out the tongues, cut the aluminum plate, grind down one side of the tongue heel, then re-assemble. A lot of work. I think your second option is much easier. There could be a question of how much the tone is affected by moving the pitch so much. My guess is that this issue is much less with raising the pitch than with lowering it. Raising the pitch requires removing mass near the tongue tip, and lowering it requires removing mass from the heel end, which I believe affects dynamics much more. I'm sure others here have more experience with that. I haven't checked, but there might be clever ways to choose what PA reed to use for a particular cavity. For instance, there may be PA pitches that would allow tuning both tongues, which would require less of a pitch change for the tongue whose pitch must be lowered. Best regards, Tom www.bluesbox.biz
  13. While on this topic, is there a consensus among makers which action is superior, if any, the hook or riveted? Thanks. Tom
  14. Paul, thanks for your helpful measurements. Alex, thanks for your detailed explanation. I calculate that the average spread in all of Paul's measurement to be 0.0059 inch, or +/- 0.003 inch. Can you estimate the average gap between tongue and slot that you get with your finished product? If I recall correctly, Dana once commented that his gaps are maximum about a half thousandths of an inch. Paul's measurements indicate that the slot inaccuracies don't follow the same trends among the different results, and that would perhaps make filing the tongue more tedious. I'm curious how you visualize the gap in order to see how your filing is going. I once used an optical comparator, which, on an overhead screen, displayed a very magnified version (10x) of whatever you placed on the table, which had a glass surface that was backlit. I'd think that such an apparatus could be very helpful for this kind of work. Regards, Tom
  15. As you know, you can verify an acceptable fit with your eyes, by looking at the gap between the tongue and slot through a bright light. But it's another issue to measure and provide quantitative data that others can evaluate. So, too bad you don't have a way to do that.
  • Create New...