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Thoughts On A Combined Reed/action Plate Design


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

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I did not say that the reed is propelled by a sound wave! This whole discussion was generated by someone's implication that if pressure changed at one end of a tube, air had to flow through the tube before it affected whatever is at the other end of the tube.

Could this be the quote which you're referring to?

 

the amount of distance that the air has to travel inside a tube will decrease the loudness significantly,

I think that Łukasz should have said -- and probably meant to say -- was "sound", rather than "air". And I think there followed various misunderstandings because we didn't realize we were actually talking about different things.

 

I suspect and hope that with Łukasz' latest post we're now all back on the same track.

 

Edited to correct small typo.

Edited by JimLucas
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This whole discussion was generated by someone's implication that if pressure changed at one end of a tube, air had to flow through the tube before it affected whatever is at the other end of the tube.

 

I saw a different implication, namely that, before the pressure at the reed end of a significantly long air channel reaches bellows pressure, the air in the channel (which will initially be at atmospheric pressure) must first be compressed. And this process does require the flow of air between the bellows and the channel (like between bicycle pump and bicycle tyre), and thus takes some time.

 

The longer the air channel is (assuming a constant cross-section), the greater the volume of air it will contain, so the longer it will take to get it up to bellows pressure and start the reed. Thus, an arrangement with air channels of different lengths would make for uneven response times among the buttons (unless some form of compensation is included). With the conventional mechanical linkage, on the other hand, distance from button to reed chamber is no object.

 

Cheers,

John

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Lukasz has what seems to me the most important point, which is that you get very substantial sound loss the more distance the sound has to travel through the concertina's guts. We are not talking super conductors of either electrons or sound waves. Concertinas are rife with things that absorb sound. Many of these are frequency dependent. Those of us who have tried out various "bold" schemes to improve the concertina be it double acting reeds, bridge rectified air flow, vertically mounted reeds in tubes like a pitch pipe just to name a few of my sure fire ideas that worked if you count being able to hear the notes at all, as working. None came within a mile of what is needed for a practical instrument, and were a joke compared to the much simpler standard design. There is way too much discussion and theorizing here and too little experimentation. The concertina as we know it today was designed by some pretty smart folks. They had dustbins full of ideas. Most of the development since then has been towards making progressively crappier instruments, ending with the truly terrible Stagis which are even worse than the Bastaris they started out as. There have been small but useful changes to the design by different modern makers. Mine have been geared toward reducing the effects of changing seasons on the instrument. Others have applied accurate and sophisticated manufacturing technology. Nobody has deviated from the basics of reed, chamber, and pad design because so far nothing else has been close to as good. If you are able to make an instrument using ideas like the one at the beginning of the thread, you can make a pretty decent concertina your first time around that you can play good music on by sticking to the highly developed form the best were made with. Airing your ideas here is a good thing if you want to see if you are reinventing the wheel or have something worth pursuing. Nothing says you won't, but the best advice generally comes from people with experience, which is what makes people like Geoff Crabb such a treasure. My own advice is to make simple prototypes before investing much time and effort.

Dana

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