Melodeon.net Forums
Discussions => Other Free Reed Instruments => Topic started by: Mark Leue on April 22, 2019, 12:55:44 AM
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My artist/craftsman brother is moving his studio a couple of thousand miles away to a warmer climate and giving away a bunch of stuff, and I saw a couple hundred brass organ reeds in a pile to be sold for scrap metal and couldn't resist.
They are interesting from a physics and design point of view. I hadn't known until today that the bellows on a foot pumped reed organ work on suction only, and the reeds are designed only to work on "the pull". I have very low to very high notes here and all but the highest reeds have a strange little "s" curve on the ends of the reed tounges. They seem fundamentally different than accordion reeds. You definitely cannot get them to sound by blowing from the back side.
Of course I have no practical use in mind for therm, I just thought they seemed worth saving. I am fascinated however by the science behind how they work. Tried to take a couple of quick pictures of some.
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Look at the tiny high pitched reeds, some with less than 1/16" wide reed tongues! Those ones sound very nice when you give them a suck.
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I hadn't known until today that the bellows on a foot pumped reed organ work on suction only, and the reeds are designed only to work on "the pull".
Pump organs like these are generally known as 'American organs' or sometimes (confusingly) 'melodeons'. Working the foot pedals creates a negative pressure in a wind chest in the instrument, which then draws air through the reeds.
The European version is the 'harmonium' which blows air through the reeds. The harmonium is thought to be more prone to pitch changes with varying foot bellows pressure, but at the same time is said to be capable of more dynamic range and expressive playing.
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"reeds have a strange little "s" curve on the ends of the reed tounges."
They look rather elegant in my opinion, redolent of the cross section of an aeroplane wing? Which makes me think that the shape must increase the airflow over the reed, and hence the efficiency of the bellows and the possible opportunity of increasing the volume of the reed sounding?
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Some of these reeds could be used to build a wonderful single action bass concertina. :D
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or maybe a bass harmonica...
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Unfortunately not really Pete. I worked in a bass concertina that had some reeds replaced with harmonium reeds, and they were not right for that application. Harmonium bellows have a much larger volume and can sustain higher airflow and possibly at at a lower pressure than in a concertina. Harmonium reeds are optimised for these different conditions. I suspect that the elegant curve near the bellows tip is designed to allow the reed to speak at lower pressure.
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The highest reeds seem to start with very low pressure, probably because their narrow width means they have very low mass, Interestingly they appear to have no reed gap. Maybe its not strictly necessary for a pull reed?
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Hi Mark,
If you are ever interested in moving them along, I work on reed organs and could certainly find some use for these down the road. I am in the USA though, so shipping might be prohibitive if you are overseas.
Thanks very much,
Baron
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Unfortunately not really Pete. I worked in a bass concertina that had some reeds replaced with harmonium reeds, and they were not right for that application. Harmonium bellows have a much larger volume and can sustain higher airflow and possibly at at a lower pressure than in a concertina. Harmonium reeds are optimised for these different conditions. I suspect that the elegant curve near the bellows tip is designed to allow the reed to speak at lower pressure.
Oh that's a shame, I just found a reed organ (I call it this as it was built in Chicago so probably not a harmonium as such) for sale 25 miles away from me for £50, I almost bought it!