Geoff Wooff Posted May 10, 2020 Share Posted May 10, 2020 (edited) Following Stephen Chambers' comment regarding concertina reeds having tapered tongues, on the recent Lachenal reed shoe thread, which made me think ' do all concertina reeds have tapered tongues /slots ? My memory is that this is not always the case. At the moment I have only two concertinas, but a tin of old/ spare reeds by various makers proved all to have tapered tongues, however , of my two instruments one has parallel tongued reeds. Both are Wheatstones , the parallel reed model, a raised metal ended treble English, dates from about 1898, it has a lovely full tone , of bell like quality. The other is a 1927 Aeola with tapered reeds , very well balanced throughout its 4 octave range and a good strong tone with wooden ends. To my ear the tone of these two concertinas differ considerably, although they are not at all the same model but, I have encountered several very similar to the 1898, but dating from 20+ years later, that do not have that same tone quality. Condition is a big factor but just how much difference could be attributable to this one detail ? Measuring the tapered reeds: the smaller ones appear to be .005" (.127mm) narrower at the tips, the mid sizes perhaps .008"(.2mm) and the biggest taper by as much as .011"(.28mm). Not a great amount of taper but fairly constant throughout the range. An old accordion reed bank I inspected this morning shows parallel tongued reeds on the lower notes and tapered tongues for the higher notes, so I see the possiblility of using width to help achieve pitch . Any thoughts ? Do modern makers use tapered or straight reeds ? Edited May 10, 2020 by Geoff Wooff Link to comment Share on other sites More sharing options...
alex_holden Posted May 10, 2020 Share Posted May 10, 2020 On my current instruments I progressively vary them from parallel on the lowest notes to about 0.8 degrees on the highest. A taper makes it easier to get a good fit, but I feel that if you taper the low reeds you have to use a less optimal profile (thicker at the tip). I don't have a clear idea what effect it has on the tone but I know it is only one of many variables. Link to comment Share on other sites More sharing options...
Chris Ghent Posted May 10, 2020 Share Posted May 10, 2020 Some (excellent) modern makers use parallel reeds but this may be related to methods of construction rather than tone or response. Some time ago I measured the difference in surface area of a parallel reed compared with a typical tapered reed, can’t remember the pitch, and the parallel was 3% larger. Not enough to make a signal difference, I thought. It does mean a low reed can be a little less thick at the tip but so what? Of course, it will need to also be thinner in the belly. A high reed will need to be thinner at the tip, mmm, could be meaningful. For the same degree of taper in the reed window relief the tapered reed will lose pressure earlier. Also could be meaningful? Link to comment Share on other sites More sharing options...
Dana Johnson Posted May 10, 2020 Share Posted May 10, 2020 1 hour ago, Geoff Wooff said: An old accordion reed bank I inspected this morning shows parallel tongued reeds on the lower notes and tapered tongues for the higher notes, so I see the possiblility of using width to help achieve pitch . My two Jeffries (nw sold) both had tapered reeds with .010 difference in width from base to tip regardless of length, which gives a nice scale for percentage of taper relative to length / pitch. My Wheatstone duet and some other Wheatstones I have checked had parallel reeds, but they made so many kinds of reeds, I am not surprised by your tapered Aeola reeds. One thing that needs to be taken into account, is that tapering a reed is a close equivalent to a reed profile that is thicker toward the root. If you simply increase the width of a parallel reed, you just make it a stronger spring, but don’t change its pitch. If you only increase the width towards the root, you add greater stiffness overall, but without the compensating mass at the tip, so all else being equal, the pitch will be higher. Because Increasing thickness increases stiffness faster than increasing width does since more material is farther from the center of bending, it isn’t strictly identical to changing the reed profile. What I think is important, is that tapering a reed allows you to have higher reeds being longer than they would be if they had been parallel at the same pitch and overall stiffness. Since large lower reeds are generally louder than small reeds, having longer and hence larger high reeds could help with balance. This isn’t too much of an issue for instruments with the range of a c/g Anglo or a 48 button treble, but on a duet or even something like a 56 button tenor treble, the difference in size between low and high is more extreme and you start to see efforts to decrease the output of the lower reeds. I have been fitting reeds for a long time, and find no need to adjust the fit with anything but a rather large file. It is pretty easy to hold a large file straight and I found it took very little time to get a feel for how much bite the file is taking. Adjustments of .0001 inch are normal. Using the taper to fit the reed does work well, but I don’t think that was the reason it entered reed design. Tone of different reeds in different concertinas is a tough nut to crack. Different models can have construction details and materials differences that can dominate the sound, so it may be hard to pin the tone on the reeds alone. But, in reed organ literature, longer narrow reeds are said to be less bright than wider reeds. Wheatstone made a type of reed where the side edges were rounded, and were advertised as a better class of reeds. Those kinds of changes can be tied to the reeds more easily. Same for short scale vs long scale reeds. Just because tapered reeds are a combination of narrow and wide, I wouldn’t be surprised if they tended toward brightness. From looking at reed waveforms, I’ve seen the higher pitches having more Sinusoidal wave forms, and perhaps they benefit from the extra brightness. Since this is so prevalent in the accordion industry, it would be interesting yo hear their take on it. Dana Link to comment Share on other sites More sharing options...
Dana Johnson Posted May 10, 2020 Share Posted May 10, 2020 34 minutes ago, Chris Ghent said: For the same degree of taper in the reed window relief the tapered reed will lose pressure earlier. Also could be meaningful? This is an interesting effect of tapered windows, and perhaps might be assisting in response? Link to comment Share on other sites More sharing options...
alex_holden Posted May 10, 2020 Share Posted May 10, 2020 1 hour ago, Chris Ghent said: Some (excellent) modern makers use parallel reeds but this may be related to methods of construction rather than tone or response. Some time ago I measured the difference in surface area of a parallel reed compared with a typical tapered reed, can’t remember the pitch, and the parallel was 3% larger. Not enough to make a signal difference, I thought. It does mean a low reed can be a little less thick at the tip but so what? Of course, it will need to also be thinner in the belly. A high reed will need to be thinner at the tip, mmm, could be meaningful. For the same degree of taper in the reed window relief the tapered reed will lose pressure earlier. Also could be meaningful? Hi Chris. My hypothesis (which could certainly be wrong) is that if you make the tip of a bass reed thicker, it will need to travel further on the downward half of the cycle before it dumps enough of the air pulse for it to start back up again. That might mean it takes slightly longer to reach full amplitude, and could contribute to increased pitch bending. At the high end, tapering them means the tip doesn't need to be quite as ridiculously thin as it would if it were parallel. Link to comment Share on other sites More sharing options...
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