Re: [Harp-L] Reed design question.

[Vern <jevern@xxxxxxx>]

I'm guessing that the reduction in width of the high reeds was not for the purpose of reducing airflow.  As you say, all high-pitched reeds require less flow.   It may have been to balance the sound output.  As you know, the high pitches contain more sound energy.  This is why the low C3 octave does not carry well.  Narrow .072" wide reeds in the high C6 octave have been used for a long time.  There could be other more subtle reasons that I don't understand.

When you shorten a reed, you reduce the moving mass at the tip and raise its pitch.  By adding solder you have restored the pitch but have changed the design (see my previous post) to create a very stiff reed that responds poorly. This is because because it requires more breath pressure.  I suggest that instead of adding solder, you reduce the thickness near the rivet, approaching more closely the conventional design of the shorter reed.

Either by analysis or by trial-and error, harmonica manufacturers have had about a hundred years to arrive at optimum reed designs.  They vary very little from manufacturer to manufacturer.  We depart from that optimum at our peril!  It is a bit like marine technology....you should think a long time before you change something that has survived thousands of storms.

Hysteresis or loss of energy is a property of the metal which you have not changed.  Because solder at the tip does not bend, it doesn't absorb energy. I doubt very much that your problems arise from the metal behaving like a plastic.  If you added solder to the base of the reed (where it bends) to raise the pitch, it could absorb energy.  

Vern

On Apr 20, 2012, at 12:39 AM, Zombor Kovacs wrote:

> I am wondering what is the point making high pitched reeds narrower. I understand that if you increase the circumference at the same length it will increase flow cross section area, but at high pitched reeds much less air passes through anyway. While you can blow your lungs into a low reed, you can only blow a fraction into a high reed which - according to me - is not that comfortable. Why is it a good idea to reduce air quantity for high holes even more when it should actually be increased?
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> Another thing  what I experienced is response, which I put in relation with material properties. Sometimes I replace reeds for thicker reeds without knowing it. I only see it is the same length, so it will be fine. But what happens before I start tuning it is that suddenly the replaced reed has a much higher pitch than I expected and I have to put a lot of solder on it. Then after tuning it will have the right pitch but it will sound flat and unresponsive. My feeling is that it is the hysteresis what you get between a loading and unloading cycle. If you have a thick reed the thicker it is the more it will behave like a plastic material, which means that there will be a loss of energy inside the reed material. I don't know if anybody can confirm this theory. 
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