[Harp-L] Are different overtones available by changing reed shape?

[Robert Coble <robertpcoble@xxxxxxxxxxx>]

Has anyone experimented with changing the basic reed shape in 
order to change the set of overtones which are produced, or to
emphasize specific overtones, thereby changing the timbre of
the harmonica?

I don't have any machinery for trying some of these ideas, or I
would try first and report the results. (So many things I'd love
to experiment with, but not enough time and money... sigh.)

I realize that there are serious complications for trying to create
this type of thing for mass production. I'm just curious as to the 
effect (if any) that could be made on the overtones produced.

Or, perhaps the set of overtones is fixed by the very nature of
a free reed, regardless of the reed shape/design?

1. Try a reed with the reed tip rounded instead of square. The
reed plate would also have to be rounded to match.

2. Try a reed which is tapered (wide at the reed heel, relatively 
narrow at the reed tip), with a reed plate and chamber shaped 
similarly.

3. Try planing the sides of the reed slot so that there is no "lip"
for the reed edge to cut against. Think reed mounted to the 
chamber rather than to a reed plate sitting on the chamber,
with just enough clearance between reed side and chamber wall
to allow free movement, but with a small "lip" ONLY at the reed
tip to produce sound waves. Would that produce only a 
fundamental with no overtones?

4. Try putting "wings" (think of the shape as being similar to
a cross with VERY small cross beam) on the reed, with slots on
either side for the "wings" to cut through, as well as the usual
reed tip. Would varying the thickness and location of the "wings" 
along the length of the reed produce or emphasize different 
overtones?

5. Try a reed with a rounded "blob" (or other irregular shape)
at the reed tip. A variation is to use 2 or more lobes on the tip.

6. Try a very small pinhole (or a series of pinholes) in the middle 
of the reed which would leak a very small amount of air through 
it. I suspect this might change the available attack, but not 
change the overtones.

7. Try mounting the mouthpiece at right angles to the reed plate,
so that the air goes directly at the reed tip at a 90 degree angle, 
rather than sliding along the reed almost in the same plane as 
the reed.

Thanks,
Crazy (isn't it obvious?!) Bob
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