Re: [Harp-L] Re: Changing a reed's length and thickness

[Music Cal <macaroni9999@xxxxxxxxx>]

I wonder how much the distribution of overtones will change with example
configuration given by David.


On Wed, Jul 9, 2014 at 10:43 AM, Vern <jevern@xxxxxxx> wrote:

> The pitch of a reed is proportional to the square root of K/M where K is
> its stiffness and M is its mass near the tip.  Stiffness K is affected by
> length and thickness near the rivet where it bends.  Its responsiveness to
> your breath depends on its stiffness K and its surface area.
>
> If you shorten a reed to move it to a higher & shorter slot, its pitch
> will go up and its responsiveness to your breath will decrease.  Then to
> restore the pitch and responsiveness, you will have to remove material near
> the rivet. Within the outline of an optimally-designed reed lie the
> outlines of smaller, higher-pitched reeds.  If you know what to remove, you
> can usually sculpt a higher pitched reed from a lower-pitched one.
>
> This will not greatly affect its fatigue life unless you remove the
> material in too localized a part of its length and create a stress
> concentration.   Pitch and responsiveness limit the ranges over which you
> can change the geometry.  Optimum designs have been determined
> experimentally over the years and any radical departure from them will
> produce disappointing results.
>
> Vern
>
> On Jul 9, 2014, at 7:50 AM, David Pearce <harpdog123@xxxxxxx> wrote:
>
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> > I've been testing some different harmonica designs using sydel's
> configured plates and I would like to know what the effect of changing a
> reeds length and thickness would be.  Let's say you have a G note for a 2
> hole draw.  What would be the effect of moving that G to a 3 hole draw and
> what would be the effect if you moved that G to the 1 hole draw?  I would
> think that increasing the reeds thickness by moving the G to hole #3 would
> shorten the reeds life since a thicker and less flexible reed would be
> vibrating vs a thinner and more flexible reed.  What would be the effect on
> the reeds tone?
> >
> > David Pearce
> >
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