Re: [Harp-L] Double thickness reed plates? [getting long]

[Vern <jevern@xxxxxxx>]

It is true that the shorter reeds do not emerge on the back side of the reed plate.  That isnât a necessary condition for the reed to be a mechanical oscillator.  One puff per cycle still makes sound.  You push a child in a swing only at one end of the arc, then he âcoastsâ through most of the cycle. In a short vibrating reed, that brief pull occurs when the reed is above the plate and air is flowing through the slot. 

My main point is that it is not the static breath pressure but the bernoulli effect of flow past the reed that agitates it. However, the breath pressure causes the flow to occur.  IF there is insufficient gap, the static breath pressure pushes the reed into the slot and holds it there.  Thus it âchokesâ and there is no vibration.  When the reed enters the slot, it must have sufficient velocity (kinetic energy) to complete the half-cycle in the slot and emerge again to feel the down pull of the flowing air. When the reed is at the extremes of its displacement, its energy is potentialâstored in the bending of the metal.  As it passes its at-rest point, its energy is kinetic stored in its moving mass.  

Vern

> On Apr 8, 2016, at 1:11 PM, Larry Youmans <slyou65@xxxxxxxxx> wrote:
> 
> Interesting discussion but I must question how accurate some statements/ theories are.  Consider just how little of the reed actually comes through the reed plate, then explain how any certain reed can reach all the way through two thicknesses, especially the short reeds.  I can understand, and measure, long reeds reaching through both thicknesses, but the short reeds do not swing all the way through.  While playing exposed reedplates off my harps 
> I cannot feel the short reed come thru with my tongue!  I do plan on building a 364 double reedplate soon.  
> Sent via Mini iPad 3 
>