[Harp-L] On reed problems

[Snaruhn@xxxxxxx]

 Hi,

on harp-L one can read a lot of useful things around the harp, technical,
as well as learning, playing or teaching aspects. Harp customizers offer 
sophisticated models or others talk about their efforts of soaking wooden 
combs with all kinds of curious mixtures.

All these things are important but all are in vain if the most essential harp
parts aren´t working correctly: the reeds.

I´m just making a CB 14 where I inserted Super 64 X reedplates. 
Unfortunately,I caught a couple with the actual crossed reed layout 
(about this weak point at the end).

Now, I´m just checking reed by reed for their optimal function and had liked 
to
mention some problems which are well-known but worth to talk about them
again and again.

Recently, we discussed about embossing the plate slots in order to diminish
the reed tolerances. Though Tim mentioned an interesting method to emboss
the slot sides by a cylinder, I really doubt that embossing achieves a 
noticable
improvement. The tolerance of a reed side to the slot wall is the thickness 
of
a razor blade = 0.08 mm and nobody can tell me that the human ear can
recognize a lesser tolerance. Above all,  a crucial check has to be done 
before embossing at all. 

The reed has to be absolutely centered and that´s the problem. My experience
is that almost 50% of the reeds are excentral (caused in the factory - mass
products as said). There are at least 3 possibilities to check the centric 
reed
position:  
 
1. The most precise way is the translucent light. It even works at valved 
reeds.
    Hohner´s "paper tigers" aren´t an obstacle.
2. When a reed is bent down the reed sides give a shadow at the slot sides.   
    
    If the reed is excentral the shadows are unequal, respectively, the reed
    edges are asymmetrically diving into the slot. 
3. A plugged centric reed has to produce a clear sound. If the sound is dull,
    muffled or chirping the reed is excentral. However, the plugging to check 

    the reed position has to be performed correctly. The reedplate must not
    be touched by the fingers because they muffle the vibration. Best is to 
put
    the reedplate on the table. To hear the clean sound of a centred reed the
    reedtip mustn´t be moved upwards but down to the plate.
    Optimal tools are medical scalpels in different shapes.

In most cases an excentral reed is only too close to the slot wall at the 
root, 
while the tip is free. So, in case, any reed is centric but the neighbour 
reed
isn´t most harp players won´t notice a difference but sensitive ears will.  

Well, sometimes it can happen that a reed is touching the slot further to 
the tip. Here, the roulette command goes, rien ne vas plus. Two reasons 
can be responsible. If the reed is "only" twisted around the rivet, it can be
turned back at the root by a respective tool. However, if the reed is 
excentral      
in its whole length, the rivet has to be loosened to shift the reed back.

I won´t forget to mention a further angry reason why a plugged reed doesn´t
give a clean sound besides an excentral position. That´s the way reeds are
tuned, specially, in the factories. Up to some years ago reeds have been 
tuned by scratching tools, files or scissels. Factory "tunas" have little 
time
to tune the mass products. So, one can see exactly how they do this job.
Sometimes not only the reed shows how the file engraved its track but
the plate is damaged too. 

The point is that the tuning file can move something of the reed edge 
down into the reed/slot tolerance, thus obstructing the free reed vibration.

How reeds have to be tuned correctly is a harp-L evergreen I won´t repeat.

Finally, some ideas to the actual crossed reed layout at chromatics. 
In former decades we had the straight reed system with the small slide
holes. That the bigger slide holes of the crossed reeds allegedly gives 
a better airstream to the reeds is nonsense. In the contrary, the bigger
holes cause "air gaps" when moving the slide, specially noticable at 
the higher notes and above all, the slide way is twice as long. For my
part I don´t hear any sound difference between my crossed and straight
CX 12s.

Siegfried