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highest hole response

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spectr:
Hi all.

As I understand there is a problem with highest holes on different chroms from different manufacturers, so play those notes require much effort than any others.
Recently I did rebuild of my 'Solo C' 12-hole harp to 'SLIPPY LC' by bolts and nuts with a new reeds. Before that 12th hole has decreased responsibility, and now I can play smoothly the whole range and those highest notes (G#6-B6) is problem no more. After that I rebuild holes 9-12 on my other harp in the same way - and highest notes (C7-D#7) plays just perfectly. So, after those rebuilds my harps are now solid in full range.

Now I believe that the source of problem is riveting, when the base of reed is bending along the reed and that cause flexibility decrease of reed, so much effort should be apply to play them; and highest notes are affected more because they are thin.

May be that information can be helpful to someone else.

P.S. Thanks to Roady43, I was inspired by his photo of half-assembled with screws augmented harp.

triggerfinger:

--- Quote from: spectr on October 01, 2010, 02:44:37 AM ---Now I believe that the source of problem is riveting, when the base of reed is bending along the reed and that cause flexibility decrease of reed, ...

--- End quote ---

Hi spectr

Would you please explain that again. This sounds interesting.

spectr:
Hi triggerfinger.

In attachment is a chart of proposed explanation. AD is edges of reed base, BC is cut of free part of reed; left image have directions of forces applying in riveting time, center - reed profile before force application, right image - after. Reed overlies on the reedplate.

After unriveting I've tried to assemble those reeds with bolts and nuts, and result was bad - reeds was deformed at unriveting time (I did unriveting in old fashion with hammer). But absolutely new reeds works well. So the only change is replace of riveting process to screwing, and the obvious explanation of seen phenomenon is reeds deformation. That looks logical to me.

Ribcracker:
It makes perfect sense to me. A riveted reed is stressed and distorted at the point where it's attached to the plate. Obviously, that system of attachment works fine with most reeds but it's easy to see how there could be inconsistencies across the board.
Attaching reeds with bolts would preclude "squishing" or displacing any metal thereby allowing them to resonate true.
This may be a poor analogy but I think if you took a pair of pliers and crimped a guitar string it would then not ring as true.

triggerfinger:
Spectr

I like the way you are thinking. If the reed was distorted in the manner depicted one could certainly expect an effect on the pitch and possibly the response but was the reed actually distorted? Next time somebody complains of having a high reed that isn't sounding or has bad response maybe we should recommend that they examine the reed base for this bend. Magnifying glass should do it.

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