XB-40 in C has this squeal problem

["Jr Bliggins" <JrBliggins@xxxxxxxxxxx>]

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About six months ago I hand built my own XB-40 because I just couldn't =
wait any longer for distribution.  I experienced the same problem.  Does =
the squeal sound like two notes beating slightly out of phase? It isn't =
really the same single reed cross tensional squeal we sometimes hear =
when learning overblown notes.

  I believe it is caused by the enabler reed in the adjacent hole =
vibrating in sympathy with your target note when it is bent. For =
Example:

I have the problem in the high notes but I also experienced the problem =
on the 3 and 4 draw.  My "C" XB-40 Harp was set up with one step bends =
on each hole, not the two step bends that Rick's design has.  Hence the =
enabler reed for th hole 4 blow was tuned to "B".  Causing a half step =
bend from "C" to "B" on 4 blow.  When I bent both draw holes 3 and 4 at =
the same time, the normal "B" in hole three draw would intice the "B" =
enabler reed in 4 blow into vibrating in sympothy even though I was =
drawing.  (remember the offset is at zero).  The nasty squeal was the =
result when I bent the "B" down the two notes began to beat.  I retuned =
the enabler reed to "Bb" and the problem for the most part went away.  I =
orginally thought that was why Rick's design uses whole step bends =
through out.  But then I talked about this issue with Rick at the NY =
gathering last spring, and he said he solved the problem by having the =
reeds completly isolated from each other within the comb design.  I have =
not seen the structure yet for my self nor have I tried the factory =
XB-40. =20

I guess I have digressed a bit with this back ground information.  But =
my advise is to try to use a technique where you very carefully hit your =
target note without allowing any air into the adjacent hole.  Then the =
un-desired enabler reed will not be excited into sounding. Often in =
actual playing situations I allow some air to leak into the adjacet hole =
before I quickly lock down on my target note.  I do this unconsciously =
in some situations to add a little texture to the note.  Perhaps on an =
XB-40 I have to un learn this habit. I don't know if this is your =
problem but see if it helps, it seemed to work for me on my hand built =
XB-40.

Jr. Bliggins