[Harp-L] My Omni-bender

[Paul Bowering <paul_bowering@xxxxxxxxx>]

Hey folks. I'm an occasional poster but a new job
without 'net access has prevented any contribution for
awhile. In the interim I've had time to think about
harp mechanics. I was trying to create an instrument
that has dual reed bends on both Blow and Draw on all
holes. I know; it already exists in the XB-40. I was
after a regular size harp with traditional tonality.
What I came up with takes from both the XB and
Discrete Comb concepts.

It occurred to me that if an auxilliary reed could be
added on the vertical plane then the increase in size
wouldn't be cumulative as with the XB-40 which adds
reeds on the horizontal plane.

The second discovery (perhaps old news for many of
you) is that Blow plates can function fine as Draw
plates and vice-versa. What I mean to say is that
affixed plates with reeds to the outside of the comb
chambers will function as draw plates regardless of
whether the reeds are riveted closer to the
front(mouth) side of the plate or the rear side.
Similarly a plate with reeds to the inside of the
chambers will function as a Blow plate. I don't wish
to say that orientation of the rivets has no effect
but it is certainly minimal in comparison to being
'inside or outside' the comb chambers. This second
tidbit was important because it removed the need to
fashion plates with some reeds riveted at the front
and others riveted toward the back.

To make the harp all that was needed was an extra comb
and one extra reedplate. It's neccessay to use a Blow
plate from a second harp to fashion the auxilliary
plate. This is because the rivets in the Draw plate
will prevent it from sitting flush against the comb
that doesn't have the divots carved from the wood.
(This consideration concerns the rivets' placement in
the vertical plane and doesn't contradict my earlier
point about the rivets' orientation not being of
consequence). Simply tune the auxilliary reeds a
semitone lower than the note you wish to bend down to
for each individual hole. I like to start with a Blow
plate that's a minor third down from the key harp
you're making. Also, be sure to set the auxilliary
reeds' with gapping that is flush with the plate.

 The finished product looks like a club sandwich or a
Big Mac. From top to bottom: original Blow plate;
comb; auxilliary plate; comb; original Draw plate. The
length and width are the same as a standard diatonic.
The height can be reduced by sanding down the combs. 

The good? It works! The middle plate can be considered
to be floating. With normal play you have air hitting
the bottom and top of the reed simultaneously. This
prevents it from vibrating and thus removes it from
the equation. You can do regular bends. By isolating
either the top or bottom row the auxilliary reed come
into play. Perhaps redundant but available are the
crisp overbends. It basically functions like the
Discrete Comb but Blow bends 1-6 and draw bends 7-10
are smooth dual reed, blues bends rather than the
single reed, 'valved' style bends.
Of course, some adjustment of technique is required to
get the missing notes but this can be incorporated
slowly and as needed. For regular play your mouth can
cover both upper and lower rows.

The bad? The height, for a couple reasons. First, it
was a surprise how hard it was to sand down the combs'
heights and maintain a level, flat surface area. I
sand all my Marine Band combs to remove imperfections
but taking this much material off and and alighing
screw holes was a real challenge. At least for me.
Secondly, making the chambers too small reduces volume
and response. The same is true of the Discrete Comb. I
think my concept can be a bit shorter than the
Discrete Comb because the auxilliary reeds, even at
zero offset, don't entirely seal off the upper row
from the lower. I had hoped this would allow the two
individual chambers to function like one regular sized
chamber. This may be somewhat true but still there's a
limit to how much you can reduce the combs' height.
You can't simply make combs that are 50% shorter than
normal without sacrificing volume and response.

Also, you can only really make these from Marine Band
style construction harps. For those who like recessed
plated and smooth platic combs I don't see how it
could be done with existing parts.

Like everything else this idea won't be for everyone.
Probably not even myself; getting the combs in good
shape was too frustrating and I've gone back to
half-valved diatonics. I don't even know if this has
been done by others and I'm just retreading old
ground. It was a fun experiment and I just put it out
there in the hopes that someone might refine the
process and maybe build on the concept.

I hope my writing was understandable and of some small
interest. Thanks to Tim Moyer for supplying me with
spare combs to mess with.

Paul B.




 
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