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Date: Thu, 19 Apr 2001 09:58:41 -0700 (PDT)
From: Winslow Yerxa
Subject: [none]

Brother Vern searches the heavens for a sign:

>The technique of reed gapping seems to me to be one
>of intense interest to all harpers. However, there
>seems to me to be very little published,
>authoritative information. I have the impression
>that those who do it really well hold it as a trade
>secret. My knowledge of harmonica technology is
>weakest in this area.

>A properly-gapped reed is very responsive and
>performs well.

Responsive to whom? and for what desired reed
behaviors?

It is well known that a higher gap resonds to a
forceful attack, but not to a light attack, while the

opposite is true of a lower gap. Either one can be
desirable, depending on individual technique, and on
the requirments of a particular style.

By way of example:
I remember when you had a pressure gauge at SPAH to
measure pressure increases when players bent notes.
Jerry Portnoy hit his bends hard - as a matter of
Chicago blues style and not one of technique - and
made the meter jump. he'd be a candidate for higher
gapping. As a player with more of a jazz and quasi-
legit attack, I was able to keep the meter dead even
while bending - I'd be a candidate for lower gaps.

It goes beyond style, however. It also becomes a
question of what you want the reed to do. In the area

of note bending, for instance, closing reeds will
bend farther with a higher gap, while opening reeds
will initiate more easily and bend farther with a
lower gap - there are trade-offs, depending on what
you want.

>However, there should be clues about the geometry
>and "look" of the reed and gap that predict and
>produce the good performance.

They will predict and produce a whole variety of
behaviors that may or may not be "good," i.e.
desirable, depending on what the player is looking
for.

>Are there experts out there who are willing to
>address the following questions in detail?

By their works shall ye know them. But they may not be
especially talkative. However, their works may be
examined, if you know what to look for. There are some
obvious things that may be useful to examine:

- gapping at the tip

- gapping at the base

- profile of the reed rising from base to tip

- alignment of reed edges with slot edges
(hold the reedplate up to a light).

- tolerances between the edges of the slot and those
of the reed.

- lateral alignment of the reed with the reedplate
(is the left edge higher or lower than the right?)

- relative gapping of the right and left edges of the

reed

- regularity of surface along length - no bumps or
"wrinkles"

There may well be tiny subtleties that these pointers
don't address.

>Q. Have I missed an obvious source of information on
>the subject?

Steve Baker's Harp Handbook has some good basic
information, as do Blackie Schackner's books (I can't
remember what Doug Tate's books have to say on the
subject). But the biggest repository of written
information on the subject is right here at harp-l in
the archives. Some of the questions you ask below are
addressed.

>Q. What is the correct shape of the reed; straight,
>curved, etc? If curved, what radius of curvature?

The consensus seems to be that curvature should be
minimal, just enough for the reed to rise from the
base to the tip to create a sufficient gap. It should
look almost straight. Sufficient gap? Rule of thumb is
that the gap should be about equal to the thickness of
the reed at its tip.

If the rise of the reed involves even a slight
curvature, it still could not be quantified as a cut
and dried radius because reeds vary in length. A gap
produced in this manner may have no consistent
relation to the primary gauge of the gap - the
thickness of the reed's tip.

>Q. Should every length of reed have its own optimum
>gap shape? If so, are they known and can they be
>published?

Ah. There you may be encroaching on the the arts of
the Guild. But I can offer a few observations.

Aside from the problem of what constitutes a good gap
for whom and for what purpose, there is also the
matter of weight distribution. Heavily weighted reeds
(those with increased thickness at the free end) can
take a stronger attack to shift, and hence may require
a bigger gap than reeds of the same length with less
weight at the end.

>Q. What tools are most often used by the experts to
>set gaps?

Joe Filisko and Richard Sleigh have done seminars on
reed adjustment that included tools - I recall one
extensive one at Buckeye a few years ago. I couldn't
attend as I was doing a soundcheck for our concert,
but many harp-l'ers did attend and some could perhaps
fill you in

>Q. Has anyone succeeded in measuring the gaps and
>curvatures of reeds that perform well?

If they have, they're not telling. I suspect Hohner
has done considerable research, in addition to all the
independent techs.

>Q. Is there a theory of gapping that explains why
>some gap shapes work better than others or is
>everything entirely empirical?

I believe you could find some helpful information in
Robert Johnston's paper. He examined gapping, if I
recall correctly, and confirmed what most players know
empirically - that a high gap responds to a hard
attack but not a soft one, and a low gap vice versa.
There may be additional information that would be
helpful.

>Q. Would it be possible to have a SPAH01 seminar by
>several recognized experts devoted entirely to
>gapping? Would anyone attend but me?

I think it would get a huge attendance!

>Q. Are these even the right questions?

They're a subset of them.

One thing you haven't examined is what constitutes a
"good" gap. This varies considerably with individual
styles and with style of music. I've addressed that
above, in part. Here are a few more considerations:

Hohner diatonics often come out of the box with gaps
set incredibly high. This is done because beginning
players tend to use too much pressure when playing the
diatonic. The reed refuses to speak, and they try to
return as defective a perfectly good instrument - I
have witnessed this directly. To a non-beginner the
harp feels leaky. But from the retailer's point of
view, this is "good" gapping because it cuts down on
returns.

Many Filisko instruments have the action set so low
that even expert players unaccustomed to playing them
will choke out the reeds. Yet the player who has
learned to use a light attack can find a much wider
dynamic range and responsiveness from those same
reeds.

I think perhaps "gapping" is too narrow a term for
what is really overall reed adjustment - the integrity
and shaping of the reed itself, and all aspects of its
placement relative to both the reedplate and the slot.

I favor the term "action" as in setting the action of
a guitar. larry Eisenberg, a piano tuner by trade,
uses "regulation."

Winslow Yerxa

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