Re: [Harp-L] triple vs quadruple reed harps

[Zombor Kovacs <zrkovacs@xxxxxxxxx>]

Sorry, I did not quite grasp the concept here:

"In 2003, I conducted an experiment in which Iincrementally retuned the pitch of an accordion reed over a range of nine
semitones, measuring its effect on the pitch of the opposing reed in its
chamber. "

Which was the blowreed and which was the drawreed? 

Zombor



________________________________
 From: Rick Epping <rickepping@xxxxxxxxx>
To: harp-l@xxxxxxxxxx 
Sent: Saturday, September 15, 2012 6:20 PM
Subject: Re: [Harp-L] triple vs quadruple reed harps
 
In regard to Richard's observations, the sole purpose of the XB-40's
internal valves and valve chambers is to isolate the auxiliary reeds from
all reeds playing in the opposite airflow direction, with which they might
otherwise sympathetically play when not wanted.  Indeed, this is the basis
for my patent, as stated in the following relevant section:

"The use of a single auxiliary reed mounted flush over a slot in a cell for
bending has been suggested before this invention and no claim is made to
this invention.  However, such feature is unsatisfactory when multiple
adjacent cells are used in a harmonica because of undesirable sympathetic
vibration of reeds in adjacent cells. The use of enabler reed valves
eliminates this problem and makes possible the improved harmonica of this
invention."


I believe that the unusually high longevity of the XB-40's reeds is
due partly to
its comb design, which forces the airflow through the valve slots before it
reaches the reeds, thereby creating the Venturi effect of both reducing the
airflow's pressure while increasing its speed.  This reduction of air
pressure on the reeds should help prevent their being driven past their
elastic limit.


Winslow's point that each normal reed has a responder, or auxiliary reed to
act as a shock absorber is also valid.  And it's not simply that the
auxiliary reeds act as shock absorbers.  I tend to believe that playing a
reed in an environment which allows it to oscillate closest to its natural,
or plucked frequency, is less likely to stress it than in other, less than
optimal environments.  In 2003, I conducted an experiment in which I
incrementally retuned the pitch of an accordion reed over a range of nine
semitones, measuring its effect on the pitch of the opposing reed in its
chamber.  I found that the opposing reed tended to play at its highest
frequency - that is, closest to its natural frequency, when paired with a
reed tuned lower than itself.  I conducted a similar experiment at this
time, where I tested the performance of a harmonica's draw reeds when
mounted with blow reed plates from various keys ranging from lower to
higher than that of the draw reed plate.  Once again, the draw reeds
performed best and played at their highest frequency when matched with blow
reeds tuned lower than themselves.  Better even than when they were matched
with reeds tuned to the same pitch and better than when the opposing reed
was isolated from the airstream by a valve.  This phenomenon can also be
noticed on a standard, un-valved Richter harp, where the draw reeds in
holes 1 through 6, which are paired with reeds tuned lower than themselves,
play more easily and require less offset relative to their
flexibility and pitch than do the draw reeds in holes 7 through 10, which
are paired with reeds tuned higher.


Best regards,

Rick


> ------------------------------
>
> Message: 3
> Date: Fri, 14 Sep 2012 22:10:28 -0400
> From: Richard Sleigh <rharp@xxxxxxxxxx>
> Subject: [Harp-L] triple vs quadruple reed harps
> To: harp-l@xxxxxxxxxx
> Message-ID: <27C9CA42-B0C9-4EB5-A05E-6E65348FAD08@xxxxxxxxxx>
> Content-Type: text/plain;       charset=us-ascii
>
> One of the things that makes the SUB 30 a lot more like a standard
> diatonic is that the three reeds all share the same chamber. In the XB 40,
> there is a separate chamber with the valves in it that directs the air to
> additional chambers that each have  two reeds. This results in the extra
> thickness of the comb. It also creates different internal acoustics, so the
> tone of the harmonica is, to my ears, unique. It has some of the qualities
> of a chromatic & some of the qualities of a diatonic, but also a sound all
> it's own.
>
> With the XB 40, your breath takes a more circuitous route before it gets
> to the reeds. I think one reason why they last longer is the extra distance
> between your breath and the reeds, as well as the constrictions that the
> air must go through, creates a buffer zone that shields the reeds from
> extremes of attack. Plus the XB 40 is naturally louder because there is
> more resonant space to boost the vibrations. Just like the same string on a
> guitar with a big body sounds louder than if it were on a small body guitar.
>
> With a smaller harp, the tendency is to hit it harder to make it louder,
> and the reeds are getting a direct hit from your breath.
>
> One thing that will take some new techniques and general getting used to
> on the SUB 30 is this: the way you play it can cause the extra reeds to
> play sometimes when you don't want them to. Three reeds. one wind-saver,
> means that part of the time you have two reeds in play and one cut off by a
> wind-saver. The rest of the time you have three reeds exposed to the
> breath, and one of them rests in the slot to resist the air flow. This
> third reed can break free and start vibrating under the right conditions
> (well, really, the wrong conditions - cause you don't want this to
> happen...) It could be the bending embrochure supporting an overtone or
> vibration that is close to the pitch the reed is tuned to, causing it to
> start vibrating.
>
> I am learning where this happens, and it is either during a bend with a
> lot of air pressure, or if I play the wrong chords or double stops. So
> finessing the air pressure and embrochure is part of the learning curve.
>
> I believe that a combination of playing technique and reed set-up will
> eliminate these problems, but it will take some time to sort out, and will
> be different for different keys.
>
> Richard Sleigh
>
>
>