[Harp-L] Re: Reed Durability: The Facts/ Reed Chamfering

["Rick Epping" <rickepping@xxxxxxxxx>]

Hi Vern,

Your proposed reed testing machine is essentially the same as that used by
Hohner to test reed durability and pitch stability, down to the soundproof
room!  They sometimes call it a Blasmaschine (blow machine).

During one of my spells at the factory in the late '90s, I found that
Eberhard Glunz, Hohner's materials engineer at the time, had connected the
Blasmaschine to an oscilloscope and computer in order to measure reed
response time and volume.   He linked the switch that turned on the vacuum
to those of the oscilloscope and computer, which would then begin recording
the data the moment the vacuum was turned on.  The computer would produce a
graph, with the x-axis indicating duration of time in milliseconds from
activation of the reed and the y-axis indicating amplitude in decibels.  In
order to ensure accuracy, he programmed it to produce a graph showing the
average of any predetermined number of activations of the reed.

We used this system to test the technique of reed chamfering, where the
upper edges of a reed are broken (I use a small chisel to chamfer the
edges).  I attached to the Blasmaschine a Marine Band without covers, with
all but one reed taped off, and we obtained an average of ten activations,
measuring how many milliseconds it took for the reed to attain its maximum
amplitude, which can be considered its response time.  Then I removed the
harp, chamfered the reed and immediately replaced it onto the machine for
another ten activations.  This test was repeated for a number of different
reeds.  As I had already been chamfering the reeds of my own harps for some
time and had noticed through playing them an improvement in response time, I
had expected this to be confirmed in this test, and it was.  What was
surprising, however, was that there was not only an improvement in response
time but a marked increase in average maximum amplitude; chamfered reeds
were shown not only to respond more quickly, but to play louder.

Glunz said that this improvement in response and volume could not be due to
a change in the flexibility of the reed, as so little material was actually
removed, relative to the overall mass of the reed.  The improvement, he said
must be due to a change in the aerodynamics of the reed.  It would seem that
chamfering the reed's upper edges produces a similar aerodynamic to that
from a process of manufacturing high-end accordion reeds, where the upper
surface of the reed is milled while the reed is attached to a revolving
drum, producing a radius along the length of the reed, where the reed is
thickest along its middle length and gets thinner toward its long sides.

When hand-finishing harmonica reeds I usually emulate to some degree the
rounded shape of accordion reeds produced in this manner.

Best regards,
Rick



> ------------------------------
>
> Message: 4
> Date: Mon, 8 Dec 2008 13:50:31 -0800
> From: "Vern Smith" <jevern@xxxxxxx>
> Subject: Re: [Harp-L] Reed Durability: The Facts
> To: "Brendan Power" <bren@xxxxxxxxxxxxxxxxx>, <harp-l@xxxxxxxxxx>
> Message-ID: <C275A886B48A4A62BED2C386CDE12A41@user292e480637>
> Content-Type: text/plain; format=flowed; charset="iso-8859-1";
>        reply-type=original
>
> Thanks for that expression of confidence.
>
> It would not be an easy test to conduct because it would require a
> reasonably large set of each type of reed to be statistically sound.
>
> I would suggest that it could be done as follows:
>
> I would suggest that for each brand and type, it would require about 6 sets
> of identical diatonic reedplates.
>
> I would hot-glue all the reeds closed except the Gs in the low octave and
> the Es & Fs in the higher octaves.  I would consider the Es and Fs
> separated
> by a halftone to be part of the same cohort of 12.
>
> I would build a big platform that would hold all of the reedplates on a
> vacuum box.
>
> A vacuum cleaner tamed by a light dimmer or a variac could produce a vacuum
> of about 10 inches of H2O to work the reeds fairly hard.  The vacuum
> cleaner
> might have to be replaced because the reeds might outlast the commutator in
> the series motor.  A guage or manometer would be required to monitor the
> vacuum.
>
> The contraption would set up a terrible howl so would require a
> "soundproof"
> box that could be constructed of  multiple layers of wallboard.  Fluffy
> stuff like caneboard suppresses sound reflection but mass is required to
> suppress transmission.  The pump could not be placed in the enclosure
> because of heat build up.  That would also require construction of a pair
> of
> "silencers" that would allow passage of air but suppress the passage of
> sound.
>
> The reeds would be checked by placing rubber mats over all but the one of
> interest.  An electronic tuner would determine failure when a reed goes
> (TBD) cents flat.
>
> A timer switdh could run the pump for a measured period and then shut it
> down to wait for the operator to check the reeds at his convenience.
> Checking the frequency of that many reeds repeatedly would be tedious.
> Initially the timer could be set for short periods, then longer periods if
> the data warranted.
>
> Raw data would be the approximate time to failure of each reed.  They could
> be analyzed many ways but life expectancy is usually determined when half
> of
> a cohort has died.    This way the test could end when half of the
> longest-lasting set has died.
>
> I have thought about how to do this for some time.  Obviously, it is a
> daunting effort.
>
> Vern
>
> ----- Original Message -----
> From: "Brendan Power" <bren@xxxxxxxxxxxxxxxxx>
> To: <harp-l@xxxxxxxxxx>
> Sent: Monday, December 08, 2008 11:25 AM
> Subject: [Harp-L] Reed Durability: The Facts
>
>
> > The title of this post is a misnomer, because there are none - just lots
> > of claims and counter claims.
> >
> > I freely admit to making frequent claims that Suzuki reeds last the
> > longest, based on personal experience of many brands. Others say the
> > same regarding Lee Oskars, or Seydel stainless steel reeds. Hohner
> > didn't have a great reputation when it came to reed durability, but
> > Steve Baker is claiming that current Hohner reeds are now "extremely
> > durable" (Harp-L Dec 7th).
> >
> > It would be great to have a truly impartial test of reed durability
> > under strictly controlled conditions. Then the consumer would really
> > KNOW which brand and model is the best in this regard, rather than
> > having to rely on hearsay and players/manufacturers' claims.
> >
> > I can't think of anyone better than Vern Smith to devise and conduct
> > such a test. Maybe we should all contribute a few bucks each via PayPal
> > to someone like Vern to do a real hard-core test that would leave
> > everyone satisfied that fair play was strictly observed and justice had
> > been done to every brand.
> >
> > Will you take up the challenge, Vern? Or at least suggest a way to
> > proceed? I know this topic has been visited before, but the test is yet
> > to be done.
> >
> > Wouldn't it be great to know for sure? It would be good for all
> > manufacturers and the consumer: the winning maker would get great
> > publicity, and the losers would be encouraged to smarten up their act
> > before a subsequent test. In fact, it would be great to have such tests
> > every couple of years. We, the players, would be the winners.
> >
> > Brendan Power
> > WEBSITE:  <http://www.brendan-power.com/> http://www.brendan-power.com
> > YOUTUBE:  <http://www.youtube.com/BrendanPowerMusic>
> > http://www.youtube.com/BrendanPowerMusic
> >
> >
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>
>