Re: [Harp-L] Bending Stress in reeds (was Manji Reed Quality)

["Rick Dempster" <rick.dempster@xxxxxxxxxxx>]

Correct Arthur. See my recent post to this same post of Vern's. I was avoiding mentioning 'overblows'.
A single reed can be flattened a long way, but if it's pitch comes close to the 'reverse' pitch of it's pair, then the paired reed will take over. The D (drawn) note on hole 1 of a C harp will pull down towards the  pitch of the C 'blow' reed, which already is moving in sympathy with the air and the overtones of the higher reed. When the D is flattened close to Dd, the drawn pitch of the blow takes over. 'Overblowing' is no different to 'conventional' bending. It's just harder because you can't go to it gradually (which is in part why 'overblowers' like it too)
I sometimes show my students a bicycle horn, with it's single reed which is both blown and drawn to produce the two pitches.
Still the question remains:Why is it so?
RD

>>> Arthur Jennings <timeistight@xxxxxxxxx> 23/11/11 9:42 PM >>>
I think Rick is asking about overblows.

If you overblow hole six on a C harp, the blow eed chokes and the draw reed
sounds, but it produces a note (Bb) one semitone higher than it does when
you sound it by drawing. Why is that?

On Wed, Nov 23, 2011 at 12:20 AM, Vern <jevern@xxxxxxx> wrote:

> Unless it is excited by the closing reed in the same chamber, the opening
> reed won't sound at all.  If it is excited by the closing reed, (as by
> bending in a diatonic) during diatonic bending, the pitch is between the
> pitches of the two interacting reeds.
>
> Vern.
>
> On Nov 22, 2011, at 9:36 PM, Rick Dempster wrote:
>
> > What's always escaped me Vern, is why a reed plays a semitone higher
> when it is played with the reverse breath - ie a draw reed played with a
> blow, or vice versa. Any clues?
> > RD
> >
> > >>> Vern <jevern@xxxxxxx> 23/11/2011 16:27 >>>
> >
> > On Nov 22, 2011, at 4:12 AM, Tom Cox wrote:
> >
> > >  ........I dont wail and hammer notes with excessive
> bending.................
> >
> > The assumption that bending puts extra stress on reeds seems ubiquitous
> among harmonica players..
> >
> > Although extra effort on the part of the player is required to establish
> the embouchure resonance to bend the pitch, the analogy that extra stress
> on the player creates extra stress on the reed may not be warranted.
> >
> > The stress in any reed is purely a function of its vibrational
> amplitude.  In bending, it is not obvious that either reed vibrates at a
> greater than normal amplitude.  I think that it is very likely that
> amplitude is greatest when the embouchure resonance is the same as the
> un-bent natural resonant frequency of the reed.
> >
> > I looked again at Dr Bahnson's video on bending.  It shows the reeds as
> bending takes place. Although I didn't see any extreme deflections, the
> pictures were not easy to interpret.
> >
> > Vern
> >
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-- 
Arthur Jennings
http://www.timeistight.com