Re: [Harp-L] how much can a note be bent

[Winslow Yerxa <winslowyerxa@xxxxxxxxx>]

When the blow and draw reed are pitched too far apart, they no longer affect each other's bending range, so they start to behave more like isolated reeds. I did some casual experiments with this several years ago.

Let's say you have a blow reed tuned to Middle C (C4) and a draw reed tuned to G4. If the G reed will bend down to, let's say Eb and the C reed will, in opening mode, bend from C# up to E, then they will overlap enough to possibly allow for a continuous bend all the way down from G to C#. More overlaps between the reeds will help the bend be more stable and sound richer throughout its range. 

Real-life applications of wide tuning gaps that produce usable bends include a Lee Oskar tuning that, on a C harp, would tune the Blow C in Hole 1 down to Bb and the Draw D up to E. Carlos del Junco used this successfully on his recording of B-Thing. Also, in a Hohner 364 diatonic (12 holes), Hole 12 has Blow G6 and Draw D6, allowing for a smooth blow bend all the way down to Eb6. 

However, beyond a certain point, you're just not going to get two reeds to bend far enough to overlap or even meet. While six semitones (as in the Lee Oskar example) seems well within the pale, I suspect the range of seven semitones may be close to that limit. An octave seems to be quite outside it. At that point, the blow and draw reeds will act like isolated reeds.

The bending range of an isolated reed (as in a chromatic harmonica) depends partly on gapping (wider gap allows for wider bend), player skill, and may also be affected by the flexibility of the reed. One aspect I didn't investigate in my experiments was the role played by air leaking through the opposite reed. Having an alternate source of air access will act as a shock absorber, allowing a stronger attack on a reed in an unvalved pair than in an isolated reed, but I don't know how it would affect bending.

So let's say you can get four semitones in bending range out of a reed. You set up a 1-hole harmonica with a draw reed that plays C5 and a blow reed that plays C4 - the two reeds are an octave apart. 

Can you bend the draw reed down four semitones? That will depend partly on reed gapping and player skill. It may be affected by the fact that air is leaking through a reed that can't respond and participate by vibrating at the same frequency because it's just pitched too far away.

Can you get the blow reed to bend down in pitch? It's no longer locked in a system with the draw reed, so it might be possible.

What about getting the reeds to act in opening mode (overdraw on the blow reed, overbow on the draw reed)? All these behaviors are potentially possible if the presence of the other reed (and its attendant air leakage) does not interfere with the reed's ability to act as if isolated.

Winslow

Winslow Yerxa

Author, Harmonica For Dummies ISBN 978-0-470-33729-5

--- On Mon, 12/7/09, Avery Man <elfrex@xxxxxxxxxxx> wrote:

From: Avery Man <elfrex@xxxxxxxxxxx>
Subject: [Harp-L] how much can a note be bent
To: "harp-l" <harp-l@xxxxxxxxxx>
Date: Monday, December 7, 2009, 6:27 AM


i know it's about a semitone higher than the lower of the reeds. but is there an interval limit with blow or draw? ie: say i had a blow C4 reed a short C5 draw reed in one hole. can I draw bend the C5 note down to a C#4? could i do a wider interval (say between C4 and C6?) How does it behave in various octaves?
                           
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