Fwd: [Harp-L] Basic Overblowing question

["Winslow Yerxa" <winslowyerxa@xxxxxxxxx>]

--- In harp-l-archives@xxxxxxxxxxxxxxx, "samblancato" 
<samblancato@xxxx> wrote:
Guys,

I am not that swift on all the issues surrounding overblowing.  It 
would
help me a lot if someone could explain to me what notes overblowing 
gives
you on, say, a C harp that arent there.  What scales do these notes
complete? 

Rather than direct you to an external site, let me just briefly 
recount the main point, if for nothing else than for future archive 
divers.

Overblows and overdraw (overbends) provide several issing notes that 
allow the diatonic harmonica to produce notes not produced by other 
means, thus allowing for a complete chromatic scale.

Overblows and overdraws are not to be confused with the blow bends 
available in in the top four holes of a standard diatonic - those are 
dual-reed bends, as are the draw bends in HOles 1 through 6.

Dual-reed bends lower the pitch of a note. For instance, Draw 2 on a 
C harmonica produced the note G. G can be bend down continuously in 
microtonal increments as far as F-natural, or two semitones, or a 
semitone above the blow note in the same hole, which is E. (actually, 
it will bend to a note that is flatter than F but sharper than E - 
this flatness at the bottom of a bend is characteristic of all 
standard bends on a standard diatonic).

For each hole in the harmonica, the higher pitched of the two notes 
will always bend down to within a semitone of the lower-pitched. Both 
reeds participate in making the bent note sound, and the range of the 
bend is limited to the notes occurring between the pitches of the two 
reeds. Hence the term "dual-reed bend."

In an overbend, the higher-pitched reed in the hole goes UP in pitch. 
The note is created by making the reed vibrate backwards. Instead of 
being pulled into its slot and springing back (closing), it is 
instead pushed AWAY from its slot before springing back (opening). 
This produces a pitch slightly less than a semitone higher than the 
default pitch of the reed.

Making a reed go backwards also means using the opposite breath 
direction. So an overblow is produced by blowing and making the draw 
reed sound instead of the blow reed. You can see that making the blow 
reed fail to respond to a blow breath involves some technique. The 
technique is just an application of standard bending technique. Turn 
this around for obverdraws in the top four holes.

In many ways, overbends are the miror image of dual-reed bends. Draw 
bends occur in Holes 1-6, and so do overblows. Blow bends occur in 
Holes 7-10, and so do overdraws.

Look at a tuning diagram for a C-harp. Draw in all the dual reed bend 
you already know. Then draw in notes one semitone above the draw 
notes in hole 1-6, and one semitone above the blow notes in Holes 7-
10. You'll see how the overbends supply all the missing notes of the 
chromatic scale, plus a couple of duplicate notes.

Winslow