[Harp-L] Re. New Twin-Diatonic Harps

[bren@xxxxx]

Rick Dempster wrote re. my X-Reed UniBender (which uses two diatonics behind
a single mouthpiece to create an all-bending harp):

 

".I can't work out how Brendan has set this up. It sounds like he is using
one harp for the blows, and the other for the draws.
But knowing that the 30 reed harps have to top four blow reeds on the draw
plate, I can't quite see how that could be easily done."

 

The SUB30 is what I call a "triple-reed x-reed type": 3 reeds per chamber,
two active reeds and one x-reed. The x-reed, set with zero gap, is pitched
below the lowest of the active reeds to allow it to bend. In this case, a
valve on the reedplate cuts out the highest-pitch reed, allowing the lower
one to bend. But on the opposite breath, the bending is the standard type as
on any diatonic: the highest of the two active reeds will bend down to the
lowest one via interactive reed bending.

 

To give an example: On hole 4 in key of C, you have the blow C and draw D
active reeds. A valve is fitted on the draw reedplate to stop air to the D
draw note when you blow. When you draw it lifts up, allowing the D and C to
interact and get the bend down to C# - as normal on any harp. 

 

But there is a third draw x-reed fitted on one of the reedplates, which is
pitched at least a tone lower than the C (it could be tuned to anything you
want, but let's say Bb for this example). When you blow, the valve closes
over the D and only the blow C and draw Bb x-reed are in the airflow. This
allows the blow C to bend to B. 

 

This pattern repeats itself throughout the SUB30, even in the reversed top
octave in Richter tuning - though in that case the x-reed is an extra blow
to allow the draw notes to bend. 

 

Because there are 10 holes, this triple-reed type has 30 reeds - hence the
name SUB30. In Richter tuning, it can bend 8 reeds in the standard way as on
any harp (1,2,3,4,6 draw, 8,9,120 blow), and they bend to the same pitches
as on a standard C harp. But it has 10 extra bends (blow 1-6, draw 7-10).
These are determined by the pitch of the x-reeds, and so the bends can be
altered according to what you desire. There are still to notes that can't
bend in Richter tuning: 5 draw & 7 blow.

 

My twin-diatonic X-Reed UniBender is a different type: a "quad-reed x-reed
harp". Like the Hohner XB-40, it has 4 reeds per chamber: two active reeds
and two x-reeds - 40 reeds altogether in 10 holes. In the quad-reed type,
there is no interaction between the two active reeds: all the bending comes
from interaction of the active reeds with their paired x-reeds.

 

This is determined by valves. The XB-40 has 20 valves inside the comb,
affecting airflow before it hits the reedplates. My UniBender works on the
same basic principle, but works differently:

 

1.	Instead of two 10-hole chromatic-type reedplates on a single comb,
it uses two diatonic harps to supply the 40 reeds - 4 reedplates altogether,
on two combs.
2.	Instead of 20 separate valves inside the comb, I have developed a
single one-piece valve strip that fits in the mouthpiece. This has short
wide valves, which determine what air goes to each separate harp: blow, and
one harp sounds; draw, and only the second harp sounds. 

 

In the example on the video, the top harp has the blow active reeds and
their zero-gap draw x-reeds - this harp gives the blow notes and blow bends.
The bottom harp has the draw active reeds and their zero-gap blow x-reeds
this harp gives the draw notes and draw bends.

 

The advantage of the quad-reed types is that:

 

1.	Every reed can bend, regardless of the pitch difference between the
two active reeds. That includes 5 draw & 7 blow in Richter tuning.
2.	You can tune all the x-reeds to anything you want to get whatever
bends you desire, on every note! 

 

The x-reed is always pitched a semitone lower than the bend you want to
achieve. If you only want a semitone bend, the x-reed should be pitched a 2
semitones below its paired active reed. If you want the bend to go down 2
semitones, then pitch the x-reed 3 semitones down . and so on.

 

The principle is the same as the XB40, but obviously the size of the
UniBender is smaller, and the tone is closer to that of a standard 10-hole
harp. Plus you have the ability to quickly swap in different keys/tunings to
the same frontal mouthpiece, using the rear screw fitting.

 

Hope that's not "too much information" Rick!

 

BP