August, 2001
                           KORIMBA
                           ~~~~~~~
 
Korimba is a name that I coined for an instrument I came up with and 
have been experimenting with for a while now. Quite simply, this 
Korimba is (as the name implies) a cross between two African 
instruments -- the 21 stringed Kora and the Kalimba (also known as 
Thumb-piano). It plays (and is tuned) like a Kora*, but uses 21 metal 
Kalimba-type twangers (made from lawn-rake tines) in place of the 
Kora's 21 strings.


The biggest challenge was to develop twanger mounts that were 
orientated 90 degrees from that of the Kalimba to allow "side 
plucking", like the strings of a Kora, while still enabling the 
sound to be conducted efficiently to the sound-box.

A lot of experimenting has been done with this thing & I
anticipate a good deal more -- check back on this web-site for 
updates.

The twangers are plucked on their sides, near (but not at) the 
tips.

One nice thing about the field of musical instruments is that by
no means has every musical instrument already been invented!
You or I could invent an instrument a day for a long time to come.

                        MATERIALS USED
                        
Right and left sides - 3/16" plywood. I found some old panelling
                       that worked fine.
                       
Front and back - 1/8" plywood. From an old door in my case.

Twangers - 3/16" by 1/32" thick spring steel. I salvaged these from
           old lawn rakes. Other widths and thicknesses should
           work as well -- lengths would likely be different from
           what is shown here. If you used different type twanger
           stock, you'd have to experiment a bit to get right
           lengths. I have noticed a big difference in volume and
           tone by using different gauge & width twanger-stock.
           If you get a bad tone with one type, try another.
           
Twanger mounts - I used 1/4" long hardwood dowel pins bought at 
                 Ace hardware. These are Tietbond-glued into very 
                 snug holes. The middle mounting member for each 
                 of the 21 twangers is a 6 x 3/4" pan-head screw.
                 
"Resonator" - I used a 7" diameter by 1&7/8" high cookie tin.

                       CONSTRUCTION NOTES
                       
The body is glued together using titebond wood glue and 8 small 
blocks of wood in each corner for strengthening.

Try your best to mount the dowels so that the twangers will be as 
parallel as possible.

It's fairly critical that the metal screws be located properly so
that the twangers are sprung just the right amount to stay in 
place & not let the twangers buzz, but yet not be so "tight" as to 
make tuning difficult. I suggest experimenting with some scrap 
here before drilling holes in the real thing. If you ever find
that a twanger is loose, or buzzes, an easy fix is to remove the 
existing screw & replace it with one size larger diameter. 

Twangers can be cut to length simply by breaking them (carefully) 
with your fingers while held in a vise-grip. Use a grinding wheel 
to round off and dull the otherwise sharp twanger ends.

I found the box as described not to be quite as loud as hoped --
A rather goofy, but quite effective, soundbox was fashioned out of
an old 7" diameter, 1&7/8" tall cookie tin. I silicone glued this 
tin to the open top of the instrument (locate this tin as far back
on the instrument's open top end as possible, so not to interfere 
with twanging fingers). Then, carefully, using a stout utility 
knife, I cut a rectangular hole into the cookie tin's bottom, just 
a bit smaller than the large opening at the top of the instrument 
wooden part. Into the cookie tin's top I made a 2" diameter 
soundhole, positioned as far away from the player as possible (so 
as not to be positioned over & thus gazing at the ugly rectangular 
hole with it's maw of screw-tip "teeth"). This cookie tin 
resonator at least doubles the volume & the tone is quite nice. To 
lessen the natural tendency for the tin to vibrate loudly at 
certain musical pitches, I wedged what amounts to a sound-post 
from tin's floor to inside of the cover - located this as close to 
center of the tin as possible --- then secured this post as well 
as the entire cover with silicone glue. I may replace the tin with 
some sort of small wooden box at a later date, but for now I am 
happy with it as is. If I do replace it, it will be for aesthetic 
reasons --- altho as you can tell by my webpage, such 
considerations have bothered me little in the past.
                       
                            DIMENSIONS:
                            
- Both side panels measure the same - 6&7/8" heigth & 4&1/4" width.
- Front and back panels measure the same - 6&7/8"" high by 3"
  wide at the top, tapering to  1&5/8" wide at the bottom.
- Bottom rectangle is simply cut to fit on the four "wall" panels.  
- Top is left open - cookie tin resonator covers the top.
- See illustration for details of handle & twanger mount dimensions.

 TWANGER MOUNT LOCATIONS, TWANGER MEASUREMENTS & TWANGER PITCH
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
I am not at all fond of the metric system of measurement, but I
begrudgingly admit that it occasionally can be of some use. 
Such is the case here. So all measurements in the chart below, 
concerning dowel placement are indicated in millimeters.

LEFT SIDE: 
Refer to chart immediately below and to the accompanying 
illustration. Note that all 21 twanger mounts are made 
identically. Try your best to mount the dowels so that the 
twangers will be as parallel as possible to each other and to the 
Korimba's top & bottom). Note: this only shows the placement of 
one of the two dowels that make up an individual twanger mount The 
other dowel is mounted 1&1/2" due left of the first dowel, & the 
screw is mounted midway between the two but exactly 1/4" higher
(center-line to center-line). 

        | distance | distance |                
        | from the | from the |                    
left    | center   | center   |                     | musical
side    | of dowel | of dowel | overall | twanger   | pitch
dowel   | to       | to       | twanger | vibrating | of this
number  | "edge 1" | "edge 2" | length  | length    | twanger *
--------|----------|----------|---------|-----------|--------------
#A:     |    54    |   160    |   165   |   112     | C (2 octaves   
(topmost|          |          |         |           | below Mid. C)   
 mount) |          |          |         |           | 
        |          |          |         |           |               
#B:     |    54    |   147    |   140   |    90     | G (2nd G below
        |          |          |         |           |    middle C)
#C:     |    54    |   134    |   135   |    84     | A (2nd A below
        |          |          |         |           |    middle C)
#D:     |    54    |   121    |   130   |    81     | B (2nd B below      
        |          |          |         |           |    middle C)
#E:     |    48    |   108    |   119   |    72     | D (1st D below   
        |          |          |         |           |    middle C)
#F:     |    42    |    95    |   111   |    65     | F (1st F below
        |          |          |         |           |    middle C)
#G:     |    36    |    82    |   106   |    57     | A (1st A below
        |          |          |         |           |    middle C)
#H:     |   29.5   |    69    |   101   |    52     | C (middle C)
        |          |          |         |           |    
#I:     |    23    |    56    |    98   |   46.5    | E (1st E above
        |          |          |         |           |    middle C)
#J:     |    17    |    43    |    96   |    41     | G (1st G above
        |          |          |         |           |    middel C)
#K:     |    10    |    31    |    93   |    37     | B (1st B above
(bottom |          |          |         |           |    middle C)
mount)  |          |          |         |           | 
        |          |          |         |           |        


RIGHT SIDE: 
Refer to chart immediately below. Note that all 21 twanger mounts 
are made identicallly. Try your best to mount the dowels so that 
the twangers will be as parallel as possible to each other and to 
the Korimba's top & bottom). Note: this only shows the placement 
of one of the two dowels that make up an individual twanger mount 
The other dowel is mounted 1&1/2" due right of the first dowel, & 
the screw is mounted midway between the two but exactly 1/4" 
higher (center-line to center-line).

        | distance | distance |                
        | from the | from the |                    
right   | center   | center   |                     | musical
side    | of dowel | of dowel | overall | twanger   | pitch  
dowel   | to       | to       | twanger | vibrating | of this 
number  | "edge 3" | "edge 4" | length  | length    | twanger *
--------|----------|----------|---------|-----------|--------------
#L:     |    51    |   147    |   128   |    76     | C (1 octave 
(topmost|          |          |         |           | below Mid. C)
 mount) |          |          |         |           |
        |          |          |         |           |
#M:     |    45    |   134    |   121   |    66     | E (1st E below
        |          |          |         |           |    middle C)
#N:     |    39    |   121    |   118   |    60     | G (1st G below
        |          |          |         |           |    middle C)
#O:     |    34    |   108    |   113   |    53     | B (1st B below 
        |          |          |         |           |    middle C)
#P:     |    28    |    95    |   108   |    48     | D (1st D above
        |          |          |         |           |    middle C)
#Q:     |    22    |    82    |   105   |    44     | F (1st F above
        |          |          |         |           |    middle C)
#R:     |    16    |    69    |   100   |    40     | A (1st A above
        |          |          |         |           |    middle C)
#S:     |    10    |    56    |    92   |    35     | C (1 octave
        |          |          |         |           | above Mid. C)   
#T:     |    10    |    43    |    90   |    34     | D (2nd D above
        |          |          |         |           |    middle C)
#U:     |    10    |    31    |    89   |    32     | E (2nd E above   
(bottom |          |          |         |           |    middle C)
mount)  |          |          |         |           | 
        |          |          |         |           |        

*
The Korimba's overall pitch is one octave below that of a Kora.

The lowest few notes on my instrument could be a bit
louder/clearer. I'm experimenting with different twanger-stock &
will report any findings here. In the meantime, I find these few
low notes sound best if plucked at twanger's end using fleshy part
of your thumb. 

If your twangers do not lie as parallel as you would like, the
offending ones can be made parallel by careful, but forceful
bending into shape once the instrument is more or less tuned.

Dowel pins can be trimmed shorter once you see where the twangers
lie.

Looking at the accompanying illustration, it appears that the 
dowels are mounted at a slight angle --- this is not the case (it 
was just easier to draw it that way) --- the dowel holes should be 
drilled perpendicular to the surface of the sides.

Below are pics that were on the CD I used to make available:

 










These next six photos are not related to the 
Korimba article - but I threw them in here
anyways. They are of a Kalimba/Mbira I came
up with that plays (same notes etc) like
a kora. Fun little thing






Dennis Havlena - W8MI
northern Michigan
my webpage: http://dennishavlena.com

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