Introduction: Magimba - Musical Instrument - Magnetic Kalimba
Kalimba like musical instrument that utilizes magnetism in its sound generation.
Step 1: Tuning the Tines
The whole project starts by cutting the metal wand. For this step you need to install a tone recognizer app in your phone if you don't have a proper tuner or have an absolute pitch. The metal wand I used had a width of 5 mm and thickness of 0,7 mm.
Lengths of the tines that produced the major C scale
C = 101 mm, D = 94 mm, E = 88 mm, F = 86 mm, G = 81 mm, A = 77 mm, B = 73 mm, C = 71 mm
There is no reason why you should stick in to the C major scale, make it in what ever tuning you want.
Here are the frequencies in normal 440 Hz tuning:
The best way to tackle the tuning is just to jump right into it. It is pretty straightforward task - shorter lenght equals higher pitch. If you go little bit over the target frequency you can correct it by sanding the tine thinner, because thinner tine equals lower pitch. Once you have got one wanted frequence in other words determined the length needed for it - determining the rest of the remaining tine lengths becomes easier.
Remember to sand all sharp edges from the spots that are played in the tines.
Step 2: The Sound Box
The sound box I used was cigar box found at flee market.
Measurements: 24 cm x 18 cm x 4 cm
I drilled a 2" hole into the box
I attached a metal plate ( 17 cm x 12 cm x 1 mm ) to the wooden box with magnets
Step 3: Bridges and Magnets
The bridges are couple of Ø3 mm grill sticks positioned, not paraller but on a slight angle, I never figured out exactly what would be the perfect angle or a ratio of bridge gap to total length of tine, but approx 1:5 ratio seemed to get a harmonious sound out. The bridges are attached to the metal plates with powerful magnets. This enables later adjustments on the angle of the bridges.
Underneath each tine, in the gap between the bridges there is a Ø8 mm x 2 mm disc magnet.
The sound generation is a two stage process:
1. Tine is pushed down. This generates a lower tone because the section that is vibrating is longer.
2. Tine is released, Here the tone is higher because the vibrating section is shorter.
Free movement of the tines enable fine tuning.
To get the wanted scale. The tines should be placed on the bridges symmetrically so that each end of a tine is equal in length from the bridge, but you can also explore with different tunings.