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:

https://en.wikipedia.org/wiki/Piano_key_frequencie...

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.

Comments

[HéctorV7]

The preparation you made to cut in specific length the Tines (tuning the tines) became useless once you made the arrangment of the instrument with the length divided by half by the magnet, and the metal rods where the tines rest.

If you want to keep it in tune you should meassure the length from the resting rod, to the end of the tine (vibration length) you have well explained the vibration length on the pictures, just made the tines longer next time

Best Regards!

[MAGNET TRICKS]

I agree. My original idea was seen in the video, what I did with the green
Stahlwille wrench box. Then I used my cajon box as a sound box and attached a
metal piece on the cajon for the magnets and tines. I experimented with that
for a couple days and really got fed up with the sound and was ready to ditch the whole project as I stumbled upon into this idea by accident. When you say make the tines longer next time I guess you mean the tines could be equal in length?

[Oncer]

What was the metal wand you cut up for the tines? Is it stock strip or just something you had? Thanks!

[MAGNET TRICKS]

It was an old sewer pipe cleaner I found at a flee market :)

[Oncer]

Thanks. Never found a viable source of tines for mbiras.

[Trancified]

Add electromagnets underneath it, to each tine location, and control it with an Arduino or R-PI.

[MAGNET TRICKS]

yes, that's an amusing thought! thanks for the idea!! :)

[Oncer]

That sounds fun. Look up e-bow schematics. Generally a couple of coils (pickup and transducer/exciter) and an LM386 amp. Probably have to beef up the transducer as original designs are for strings not gurt lumps of metal.