Bamboo marimba.. help!

[percoyssion]

any one know how to make a bamboo marimba?

[bamboojohn]

Well maybe not a conventional marimba, but Victor Cusack's book "Bamboo World" details how to build a boo bam.

[Mark Meckes]

Hi percoyssion,
Is there a specific style of marimba that you are interested in?
Not much on the internet about making bamboo marimbas ...
You may need to search for marimba, xylophone and vibraphone.

Here's some Bamboo Marimbas made by Angel Sampedro del Río (http://usuarios.arnet.com.ar/bambu/)

Bamboo Marimba - Pentatonic Scale
http://www.bamboocraft.net/gallery/data/527/thumbs/69marimbapent.jpg See photo (http://www.bamboocraft.net/gallery/showphoto.php?photo=437&cat=500&ppuser=69)

Bamboo Marimba - 3 and a half octaves
http://www.bamboocraft.net/gallery/data/527/thumbs/69marimba-009.JPG See photo (http://www.bamboocraft.net/gallery/showphoto.php?photo=436&cat=500&ppuser=69) http://www.bamboocraft.net/gallery/data/527/thumbs/69marimba-007.JPG See photo (http://www.bamboocraft.net/gallery/showphoto.php?photo=435&cat=500&ppuser=69)

-------------------
From a web search, see ...

Article - The Art and Craft of Building Marimbas (http://www.dandemutande.org/Magazine/Golovnin1.asp) by Stephen Golovnin
Though this article isn't about using bamboo, but provides an interesting perspective on the selection of marimba making materials.

Another interesting article ... Making the bars (http://www.outback.chi.il.us/~bonnysu/craftymusicteachers/bassmarimba/bars.html)

Publication - Make Your Own Marimbas (http://www.vosa.org/paul/sales_folder/marimba_make.htm) by Jon Madin

Great Website ... Experimental Musical Instruments (http://www.windworld.com/index.htm)

See - FREE-BAR CALCULATOR (http://www.windworld.com/tools/freebar/index.html) Software designed by Peter van Gorder / User notes by Bart Hopkin
From the site ...
"Free bars are musical bars or tubes mounted in such a way that with neither end is fixed in place and the fundamental mode of vibration is uninhibited. This includes things like marimba and xylophone bars, vibraphone bars, wind chimes and other tubular chimes, and tubulons (metal-tube marimbas). This software will tell you how long to make the bars on free-bar instruments in order to get the pitches or scale you want."

Have fun!

Mark

[sound world]

If you chop up some split guadua or similar,into various lengths 6-12" long by c.3" wide,you can hear their pitches readily enough-dropping them,for example!
Thereafter tuning is done usually by LOWERING the pitch by removing DENSITY,usually near the centre under the bar.This is more difficult with bamboo as opposed to wood,but still possible,and the pitch can change a lot! Obviously you can raise the pitch by reducing the LENGTH at the ends.
The bars should be mounted/held at each end at the point of least vibration,that is,22.5% of the overall length,or between 1/4 and 1/5 of the overall length.
And then you can make resonators,which is fun!

[Angel]

Theoretically, frequency of a regular bar is governed by its length, its thickness and its material density-in fact, internal speed of sound. Geometric shape also determine the frequency (by the Young's modulus). Doesn't matter if the bar is more or less wide.
Loudness is primarily determined by the damping coeficient- effect of frictional losses into material (called tau, if I remember well) and secondary, by the surface of the bar.
Formulas if you like, ask me, but they aren't very useful with bamboo.

Notice that variying the width of the bamboo bar also vary its resonant frequency. It is due to the geometry of bamboo -you are dealing with transversally curved instead of flat bars. If other magnitudes are the same, the more curved the higher the pitch.
When you reduce the width of a curved bar, you are actually modifiying its thickness at the same time. The thicker the bar the higher the pitch, so...reducing width, lower the pitch.

As it is a general rule, and a rigid bar under a force tends to vibrate in some and no other manners, reducing the thickness in antinodal zones lower the freq much more-for the fundamental mode, at the center of the bar.

I normally use bars no so wide as sound world suggest, achieving low notes with relativelly short bars. But these wide bars would act better without the use of aerophone-resonators