On Making a bamboo Xylophone #2 - (Discussions with Ran Liu)

-----Original Message-----
    From: "RAN  LIU"
    Sent: 19/11/03 5:01:23 AM
    To: jim@percussionclinic.com
    Subject: Bamboo Xylophones
    

Hi, my name is Ran Liu and I am a student of Thomas Jefferson High School Sci/Tech of Alexandria, Virginia. I am conducting a senior research project in which I am prototyping a xylophone using bamboo to construct the bars. I read your article about constructing a bamboo xylophone and found it extremely helpful; it gave me a solid start on my project.

Right now, I am at a point where I have constructed a test xylophone out of some bamboo from my friend's yard, but the tones I get from striking the bamboo bars are not particularly resonant. The tones are dull, almost like the tone produced by striking a wooden table. The bamboo I'm using is relatively large-- about 2 or 3 inches in diameter, and I was careful to cut the bars so that there are no joints on them. Right now I have been using wooden and metal materials as mallets. I am stumped right now as to how to get my bamboo xylophone to create more resonant, more musical tones. I would really appreciate any advice you could give me concerning bamboo type, cutting, mallet material, or anything else that may help me improve the tone of my xylophone. Thank you very much!

Sincerely,
Ran Liu

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Glad you found the article helpful - I'm not an expert particularly with bamboo, so I can't really help with info about different types etc. There are one or two things that may help though.

In general, harder timbers or materials tend to vibrate for longer than soft ones so it would likely be slightly beneficial to choose bamboo that is in the middle or toward the bottom of the cane that is harder and heavier. You may also find that the bars improve significantly as they dry out. Rosewood for marimba bars is usually kiln dried to about 7% moisture content then further air dried for 2 or 3 years before carving a bar - they still seem to improve for years after that.

You will also find that the bar suspension mechanism is crucial to achieving a good sound. 2 things will make a difference - 1 - finding exact nodal points and 2- having a suspension mechanism that allows the bar to vibrate freely - as little touching as possible. Some taught fishing line through a small hole is a system I have seen on quite a few bamboo instruments.

Different mallets would probably not make the sounds more resonant, but will certainly change the perceived character of the sound. Hard mallets like those with metal heads will tend to activate a high degree of the unwanted upper harmonics, while really soft ones, say wrapped in lots of wool will just produce a bass thump without targeting the antinode enough to activate the fundamental properly. Go for a small to medium head mallet - certainly no wider than the bar width, say 60% ish. What works well is a medium to hard core material like hardwood or machined nylon wrapped or covered in latex rubber, or even with a bit of Bicycle tyre tube stretched over it. This has a "two-tone" effect - soft when played soft, and harder when played harder.

Hope this has been some help.. And good luck.

Jim McCarthy

For more help on marimba building you can email Jim.

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