A brief introduction to marimba tuning

Marimba tuning demystified

marimbatuning1

Hello fellow percussionist! Tuning a marimba seems to be a dark art to us percussionist. All of us know what a good bar sounds like but most of us have no idea what actually makes a bar sounds good, as such i will give a brief introduction to marimba tuning

The key to getting a good sounding marimba bar is in its overtone tuning. Between C2 to C4 you need to tune the fundamental, the first overtone and the 2nd overtone. Between C#4 to C6 you will need to tune the fundamental and first overtone. Finally, above C#6 you do not have to deal with overtone interaction.

Basically you want the fundamental and overtones to form a chord. So… what chord do you want? Well that is a tricky question and can only be answered by the wood you have! Different wood have differing overtone ranges. 

To keep it simple, you ideally want the fundamental and the 1st overtone to be 2 octaves apart, and the 2nd overtone to be 2 octaves plus a major 3rd.

What do you need?

– A blank marimba bar to tune
– A marimba mallet
– Strobe tuner
– Spectrum Analyzer (Optional but saves you lots of time)
– Belt sander

Spectrum Analyzer showing the 2 peaks.
Spectrum Analyzer showing the 2 peaks.

The above picture shows a audio spectrum analyzer showing 2 peaks when the bar is struck. the left side (bottom) one is the fundamental and the right side (top) peak is the 1st overtone. today we are tuning a Eb5 and as such we do not deal with the 2nd overtone placement.

SO.. how do we go about it? 

Take a look at the picture below first!

Sanding Regions.
Sanding Regions.

To keep things simple you want to lower the pitch of the bar by sanding. Region 1 is for fundamental, region 2 is for the first overtone, and region 3 is for the 2nd overtone.

You can use whatever method you can think of to shape the bar. I find the easiest would be a belt sander similar to the one below. 

Belt Sander
Belt Sander

As you sand, both the fundamental and overtones will go down at the same time, no matter where you sand.

– Region 1 will lower the fundamental the most, and 1st overtone a bit.
– Region 2 will lower 1st overtone a lot, and the fundamental and 2nd overtone a bit.
– Region 3 will lower the 2nd overtone a lot and fundamental and 2nd overtone by a bit.

If you are still following me so far… GOOD JOB!

As you can imagine, we are at the stage of the “Dark Art” by now. Basically its a game you play moving the Fundamental and overtones at the same time to hit your target pitches at the same time!

The name of the game is to do it SLOW, especially when you are reaching your target pitches. A small bit of sanding makes a huge difference! If your pitches become too low, the only way is to shorten the bar or bevel the ends of the bar to raise the pitch.

Want to learn more?

If there is anyone at all out there in sunny Singapore interested at all in marimba tuning feel free to contact us! I will gladly show you how its done or you can even have a go at it with some scrap!

meanwhile check out these links for more information on marimbas!
https://www.pas.org/Files/0708.52-57.pdf
http://www.lafavre.us/tuning-marimba.htm

Good luck and keep those sticks banging everyone!
Lin Chow