The Basic Layout

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The tenor marimba extends from G2 to C5, a total of nineteen keys including the F# keys that enable the marimba to play in the key of C and the key of G.  The longest key, G2 is 50cm long and subsequent higher pitch notes are successively 1cm longer, making the C5 key at the top of the instrument 30cm long, the same length as the C5 key on the soprano.  The keys are raised above the rails by a cord running through them and through a series of vine screws that are not fully screwed into the wood.  This removes the need for a second cord underlying the keys.  To ensure no keys bounce accidentally on the rails, the rails have a strip of draft excluded running along them and the cord is kept tight to keep the keys up off the rails. 

 

 

The resonator rack

 

The resonators are made from 7cm diameter plumbing tube that was cut using the circular saw.  The resonator tubes are plugged with electrical fittings - ceiling roses that fit the pipes perfectly that have a disc of foam core stuck to them to make the inner surface entirely closed and flat.  Each pipe is secured by thee bolts - two on one side and one between them on the other side.  The rack of resonator tubes must be fitted to the instrument from underneath, but when doing this on my own I actually find it easier to lay the instrument down to fit them and then raise it back up again afterwards!

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The tuning of the keys

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Tuning the lower register notes using Audacity was difficult.  I changed to tuning the keys by ear once I had a sequence to work with, and compared their frequencies with those generated by a basic tone generator downloaded from the internet and played by my old iPad.  I found this easier to do as I have experience tuning guitars, and this speeded up the tuning process.  However, I had no way to tune the harmonics using this technique and may well combine both techniques to more accurately tune the fundamental and harmonic frequencies of notes I may make in the future.

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In order to reach the lowest notes, (i.e. the G2, A2 and B2) the keys needed to be much longer than those on the soprano marimba.  Furthermore, they needed undercutting to such an extent that the wood became very thin at the centre.  This has made these keys potentially weak.  They also have less reverb than the higher notes and the sound they produce is generally lower in quality.  Really these notes need to be played by a larger instrument with wider keys that have more structural strength.  However, they are good enough for my current purposes.  If I find a supply of wider and more robust wood I may yet make a baritone marimba and remove these keys from the tenor after modifying the length of the frame.

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You can see the tuning process in the videos I have posted on the video pages of this website.

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