A marimba project in Shymkent

Today I finished rough tuning the bars.  The last ones, from F4 down to C4 took a little longer than I expected because the F turned out a little problematic after I went too low and had to try to recover a few Hertz. The notes sound good close up, but there doesn't appear to be as much resonance in the bars as I had hoped or even expected.  Still. the sound is clear even if it isn't very long lasting.  If perhaps I could have got the hang of triple tuning it might have made a difference...but often the most pleasing sounding bars are not particularly accurately tuned...they just have better internal structure, I guess.   I am hoping the sound quality will improve once I have the resonators on.  I have to make them first though... By the way, this is not a full chromatic set - it is C4 through to C6 including F# accidentals but there are no B b or other 'black notes' so it can only play in the keys of C or G.

I designed this marimba on powerpoint because I find that a very easy programme to work with when it comes to overlaying shapes and stuff.  I am still working to the design for the soprano but as I close in on the end of the key making I am turning my concentration to the legs. Do I really want an instrument that folds where the legs are attached to the rails, or would it be better to make the legs a separate entity.  If the legs are separate the resonator rack can be dropped in first and the rails add on top and bolted down....umm... Well, I will still need to think about this.  In the meantime I have plumbing pipe to play with so I am not at the point of no return yet regarding the leg design....

So this picture compares what my two earliest trial bars look like after one of them was treated with liquid Kiwi brown shoe polish.  And if you are wondering why I keep playing my marimba bars with a screwdriver, it's because I have yet to find an alternative with the right hardness for those high notes. I made some great beaters from the cross bars of a couple of coat hangers to substitute for dowelling that I cannot get in Shymkent.  To the ends of these I glued some very hard rubber balls that I got from a pet shop; the kind of ball a Great Dane would struggle to chew to bits.  I drilled holes in them and glued the balls into place.  However, despite being hard rubber the balls are just a little too large and large makes them give just a tiny bit.  Therefore they don't quite have the punch I am seeking.  I may have to make more beaters from more coat hangers and, if I can get them, some rubber engine mounts, which I hope will be available from a...

Bringing you right up to date, these are all the notes I have completed.  The last few were done today and I hope to complete the second octave tomorrow.  Then I move on to resonators and legs for the beast.

At this point the F# is still off but the octave is coming into form....

So here is a run down the scale before tuning but with all the bars cut to length...

So, when I wish to tune a new bar I mark on one side of the bar the centre line, and the points that correspond to the distances that are 25%, 30%, 35% and 40% from the end of the bar. I open Audacity and do a test recording of the bar before removing any material.  This is usually way above the frequency I am looking to reach, but it is nice to have a record of where I started. Then using a round tipped 20mm router bit which gives a nice smooth curve to my first cut, and using the 30% line as my guide, I move the bar over the router (which is mounted upwards from under the workbench).  I say that I use the 30% line as a guide, but in actual fact the edge of the router curve just touches the 25% line on the higher tone bars. Once I have my limits defined, I remove the remaining 6mm from between these two cuts. Next I raise the router to about 11mm.  I now make two more cuts using with the same router bit, making sure that the edge of the router does not cross the ...

I watched a video about triple tuning a marimba bar using a router, by Lynxwatch. I applied these principles to tuning my keys, but in the early stages I was not particularly successful at triple tuning so decided I was happy with just tuning as close to the fundamental as I could get. Rather than using Baudline, which I found rather user unfriendly, I used Audacity to measure the audio spectrum of each bar as I tuned it.  My method involves opening a new stereo track and recording me playing the note near the computer's microphone.  I hold it by the nodal holes, and then tap it gently with a screwdriver handle to get a recording. I tap it several times in succession and then cut the recording back to isolate the best example in terms of amplitude and clarity. After this I select this region of the recording and analyse it using the plot spectrum tab.  This gives me data about the main peaks and lets me know whether any of the harmonics are also tuned.  I th...

My first router, made in China, fell apart and went spinning off near my feet...so that had to go.  This set my progress back a little but after pay day I was able to get a new Bosch router and this works a treat.

With my bench mounted mitre saw I now cut the 50cm karagatch lengths down to their new sizes. This meant that each bar was 5cm in width, 2.3 or 2.4cm in depth and ranged from 23cm to 39cm in length.  Here is the table I worked to; SOPRANO marimba C4 D4 E4 F4 F#4 G4 A4 Frequency 261.60 293.60 329.60 349.20 369.90 392.00 440.00 F4 (4 x Fundamental) 1046.40 1174.40 1318.40 1396.80 1479.60 1568.00 1760.00 F9.8 (9.8 x fundamental) 2563.68 2877.28 3230.08 3422.16 3625.02 3841.60 4312.00 Bar width cm 5.00 5.00 5.00 5.00 5.00 5.00 5.00 Bar thickness mm 22.00 22.00 22.00 22.00 22.00 22.00 22.00 Bar length cm 39.00 38.00 37.00 36.00 35.00 34.00 33.00 Nodes cm from ends 8.78 8.55 8.33 8.10 7.88 7.65 7.43 B4 ...

Here is the first key I tried to make.  At this stage I had used salt to find the nodes of the bar and had taken out wood from the underside using a small bladed saw.  However, I had cut too deeply into the wood and made the note too thin, such that it lost integrity and sounded too low to be of use on my two octave soprano. I tried a second time and got a little closer but impatience got the better of me and again I went in too deep.  I saved these early notes for experiments on staining with shoe polish (as it appears wood stain is not readily available in Shymkent either). You may notice under the table there is a mitre saw too.  I bought this so that I could cut the 50cm length bars to the correct lengths to match my stencils.  I would also have rails and legs to cut, so it seemed like a necessary thing to get.  I also bought a drill to drill holes for cords, and a router with which to tune the keys.  I mounted this under my workbench (a con...

Having found wood I bought some basic tools so that I could start modifying the sound each bar made by cutting out material from the underside.  However, I was unsure of where to cut.  How far should the arch extend, and how deep should it go? I still had no real answers when two things happened.  Firstly I received an email from Tom Bourne in the US with whom I had corresponded before.  His excellent and entertaining video on Crafting a Marimba was my primary inspiration and the best video out there in my opinion.  Tom has a whole workshop of power tools and makes marimbas for schools. He was kind enough to send me the dimensions he works to to make keys.  Although I was still a little unsure of how well they would translate to karagatch, I translated them from inches into metric measurements and on doing so recognised that there was a fairly clear pattern to their lengths. Around the same time I also came across a video from RockFreakinSolid that hel...

I have set out to build an African marimba.  I hope to build a set of marimbas so that I can create a marimba club at school. Unlike concert marimbas, African marimbas are played as a group with each instrument playing a different range of notes.  My intention is to build a soprano and a tenor marimba to start, and if the project goes well, maybe build a baritone too. Although I have worked in Africa and have had some experience of playing marimbas, I have never made one from scratch.   If you want to see the kind of instruments I played in Botswana, you can see some former pupils of mine with our marimbas on my wife's website, African Marimba Workshops . Setting out to make a marimba from scratch quickly made me realise how shrouded in mystery this art is.  However, I was determined to see the project through without reverting to buying plans off the internet. So, what problems was I likely to encounter? Well, the first was that I had no tools. The ...