Planning to Build a Bass Marimba?
----- Original Message ----- From: Amos McCormick To: firstname.lastname@example.org Sent: Sunday, 19 May 2002 11:14 Subject: Building a Bass MarimbaHi,
I ran across your website while searching the internet for information on building a chromatic bass marimba. Back in the late '70s and early '80s I had done a lot of research and had collected a couple of sets of plans for building, but work, marriage, family, and all those "responsible adult" things got in the way and I never quite got around to it. Now that I am in a position to try again, I have no idea what happened to the plans and other information I had collected.
Obviously, you have built several instruments, and I would appreciate any guidance you might give me about where I might find plans and other information so I might start building. I have a lot of woodworking experience and the tools to do the job properly.
Thank you for your help.
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To be honest I don't know of any written texts or plans to follow that will really help you a great deal. I am no real expert in the practice of building marimbas - especially normally pitched ones. In my study days, I did develop a fascination for bass marimba notes and that lead me to study marimba building quite extensively and build some low pitched instruments.
There are certainly a few special considerations with bass instruments, and in some ways they are easier. The difficulties involved will to a certain degree depend on what range of notes you decide you want - and perhaps the range will depend on the difficulties you want to cope with. Designing an instrument can be separated into the 3 main areas of frame, resonators and bars. To a certain extent, bars and resonators go together, and resonators and frame go together. You certainly need to start with the bars though.
Low bars are in some ways easier to tune than middle to high bars. This is because the range of the fundamentals and harmonics are well within good hearing range and as you get lower the sustain increases as well. This means that the pitches involved are easier to both hear, and measure with reasonable accuracy using inexpensive equipment like a digital guitar-style tuner. (make sure you check out the specs of the tuner first though.) If you go too low though the fundamental will become difficult to both measure or hear. As the bars get higher, the sustain becomes less, making it harder to get a good measurement on the notes. The harmonics are also raised into the regions where they really require a stroboscope to measure them. Once you decide on note range you will need to come up with bar widths and lengths - it is probably best to find a commercial instrument with similar notes and take those measurements. You will then need to work out the lengths of the main struts that hold the bars, by taking into account the bar widths, and the gaps between bars including string holders, rubbers etc, and bits at the end of the struts.
With low pitch resonators - I personally think the best way to get them correct, is put them under the finished bar, and adjust them till they give the desired sound. Using PVC pipe makes this fairly easy. You can work out the approximate length of tube with 1/4 wavelength and end correction - then leave it a bit longer. You can leave a bit of variation by leaving the end cap or elbow join unglued and sliding it in and out a bit. You may have to cut a bit more and slide again once or twice but when it reaches the best sounding length - mark it with a texta, so you can glue it to the exact spot. All this would need to be done after getting a reasonable idea about what bends (if any) will be in the resonators - that way they can be cut to length with the bend in place.
Hope some of this is helpful.
answers by Jim MCCarthy - 21/06/01
For more help on marimba building you can email Jim.