![\"\"](\"http:\/\/leopardshark.com\/music\/wp-content\/uploads\/2012\/06\/formula.jpg\" "\\"formula\\"")
<\/a>Formulae from our spreadsheet<\/p><\/div>\n
Human hearing is imperfect in the highest and lowest ranges.\u00a0 High notes are heard by our brains as flat. It is intriguing. We have to make them sharp (based on the measured frequency) to hear them in tune.\u00a0 In the low ranges notes must be flattened.<\/p>\n
We have 6 bars that we have to re-make.\u00a0 We have cut them, and now need to drill the string holes and shape them.\u00a0 Most of them are in a range where the fundamental and the first harmonic are NOT a perfect two octaves apart.\u00a0 The first time we tried to tune that range our strategy failed.\u00a0 This time, we will shoot for an octave and a sixth as the harmonic.<\/p>\n
The video below shows a properly tuned bar.\u00a0 Three tones are heard: the second harmonic, the first harmonic, and the fundamental.\u00a0 The fundamental is so low, the little video camera has trouble picking it up.<\/p>\n
<\/a>A tuned marimba bar: demonstrating the harmonics (the movie takes a while to load…. be patient)<\/p><\/div>\n
Our next big milestone will be mounting the bars on some rails so Paul can play them. To do that, we must design and build 3 pieces: the rails, the rail hinges, and the posts.\u00a0 We will describe the rails in subsequent blog posts.\u00a0 Initial post construction is described below.<\/p>\n
Marimba bars are suspended by a cord so they can vibrate freely when struck.\u00a0 Between each bar a small post suspends the cord.\u00a0 On commercial marimbas the post is a small machine-stamped piece of aluminum.\u00a0 They often get bent.\u00a0 We have been exploring materials that might make better posts, and be relatively easy for us to fashion.\u00a0 A very strong nylon could do the trick. One interesting type of nylon that is sold by the commercial name Nylatron contains Molybdenum Disulfide.\u00a0 MoS2 is a grayish metal that is slippery.\u00a0 In many ways it is like graphite.\u00a0 When the particles are vanishingly small, it is a dry lubricant.\u00a0 Put into nylon, it makes a bit more slippery.\u00a0 Of course, we are exploring new territory with this material.\u00a0 It may not work.\u00a0 However, this entire project is an exploration, why stop now?<\/p>\n
A laser cutter would have been the perfect way to cut the Nylatron.\u00a0 But instead of vaporizing bits of the 1 foot x 1 foot sheet with blasts from an invisible laser, we choose to try our hand at sawing and cutting.<\/p>\n
<\/a>A (maybe not possible) plan for the spacers\/cord holders (posts)<\/p><\/div>\n
The nylon was tougher than expected, and a bit of lubricant on the hack saw blade spend our progress<\/p>\n
<\/a>A bit of kitchen Pam does the trick…<\/p><\/div>\n
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<\/a>Our first cut<\/p><\/div>\n
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<\/a>Cutting the Nylatron sheet<\/p><\/div>\n
Polyrhythms<\/strong><\/p>\n Paul must play music.\u00a0 While we work on the marimba, Paul has been working on snare drum set skills.\u00a0 He watches Drum Corp International shows on YouTube, plays the video in 1\/2 time, transcribes what he hears into music, and then practices the new rhythms.<\/p>\n He has been particularly interested in polyrhythms.\u00a0 One of Paul’s drum instructors encouraged Paul to put together a class.\u00a0 So last Thursday (June 28th), Paul taught a class.<\/p>\n The Polyrhythm seminar<\/p><\/div>\n Click for full handout from the class<\/p><\/div>\n <\/p>\n","protected":false},"excerpt":{"rendered":" Well, although we have made tremendous progress, we are currently in the doldrums of small tasks that seem to last longer than they should, and when completed, appear too insignificant to be considered accomplishments. Nevertheless, we press on. The tuning … Continue reading <\/a><\/a>