Tuning Marimbas - Finding the Nodes
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- Опубліковано 18 тра 2009
- How to FInd the Nodes on a marimba bar using the salt test. Some hinst on the tuning process for marimbas and other tuned percussion instruments. www.makeamarimba.com
- Навчання та стиль
Quite easy to follow. Great
I'm watching this on June the 19th, 2019. Exactly ten years and one month after it was uploaded. I'm surprised about the scarcity of comments compared to the number of views. I find this very useful and informative.
I've been interested in learning the basics about marimbas hoping to make me one. More as a toy than one actually tuned to perfect pitch. Thinking of it more as of those of primitive and rudimentary manufacture like for tribal use.
Thanks for sharing. Greetings from Tijuana, México.
Thanks Miguel. Good luck with your building. It's a fun process!
Thank you. Greetings from Tijuana, México.
If we have made the arch on the upper side
It has been right,so we must Check the nodes before carving,thank you for the Information,that saved lifes😁😁😁👍🏻👍🏻👍🏻
Nice. Good to know!
thanks!!!!
Just wondering... Is this method the same for the build your own vibraphone bars? also, how long does the average project take?
boa noite. Espero que me ajude. Amigo, você coloca a tecla de madeira sobre o elástico para descobrir o ponto nodal, certo? Mas as teclas da marimba ou xilofone não são de tamanhos diferentes? Então se eu pegar outra tecla, irei conseguir saber seu ponto nodal? Ou a partir da primeira você vai marcando com lápis as outras? Feliz ano novo
all the bars are different sizes - so you do this for each bar to find the nodal point. Then when it comes time to build your instrument you find the "average nodal line" that best fits the nodes on the whole row of bars. This is where you build the struts that hold the bars so that they are all held as closely as possible to their nodes.
Soy de Guatemala la marimba es parecida al xilófono pero es de madera con barias teclas
It would seem to me that if the finding of the nodal points was done before the sanding process one could flip the bar over and choose which side is up to gain more freedom of placement of the bar in question.
+kiaweking Well yes - that is exactly what this is telling you - see the comments below where this has been covered before. It is a good idea to do some initial sanding on both blank faces of the bar - just to smooth them - before cutting the arch though - this will make your first salt testing stage easier as the salt migrates more easily across the bar face.
+percussionclinic Bought the plans (two octave)from you over a year ago. Just now getting time to execute the project. Intitially experimenting with eucalyptus globulus and also prosopis pallida.
The instruments will be donated to our local elementary school for music classes. Thank you Jim for your assistance and for making these plans available.
Aloha from Hawaii,
THomas
+kiaweking Great stuff! And you are very welcome! Please feel free to get in touch if you have any issues or questions as you go... I'm here to help!
Wooden bars over time slipping out of tune:
Both factors combined--wood drying out and abuse--which direction in pitch do bars tend to go? What percentage of bars go flat? What percentage of bars go sharp? Consistent and predictable?
Thanks : )
In my experience bars almost always go sharp from original tuning over time - which is ok because it's quite easy to tweak them back down correctly after some time. It's quite common to do this for any new instrument after its first few years. It is POSSIBLE for it to go the other way - which as long as it's not too much, can still be corrected, but it's not as easy or good. A bar might for example go flatter over time if the timber was initially over-dried and/or made in a hotter and dryer climate, then moved to a very humid climate where it could actually gain moisture over time. Mostly though, bars tend to LOSE moisture over time which makes them sharper. The issue of tuning drift has become more over the last couple of decades as it becomes more and more difficult to get good wood. Early instruments were often made from great old growth wood that had been allowed to naturally dry and stabilize over years - these days it's more common to have greener and younger wood and need it in a hurry which means kiln drying. Nothing wrong with kilns but it is not a perfect process and wood will still either gain or lose SOME moisture often after the process till it finds EMC - "Equilibrium moisture content". So we are seeing more instruments built from wood that has been kiln dried, then often bars made without enough time for the wood to reach EMC BEFORE the tuning - so they drift more.
I am building a marimba and have rough sanded all the bars and are trying to find nodes but the salt doesn’t seem to go into lines on some of the bars especially the smaller bars is there another way to find nodes or could I be doing something wrong
I would not worry too much Lincoln - the smallest bars can often be tough to get a result on and in those cases just choose a side that seems best. The first round of salt testing will be tougher as the bars are higher in pitch and the vibrations even faster. You may well find that those same bars can get a decent result once you have rough tuned them to a semitone above target pitch. That is around the point where you will salt test them the second time to actually find the node POSITIONs - the first time you only need a rough idea of the node direction - position is not relevant as it will move during tuning anyway.
Also, might you know of an ultra-advanced method for node-finding, like a fancy camera that detects/shows vibration-imagining? Might you know how the big boys do it? I can’t imagine the Marimba One and Yamaha guys doing the salt trick for all their thousands of bars. 🙂
That sort of thing can work for sure - or strobe photography - but the "big boys" actually don't do it at all! Initial designs are created the old fashioned way most likely using exactly these types of methods - salt that is - but once the dimensions are created they no longer test bars - they just make them to the pre-determined dimensions to fit FRAMES that are also of pre-determined dimensions. By carefully controlling the materials to make them as uniform as possible you end up with consistent enough results. One of the advantages of a custom instrument is that you get the EXACT best frame dimensions for your exact set of bars - and you can make those bars in such a way that natural node angles better match the drilled holes you end up with - you don't get that with most commercial instruments.
Well assuming you actually have TWO good faces on the bars rather than just one, you don't need to leave any bars longer - you can simply use the angle to determine which face of the bar you will cu the arch from. BUT yes you are correct that tuning will move the modes - outwards. You salt test the bars twice - first time is ONLY to determine the angles therefore the tuning side of the bar. The 2nd test is done after the rough tuning stage and THAT one is done for positional information.
i call firstest!!
Hmm, putting the rubberbands roughly beneath the nodal points may yield a false reading, eh? Please explain why this is. Seems unintuitive.
Considering the spectrum of band placement, if bands beneath nodes is no good, then with this logic I would imagine putting the bands all the way to the very ends of the bar would be the best..??
If bands are beneath nodes, is this a problem because of something simple, like “the bar will vibrate TOO much causing the salt to scatter,” or is it to do with the scientific vibrations/overtones? 🤔
Thanks Jim 🙂
Generally it will not create a BADLY false reading but the salt will congregate at the point of zero vibration so if the bar is being "held" by the suspension it tends to MAKE that a node. It's best to have the bar as free as possible if you want a really precise reading, but that's not common. No - you don't wat to go to the bar ends - or actually too far away from the real nodes - because those areas are vibrating up and down they will push against the more stationary rubber and "bounce" the bar which then scatters the salt right off - hope that clears it up!
Sorry, the background noise is horrible
Dude, cmon, it adds that classic old UA-cam vibe, the vids from 2009