3

I am new to StackExchange, and I have a question about a school project I'm working on involving constructing an instrument. I am building a xylophone-glockenspiel-mash kind of thing, but I wanted to save some money on materials and I need to know: If I have the right material, and I know the current length and the current pitch in Hz when struck, can I calculate the length it needs to be to reach a specific note (in this case, F4)? The current length is 3ft or 91.4cm, and currently it hits 218.2Hz when struck. I have found nothing in my searches on the internet so far, although this may be because I don't know the proper terminology to search for. Thank you for reading, and thanks in advance for helping.

  • 1
    It will depend entirely on the type of material used for the bars, a certain metal alloy or type of wood. And if it is wood, it will vary with the density of the grain of the wood, its age, or its moisture content. I don't think you can easily generalize. You'll certainly end up having to mill or cut blocks and carefully cut them to tune them by hand and by ear. – user1044 Mar 31 '14 at 7:54
  • There are other criteria you may want to take into account, especially harmonicity. I’ll try to find my old musical acoustics notes, but I have little to no hope. – Édouard Mar 31 '14 at 17:00
  • Usually the length isn't even that important. In many instruments the lengths are chosen in an aesthetically pleasing way, but you can do a lot by tuning them, see e.g. here: youtube.com/watch?v=5PesHXkN2M8 – flawr Jun 10 '17 at 9:39
4

This question is more suited to physics stackexchange but anyway..

This shows you to calculate frequency of vibrating bars, rods and tubes:

http://fiziks.net/physicsmusic/Experiment%2010.htm

This is a paper on building a copper tube Xylophone:

http://users.df.uba.ar/sgil/physics_paper_doc/papers_phys/lapp.pdf

If you have any further questions check out physics SE

  • fiziks.net appears to be 404 – buildsucceeded Jan 18 '18 at 23:54
1

Eq. 4.39 of H. Olsen, Music Physics and Engineering 1967 gives the equation for the fundamental frequency of a free bar. For this problem, where you have the same material and the same cross-sectional shape, the frequency is proportional to 1/(length squared)

0

I think that rote numbers will not work. Wood is not a material of homogenous resilience, and xylophone bars are hollowed out for best resonance (and as part of tuning). So you need to figure in some waste material for experiments.

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.