Sounds of Music C

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quizbowl
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Re: Sounds of Music C

Postby quizbowl » December 13th, 2010, 6:57 pm

1 x 2 pine, found at Home Depot (or any such home improvement store). The only problem is that it's soft enough for the "mallets" I'm using to make small dents in it.
How are you guys constructing mallets? I think we are using concrete as sort of a "jawbreaker" method of constant coats to form it into a ball - i bet that it would easily dent wood, but we are using copper piping.
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Re: Sounds of Music C

Postby doctor » December 14th, 2010, 8:28 am

1 x 2 pine, found at Home Depot (or any such home improvement store). The only problem is that it's soft enough for the "mallets" I'm using to make small dents in it.
instead of using a softwood like pine use hardwoods
the only problem is i'm having a hard time finding any with the correct dimensions...
also phillies413 are u sure a xylophone is low enough and can play from C2-D4? the bars will be awfully long...
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Re: Sounds of Music C

Postby AlphaTauri » December 14th, 2010, 12:31 pm

My test xylophone can play the octave from C4 to C5...If I double the length of the bars, I believe it will lower the pitch by two octaves, meaning I can hit a C2.

doctor: I have to file each bar, so I don't really want to use hardwoods, although I might try it, just to see if the increase in durability offsets the extra time I have to spend filing.
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Re: Sounds of Music C

Postby engineeringmaniac » December 14th, 2010, 8:04 pm

Wow so i just started looking into SO again (because i transfered high schools and i didnt think we were gonna have a team) and i just realized how far behind i am.

I was planning on building a mallet instrument and a recorder like instrument (i would love to make a reeded horn, as i play the clarinet and saxophone but i dont see how this would be possible), so i was just wondering if someone could give me some starting advice and could help me out on where to even begin.

Also is anyone having trouble reaching or covering the holes on their woodwinds when you get to the bottom of your range?
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Re: Sounds of Music C

Postby doctor » December 20th, 2010, 7:23 am

My test xylophone can play the octave from C4 to C5...If I double the length of the bars, I believe it will lower the pitch by two octaves, meaning I can hit a C2.

doctor: I have to file each bar, so I don't really want to use hardwoods, although I might try it, just to see if the increase in durability offsets the extra time I have to spend filing.
well real marimba bars are made of hardwoods
i havent really thought about how much harder it will be to file and stuff
your best bet would be to get as close as possible so u only need to use a little bit of sandpaper
also if u do use a softwood like pine and stuff if u cut an arch at the bottom wouldn't that increase the chance of the whole thing snapping?
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Re: Sounds of Music C

Postby zyzzyva980 » December 20th, 2010, 9:25 am

I should note here that we used a wood xylophone and scrapped it because we really couldn't find a very good way to attach the bars to the base without having them either snap or suffer a decrease in resonance. I'm no wood connoisseur, but I think we used the type of wood specified in the link I posted earlier, red oak, I think. We tried nailing the bars down but some of the bars split (hot glue worked surprisingly well in a pinch). We also tried velcro and of course duct tape but both decreased the resonance by a large amount. The moral of the story here is that attaching the bars to the base is very important and if you don't do it right, you'll have to suffer the consequences. That's for everyone using wood out there.
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Re: Sounds of Music C

Postby fossilgirl13 » December 20th, 2010, 12:23 pm

What exactly IS sounds of music? Some of my teammates are very lost and they need help (What things does one need, what is allowed, what is the goal?). HELP!!!!!!!!
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Re: Sounds of Music C

Postby doctor » December 20th, 2010, 12:33 pm

What exactly IS sounds of music? Some of my teammates are very lost and they need help (What things does one need, what is allowed, what is the goal?). HELP!!!!!!!!
the rules tell u what u need you should read them first
basically you need to build two instruments, one wind, one percussion and be able to play a scale and two songs with it
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Re: Sounds of Music C

Postby AlphaTauri » December 20th, 2010, 1:18 pm

I should note here that we used a wood xylophone and scrapped it because we really couldn't find a very good way to attach the bars to the base without having them either snap or suffer a decrease in resonance. I'm no wood connoisseur, but I think we used the type of wood specified in the link I posted earlier, red oak, I think. We tried nailing the bars down but some of the bars split (hot glue worked surprisingly well in a pinch). We also tried velcro and of course duct tape but both decreased the resonance by a large amount. The moral of the story here is that attaching the bars to the base is very important and if you don't do it right, you'll have to suffer the consequences. That's for everyone using wood out there.
The instructions that I found tell you to drill holes through each bar and then put nails/screws through the holes to attach it to the frame (but you have to use thinner nails/screws than the hole you drilled because the bars have to resonate), although I'm not sure how this is going to affect this pitch of the bars.
your best bet would be to get as close as possible so u only need to use a little bit of sandpaper
also if u do use a softwood like pine and stuff if u cut an arch at the bottom wouldn't that increase the chance of the whole thing snapping?
I used 2x1 pine...and even if you sand like halfway through, it doesn't snap when you strike it with a mallet (of course, that does depends on how hard you hit it). Also, sanding the bottom into an arch reportedly increases volume, which is why I do that instead of just cutting the bars to the correct pitch in the first place.
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Re: Sounds of Music C

Postby fleet130 » December 20th, 2010, 5:49 pm

we really couldn't find a very good way to attach the bars to the base without having them either snap or suffer a decrease in resonance
When you strike a note on a xylophone, the bar vibrates up and down in the middle and at each end.Image
There are two places, called nodes, where the bar doesn't move. Supports should be placed exactly at the nodes or they will dampen the vibration, making the bar sound dull or dead. Supports (and anything else) should contact the bar as little as possible. This means the area of the support in contact with the bar should be as narrow as possible. As you sand/trim a bar to tune it, the nodes may move. If they move too far, the holes will no longer be at the nodes and you may need to start over. One way to locate the nodes is to place supports approximately at the nodes, sprinkle salt/sand on the bar, and tap its center with a mallet. As the bar vibrates, the salt/sand will move to form a line at each node. Move the supports to these points and repeat the process until you are satisfied you have located the nodes.

Bars can be held in place by drilling a hole in the bar's centerline at each node and placing the bar over a pin in each support. Holes drilled at a node have little effect on the bar's pitch. The pins should be smaller in diameter than the holes so the bar doesn't contact them when its vibrating.
Image You can use a small rubber band or O-ring on the pin to minimize the area that contacts the bar. The height of the rubber band above the support may make a difference. The bar should fit loosely over the pins and rubber band/O-ring without actually touching them. When you strike the bar, it will automatically move to where it doesn't touch the pins.

As shown, the bars can fall off the pins while the instrument is being moved. You could use nails or screws with heads larger than the holes. To make it easy to remove/replace the bars, you could devise some sort of removable retainer (such as a hinged cover).

Here's a question: Does it matter where you remove material (in the middle or at the ends) when tuning a bar? This might allow you to keep the location of the nodes constant.

Here's a link that may help: http://www.tidewater.net/~xylojim/xylocons.html
Information expressed here is solely the opinion of the author. Any similarity to that of the management or any official instrument is purely coincidental! Doing Science Olympiad since 1987!


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