Ode to a Partially-Tuned Guitar

First video post in a looong time (the link in the last post doesn't count). Just got back to my dorm after a good Christmas break, and picked up my guitar... I was so excited to play again that I didn't even take the time to fully tune it before this happened:

also I have veiny hands.

Making That Which Makes Music

So this was the big Love family project for the past several months: building a vibraphone!

Ok, so it was mostly just my older brother Andrew and my dad. Actually it was mostly just my dad. But anyways, they found the instructions online (I actually don't know what site they found, otherwise I would link to it... maybe it was this one?). According to the 90-ish pages of instructions, it's about a 7-day project... but as my dad said, "just because God created the world in 7 days doesn't mean I can do the same." 

Those gold tubes are actually just PVC pipes with spray paint - the same stuff your plumbing probably uses

So yes, it was quite the undertaking, but it was definitely interesting to see how much cheap material was used. Other than the aluminum bars (which had to be specially cut), everything was made using materials found at nearby home hardware stores.

This next photo shows one of the crucial steps in the construction, and the only part I was really involved in: tuning the bars. When first cut into shape, each bar was actually several steps too high in pitch; to tune the keys, we actually had to carve out the metal underneath (with the help of a drill press, stone sander, file, etc) - first to within about half a semitone, then we'd get everything roughly in place, and then fine-tune them to be exactly on pitch (within 3% of a semitone). The pipes also had to be carefully tuned (they would resonate to amplify the sound of the bar), but it was crucial that the bars be as exact as possible.

Tuning metal bars is quite the challenge because not only are you grinding solid metal and you have to go reeeeeally slowly to make sure you don't go too far, you also have to worry about the overtones - you can't be guaranteed that the higher overtones will even be in tune with the main note (see here for a previous post on this topic). This is why some of the keys (mostly the bigger ones) have a couple different places that have been hollowed out - each one corresponding to the tuning of a different overtone. Even now, some of the lower keys don't sound quite right - the notes themselves are perfectly in tune, but their overtones aren't quite in tune with the main note, making them sound a little dull. But we were able to get rid of some of the more ugly-sounding problems, and now I'm pretty happy with how it all turned out.

This wooden box contains a motor (probably the least home-made part of the whole thing) - what sets the vibraphone apart from other similar instruments is that there's a motor can be turned on, causing fans in each of the pipes to rotate, causing the sound to fluctuate, causing a nice vibrato sound.

So there you have it. A home-made instrument. (mallets not included). Finished just in time for me to see it done before heading back to college the next day.

You may be interested in seeing a video of the thing in action... Here's a Facebook video in which Andrew introduces the instrument and improvises. Enjoy.