Building a PVC Instrument

Brought to you by NateTrue.com

Phase I: Planning

Deciding which notes to include

First of all let me explain that cutting and tuning tubes is a very laborious process. Making fewer tubes means that your project will take less time to finish. The common piano scale has twelve notes per octave: C, D, E, F, G, A, B, and the five sharps and flats. That’s a lot of notes…

But don’t give up hope; if you’re designing the instrument to copy the Blue Man Group, you need only build seven notes, in this order, each octave: F#, G#, A, B, C#, D#, and E. So the simplest tube instrument you can make will have only seven notes, a breeze to build. If you’d like to span more octaves, I’d suggest you start at your lowest F# and end at a higher E.

The tube instrument my friend Jesse and I constructed had fifteen tubes, starting at a low E and traversing two octaves up to a high E.

Doing the math

Yes, I can hear the silent groan in your head, but believe me; if you crunch the numbers for your tubes you’ll save many hours of work later on.

Middle A has a frequency of 440 Hz. For every half-step up (which is one key on a piano, including black keys), the frequency is multiplied by the twelfth root of 2 (approximately 1.059) to get the next note. As you can probably guess, in order to go down a half-step, one simply divides the frequency by the twelfth root of 2 (still approximately 1.059). For octaves, one simply doubles or halves the frequency for going up or down an octave, respectively.

So the seven notes I’ve advised that you use have these frequencies:

Note name	Frequency
F#	92.499
G#	103.826
A	109.547
B	123.471
C#	138.591
D#	155.563
E	164.814

“Now,” you may be saying, “that’s all well and good, but how do I get my tube lengths from it?” I’m glad you asked (or rather, that I observed you asking…). The formula is quite simple (as are all physics formulas):

Of course, everybody knows the speed of sound, right? RIGHT? (Insert blank stare here) That’s okay. Even if you found it somewhere on some website, chances are it would be off a bit, since the speed of sound varies rather significantly from place to place. Therefore, what I suggest is that you cut a piece of tube for testing (a “test tube,” if you will) to about 35 inches. Grab a tuning fork, piano, or well-tuned guitar, and cut the tube down until it’s an exact A. Then use this formula to calculate your speed of sound: (Note that Frequency should be 220)

With any luck you’ll have gotten somewhere around 13300 (assuming you used inches in your measurements), or 33782 (if you used centimeters) — and don’t even ask me about sticks, rods, or spans. Anyway, if you didn’t get something like that, then you did it wrong.

So now you have the speed of sound. What’s next? Wouldn’t you like to know…

I guess you probably would.

I definitely would.

Okay then.

What you need to do now is calculate your table of lengths using the first formula I gave you.

Easy, right?

If you don’t want to do the math, download my Excel spreadsheet and just change the Speed of Sound in it.

Congratulations! You’ve survived the math section. (Or you may have skipped it; I have no way of knowing, so if you did, good for you; I don’t care.)

Deciding on a layout

The Blue Man Group’s PVC instruments are made of two tiers, 15 tubes per tier. The tubes are vertically placed, and they loop around quite a bit. You may decide to arrange them differently, perhaps laying the tubes horizontally, or only a single tier. You may also wish to curve the instrument around the player so that it’s easier to reach notes. It’s entirely up to you. Right now you should have some image in your mind of what the instrument should look like. Remember to take into account the lengths of the pipes calculated in the previous section; you can use pipe elbows to bend them around, but the entire tube must be accounted for.

Microphones?

Given the semi-quiet nature of the tube instruments, you may wish to install microphones in your tube instrument. The best way (I say this because Blue Man Group did it) would be to curve all your tubes in a way that points them at a common point, where a microphone will be placed. Another method could be to get little tiny microphones and put one in each tube. The microphones are entirely optional, though. I just wanted you to consider it now, because if you don’t plan for it it’ll be much harder later on.

On to Phase II: The tubes

Back to the Index

Questions? E-mail pvcmaster@natetrue.com