Pipeline: The Show

Last Saturday we played two shows at in Normal, IL. We had a lot of fun, and the two audiences were great!

During the Q&A session after one of the shows, we talked briefly about how we used math to build the instrument.  A man approached me afterwards and asked if I could explain in detail how the lengths of the pipes were calculated.  I told him I would write up an explanation and email it to him. This is that explanation:

Disclaimer: Do this at your own risk. We assume no responsibility if you injure yourself or someone else, or waste money or materials, in the process of building a PVC instrument.  If you aren’t good with math or tools, please find someone who is to help you.

In order to determine the length of pipe that will sound a certain note, you need to know the frequency (in Hz) for that particular note.  The instrument we play in Pipeline: Reloaded is basically an E major scale over 3 octaves, plus a few other notes.  To make it easy to build your own, here are the frequencies for our highest octave:

If you want other notes, you can find a complete chart at http://en.wikipedia.org/wiki/Piano_key_frequencies.

Side note: We chose to build our instrument in the key of E because several of our members play also play guitar, and if we ever wanted to have the guitar and pipeline instrument play together, playing in the key of E would make it easy on the guitarist.

Knowing the frequency of the note you want to hear, you need to calculate the length of the pipe to cut.  This is done with the following formula:

Length = (TubeDiameter / 2) + (SpeedOfSound / [Frequency * 2])

The speed of sound varies based on altitude, humidity, barometric pressure, etc… At sea level, it’s 13,397.244 inches per second.  If you’re in Illinois, it will be a little slower, but for the purposes of building our quirky instrument, we used the sea level value.

Finally, the tube diameter will depend on the size of PCV pipe you buy.  Our high octave is made from 2 inch diameter schedule 40 PVC pipe.  Here’s our final calculation for the length of that low E:

Length = (2 / 2) + (13,397.244 / [164.814 * 2]) = 41.644

Our low E needs to be 41.644 inches long.  That’s 3 feet 5 10/16 inches.

Armed with this knowledge, you can calculate the lengths for the other pipes, or for any other notes you want.

Please be careful when cutting your pipe to these lengths.  Playing a PVC pipe instrument is a lot of fun, but you need all your fingers to do it.  If you’re a young person, please get an adult to help you.  If you’re an adult, make sure everyone around is wearing safety glasses (if you’re doing this with a power tool like the mitre saw we used, plastic shards will fly EVERYWHERE) and keep everyone’s fingers well away from the blades of your tools.

Now that you’ve cut your pipes, you need something to play them with.  The simplest thing that we think sounds good is to find a pair of flip-flops lying around and hit the pipes with those.  Fun sounds!

Side note: We use a flexible plastic spatula with the flat part covered in two layers of adhesive foam rubber from a craft store, and then covered in duct tape.

That’s it! With a little bit of math and some readily available materials, you can build a simple PVC pipe instrument and make the same sounds that we do.

Have fun, and be safe!