The Play Hear installation which appeared in San Francisco’s Market Street Prototyping Festival is an interactive sound structure which includes many playable instruments. The instruments are all tuned to agree with one another, making the structure in its entirety a jam session waiting to happen. In this Instructable I’ll describe how to make one of the structure’s instruments, namely, the stamping tubes.
Historically, instruments fitting the description of stamping tubes have appeared in music cultures widely dispersed around the globe. Typically a stamping tube is a bamboo tube between several inches and several feet long, with one end stopped by a natural node. The player thrusts the stopped end downward against pavement or another hard surface to excite a clear air-resonance tone in the tube. Stamping Tubes are sometimes played by groups of marching musicians, each with one large tube, together creating a polyphony of pitch and rhythm. Smaller stamping tubes may be used too, as a single player holds one or more in each hand to make music as light and playful as a running brook.
Step 1: Materials
Nominal 3" (80mm) PVC tubing, about 28 feet (9 meters). This material is widely available and inexpensive in hardware stores, sold as drain pipe. It’s very light in weight yet strong enough to sound clearly, making it eminently suitable for our purposes.
Six PVC end-caps to fit the tubes. Various sorts may be found in hardware stores. Whatever you use must be solid; the thinner plastic stoppers called “knock-out plugs” are too light.
Optional: inner-tube rubber – enough to cover the ends of the six tube stoppers.
Hacksaw or carpentry saw.
Optional: Hand files or sand paper.
Step 2: Design
The six stamping tubes in Play Hear are set in a special mounting that allows a single player to control six differently pitched tubes. This Instructable details how to make something closer to the traditional stamping tube set without the mounting, suitable for the sort of hand-held multi-player marching-band playing described above. At the end of the Instructable I’ll add a few notes on the how to make the single-player mounting mentioned above, but without full details.
The stamping tube set described here consists of six fairly large tubes closed at one end. It’s made with 3" [80mm] PVC because that’s the largest diameter that most people can hold comfortably in one hand. (If you are working with small children, consider using 2" [50mm] tubing and, to maintain the correct tuning, increase all tubing lengths by 5/16" [.8mm].) The suggested lengths will give you a very musical and easy-to-use five note major pentatonic scale in a standard tuning which allows you to play along with other instruments in this scale. (The six tubes all together include the five scale notes plus an octave duplication at the top.)
Step 3: Fabrication
Cut the six tubes to the indicated lengths.
G 67 7/8" 172.4cm
A 60 3/8" 153.3cm
C 50 9/16" 128.5cm
D 44 15/16" 114.2cm
E 40" 101.4cm
G 33 3/8" 84.8cm
Place the end-caps on the tubes. You can use PVC cement or other suitable adhesive to fix them on permanently, but if they fit snugly it may be unnecessary to glue them.
Optional: cut circles of inner-tube rubber to cover the bottom surface of the end-caps, and glue them in place. When you stamp the tube down onto a hard surface, the rubber will muffle the contact sound and let the tube-tone emerge loud and clear.
Note: Different end-caps have different shapes. The lengths given here allow for the likelihood that space within the end-cap will add a bit to the tube’s effective length, but it’s possible that your end-cap will enclose more air than other types, making the resulting pitch a tiny bit too low. Even if this is the case, the difference may be too small to be concerned about. But if you find when you’re done that all your tubes are pitched a bit too low, you can correct the problem by shortening your tubes a small amount.
Additional Notes on the Mounting System Used in Play Hear:
Having made the tubes, you have the further option of foregoing the group playing and mounting the tubes in a way that allows a single player to control many tubes. Here’s a description of how we did this in the Play Hear installation. I won’t provide full details here, but I’ll provide enough information to give you a good start on working out your own design.
The key is to suspend the tubes on some sort of stretchy or springy mounting such that the tube bottoms are positioned a couple of inches above the ground when at rest. To sound them, the tubes can be pressed down to strike the ground, allowing them to spring back up to rest position after. For stretchy mountings in Play Hear we used latex tubing, which functions like a giant rubber band. Each tube has two of these stretch-straps attached, one on each side, at a suitable height to allow the tube to hang nicely. The mounting must be attached in a way that does not create any air leaks in the tube (which would destroy the tone); thus, if you’re going to place any screws or bolts in the tubes, you must be sure that they fit tight and are screwed down snugly. To get around this in Play Hear, we depended on large hose clamps. These are metal straps with screws for tightening so that the straps can be tightened securely and immovably around a tube, with no piercing of the tube required. They’re widely available in a range of sizes at hardware stores. It was easy to clamp the latex suspension cords to the sounding tubes using the hose clamps.
You’ll need some sort of mounting framework to suspend the tubes from. In Play Hear we used one of the wall panels that formed the main structure of the larger installation, but you might come up with some very different sort of framework for the purpose. There has to be a way to tie the upper ends of the stretchy cords to the mounting so that the tubes themselves hang freely without touching any solid parts.
You may find that it’s OK to let the tubes hang from their suspension cords without anything around them to constrain their movement. For Play Hear, since we know the public would be playing the instrument and all kinds of crazy things might happen, we felt a need to restrict the tubes to a narrowly defined path of motion. The tubes pass through brackets attached to the wall panel, with a higher and a lower bracket on each tube. The brackets are just large enough to let the tubes move up and down within them with minimum contact, but they prevent any swaying form side to side or front to back. These brackets are made of steel rod bent to a U-shape for attachment to the wall, covered with latex tubing for padding and noise-reduction.
A “Press Down” handle is added to each tube at a suitable height for easy playing.
Step 4: Installation
For our purposes we threw the stamp tubes in the back of the truck and hung them on our structure out on Market Street. You might want to mount them to a wall or a cubicle divider. They are light but if you have them hung together, the move can be awkward, so ask a friend for help.
Step 5: Interaction
How to Play:
Distribute the stamping tubes among six players (or among three playing two each). Play them by stamping them, closed end down, on a solid surface. Wooden floors do not give good results; concrete, cinder blocks, large stones and very hard dirt floors do. You can add to the effect by using a stick to strike the side of the tube as well, adding a contrasting percussion sound to the mix.
I love the idea of the stamping tube in this traditional hand-held form because it’s so simple and it works so well as a non-military marching instrument. It’s particularly well suited to hocketing. Hocketing is the term for a highly cooperative approach to group music-making in which no one player alone attempts to play a melody. Instead, since each player controls only one or two notes, the melody takes shape as the notes of the melody pass from player to player in turn. In this interplay, highly rhythmic styles of interplay may also naturally arise.
Watching people on Market Street enjoy themselves was delightful. All day long spontaneous jam sessions broke out. Passers by would stop to explore the sounds and in turn listen to the street itself and connect more deeply with our city. Groups of unlikely allies gathered. People of all genders, ages, physical and financial ability played together in the street. Children especially seemed to love slowing down their parents and sitters. Several people came back after work or returned a second day. We also had a table with a teaching artist making instruments with the public. The Tenderloin came out in force and the community adopted Play Hear.