The Pyrophone

When Matt Nolan and I were separately asked by Stella Artois to brainstorm ideas for the Stella Artois Chalice Symphony, we both had a pyrophone on our list. Partly because it fits the requirements and partly because we were each really excited to build one!

The Pyrophone uses the shape of the inside of the chalice much like a singer’s mouth. We’ve added it to the ends of long glass tubes to change the timbre of vibrating column of air. And a flame provides the vibration, much like the reed of an organ pipe.

Photo by Jenny Long

Set design by Andrea Lauer. Photo by Jenny Long

The Inspiration

The first Pyrophone was invented by Georges Frédéric Eugène Kastner sometime in the late 1800′s. Our few clues about how to build one come from this beautiful old photo.

That's one flammable looking room.

That’s one flammable looking room.

Sound from Fire

We knew that the glass tubes would behave a little like organ pipe tubes. The pitch of the sound changes with the length of the tube. And we adjust the diameter to accommodate the shape of the sound waves in the contained column of air. The flame must act like the reed or mouth of an organ pipe. But why does the flame set the air vibrating? How do we make sound from fire?

The Fire

Karl designed several experimental torches with electronic controls. We got a lot of fire in our first glass tubes. But the only sound was us shouting with excitement and fear.

What could possibly go wrong?

What could possibly go wrong?

One of Karl’s many gas actuator prototypes:

After many experimental prototypes, we finally started producing sound using high pressure flammable gasses and torches with Venturi tubes.

The Glass

How do we make specific pitches?

Once we could make sounds, Matt put his skills to work with giant tubes of laboratory glass, specialized blades, and digital and analog tuning equipment.

Tubal Ligation

Tubal Ligation

The process was both scientific and surgical. Matt, his apron caked with wet glass dust, measured lengths, widths, gas types and pressures, pitches, and overtones. He wrote his findings on the glass, covering the tubes with lines, numbers and symbols.

Cutting the sturdy Pyrex tubes

Cutting the sturdy Pyrex tubes

Flame test with Matt Nolan.  Photo by Green Card Pictures.

Flame test with Matt Nolan. Photo by Green Card Pictures.

Gettin' vertical with Matt Nolan.  Photo by Green Card Pictures.

Gettin’ vertical with Matt Nolan. Photo by Green Card Pictures.

The Sculpture

Kastner’s pyrophones were gorgeous instruments. I wanted to do their memory justice, but use a new and original form. Ours would have the general aspect of a person. A 14 foot tall person! Its palette of materials would be light maple, dark steel like an approaching storm, flame, and glass tubes reflecting and counter-reflecting everything.

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The original star base was inspired by the eight-pointed star on the Stella Artois chalice. And the instrument’s eightfold radial symmetry echoes the star.

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The steel tuning collars can telescope up and down at the tops of the tubes to fine tune the pitch.

Photo 2013-07-12 04.59.27 PM

The original wooden base worked well visually. But we needed a much bigger one to contain all of the machinery and gas tanks. It still echos the star.

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And here is it all together.

I am forever grateful to these kind and ingenious people for all of their assistance:

Karl Biewald – Mechanical Engineering and Fabrication. Electronics.

Matt Nolan – Pipe Tuning, Torch R&D

Marina Litvinskaya – Fabrication

Devin Budney – Fabrication

The Violina

The Violina is part of the Stella Artois Chalice Symphony. It plays music by bowing tuned Stella Artois chalices with a circular bow of Mongolian horse hair. The player can play any combination of 18 chalices and quickly adjust the pressure and bow speed to create many voices and nuances.

The finished Violina

Set by Andrea Lauer, Photo by Jenny Long

Inspiration

The Violina is named after the Hupfield Phonoliszt Violina, a violin-playing orchestrion from a century ago. I took inspiration from its ingenious circular bow.

The Horse Wheel

The photo below is of the first horse wheel prototype. Our first prototype looked like a woolly mammoth and sounded a bit like one, too. As usual, Karl has taken my design and refined its proportions to make it more beautiful. The sandwiched maple and aluminum provide two types of strength. The holes will be filled with piano tuning pins which are used to stretch the short segments of horse hair.

That is one handsome horse wheel.  Photo by Karl Biewald.

That is one handsome horse wheel. Photo by Karl Biewald.

Adding the pins, Photo by Green Card Pictures

Adding the pins, Photo by Green Card Pictures

Tensioning the pins, photo by Green Card Pictures

Tensioning the pins, photo by Green Card Pictures

The Glaive

Within each of the three Horse Wheels is another structure called the Glaive. Each holds six tuned chalices and six small motors to bring each in and out of contact with the bow.

Karl designing the mechanisms.

Karl designing the mechanisms.

Karl testing the Glaive prototype, photo by Green Card Pictures

Karl testing the Glaive prototype, photo by Green Card Pictures

The Counter Rotation

Each Horse Wheel and Glaive spin in opposite directions. This uses the momentum of the Horse Wheel to maintain steady bowing as pressure changes. And rotating the chalices as they play creates stereo phasing effects and a small Doppler-based vibrato.

This video shows the counter rotation before we added the chalices.

Learning to Bow

Even after many tests and prototypes, we were still learning about the acoustic possibilities of the bowed chalice. Here is our very first test with the new wheels. We did eventually find much sweeter voices in the chalice.

The Finished Violina

The finished Violina from above.  Photo by Jenny Long.

The finished Violina from above. Photo by Jenny Long.

I am forever grateful to these kind and ingenious people for all of their assistance:

Karl Biewald – Mechanical Engineering and Fabrication.

Matt Nolan – Chalice Tuning

Marina Litvinskaya – Fabrication and Fine Detail

Laura Wickesberg – Electronics and Wiring

Nicholas Joliat – Software

Andrea Lauer – Set Design

Devin Budney – Fabrication

The Star Harp

In honor of the Stella Artois star, the Star Harp is a self-playing harp inspired by orreries, old mechanical models of the motions of the planets around The Sun. It uses the stem of the chalice as a bridge and the bowl as a resonator.

The Inspiration

The most finely-crafted orreries include the planetary moons. I started by looking at these mechanisms. The Harp form and other design decisions can all be traced back to these mechanical movements.

Modern Orrery 'Overweight Archie'

Modern Orrery ‘Overweight Archie’

The Harp

The form of the harp comes mostly from necessity. Its sheath of harp strings must be circular, so the machine’s five mechanical arms can reach each string. And the strings must connect with the soundboard at an angle, so both their transverse and longitudinal vibrations will sing in the sound board, making that harp-like timbre. We end up with a handsome and classic hyperboloid of revolution, a curved surface made from straight lines.

Hyperboloid curves made from straight lines.

Hyperboloid curves made from straight lines.

The First Paper Prototype

We start with a level zero prototype, a full-sized cardboard model. It’s a fast way to test proportions, design ideas and the spatial interaction of moving parts. It helps us identify and solve many problems before we start using the expensive materials later.

We start with paper or cardboard prototypes

We start with paper or cardboard prototypes

We learned:

  • The harp’s sound board would need to be bigger, for a bigger voice.
  • We should adjust the design for 15 gearwheel rings instead of 18, so each gearwheel can be wider and stronger.
  • The software will have to be very smart to keep the arms from colliding with each other.
  • This instrument was going to be a real looker.

The Hubristic Death First Wooden Prototype

Prototypes answer questions. Often question you hadn’t thought to ask.

How would this complex harp geometry sound and hold up with the tension of 60 strings? We built a stronger prototype with steel and inexpensive woods. The idea was to use 60 strings under the same tension, so they’d have similar timbres. Bridges would divide them into different lengths, following the harmonic curve found in the harp of a piano.

We started with the thinnest piano strings that could hold the tension without snapping. The first few sounded amazing. Why don’t we always use metal strings on harps? I did a quick calculation of the tension using the Taylor Formula. It reported that the fully-strung harp would have to withstand over 1000 lbs of tension. I loved the sound. It wasn’t clear how to calculate the strength of our carefully balanced design. I thought we might just get away with it.

With about one third of the strings on, the prototype warped and imploded! So … math is right. Sorry, no photo. It was a rough moment for Marina and me. We discovered we were still in the forest.

The First Gearwheel Prototype

The Star Harp’s 5 floating arms are mechanically driven by 15 concentric gearwheels. The gearwheels, the largest of which is 8 feet across, must be perfectly round and move with no noise or vibration.

This first prototype was pretty jittery. But it confirmed that the whole mechanism – drive gear, rollers, capstans – generally worked.

I later got it silent by replacing the rollers with slabs of a slippery plastic called Delrin. Now they all just gliiiiide.

The Final Harp Prototype

We applied the lessons we’d learned to what we hoped would be the final prototype. This final harp was made of high quality spruce tone wood, thick slabs of maple, stronger steel tubing, and a homemade layered composite of maple veneer and epoxy.

The harp resonator must be strong enough to hold the tension of the strings and light enough to vibrate freely. We tried to solve this with precise geometric structures. Here, Marina and Jenny are building the resonator:

Marina and Jenny create the delicate inner structure of the harp resonator.

Marina and Jenny create the delicate inner structure of the harp resonator.

The Second Arm Prototype

The arms of the Star Harp each have an elbow and wrist, which are driven by the turning of the gearwheels on with side of its mast. This report gives a peek into the prototyping process.

In the following prototype, I learned to mount the sprockets to the axles by first freezing/shrinking the axles and heating/expanding the sprockets with a torch. It produced a very clean-looking connection. But each time, there was only one chance to get it right!

In the end we made four generations of arms. The final arms copper counterweights, drive chains, and hand-crafted bearings.

Making The Gearwheels

Making the full set of gearwheels required cutting 90 precise wooden rings by hand. It took about 10 days and I was often ankle-deep in sawdust. As I was cutting, Marina was carefully assembling them in layers, which must have taken two or three weeks, as 75 layers had to be individually glued overnight like this:

Gluing the rings.  Or a wooden particle accelerator.

Gluing the rings. Or a wooden particle accelerator.

Once assembled, they had to be made perfectly smooth and round. Marina invented a good technique for the largest gearwheels:

Marina put a lot of dust masks through their paces!

The Glass Picks

The stem of the Stell Artois chalice makes a beautiful glass pick with which to play the strings.

Like starry little fishes.

Like starry little fishes.

Putting it all Together

Here is the second-to-last prototype, just before adding the steel gears and arm hardware:

The second to last prototype

The second to last prototype

Aligning the Gearwheels

The gearwheels must be perfectly centered on the 8ft. table, precise to about 1/16th of an inch. We did it old-school style, like da Vinci might have, with just hands and eyes and geometry.

Here, Ranjit helps with some precise measurements:

The First Two Arms

It was a long road. But here are the first two arms moving. You can see the interaction of the big gearwheels with the pair of gears at the base of each arm’s mast.

The Software

This may be the most complex software I’ve ever written. It takes a musical score as input and composes a choreography for the mechanical arms, a pre-computed set of motions which pluck the score on the strings. All the software can see is the current time and rotary positions of the 15 motors under the table. Everything about the motion of the arms, including collision avoidance, must be inferred with polar geometry and lots of pre-measured calibration. I spend the first night counting the gear teeth and computing ratios. The biggest gear has over 2500 teeth!

Mechanical Arms Completed

First Working Version

This amazing documentation by Green Card Pictures features the final two prototypes.

I am forever grateful to these kind and ingenious people for all of their assistance:

Marina Litvinskaya – Artist and Master Fabricator

Jeremy Bloom – Gear Wheel Assembly and Alignment, Fabrication, Good Vibes

Ranjit Bhatnagar – Gear Wheel Assembly and Alignment

Nick Yulman – Gear Wheel Assembly and Alignment

Jenny Long – Harp Assembly and Musical Arrangement

Karl Biewald – Gear Wheel Assembly and Alignment

Collaboration with J.Viewz and Manu Delago for Snapple

This instrument was an equal collaboration between Marina Litvinskaya and me.

The rainmaker overhead looks like it should have a brain in it.

The rainmaker overhead looks like it should have a brain in it.

The Ripple Tank below works beautifully with lights that color the edges of the ripples.

The Prismatic Ripple Tank which catches the raindrops uses colored light to show the edges of the ripples.

Marina testing the Ripple Tank.

The Rainmaker and Prismatic Ripple Tank. So rain sensors or sound yet.


The first of Marina’s complications, which redirect the paths of the falling droplets and change their rhythms.


Marina bravely tests (“apes”) the strength of the new prototype mast. Best collaborator ever.