# The Pyro Board: A Two Dimensional Ruben’s Tube

Like visualizing music? Love fire? If so, you’re going to want to take a look at this Pyro Board.

What happens when you take a tube, put some holes along it, add a speaker on one end, pump some propane in, and then light it on fire? You get an awesome fire visual — also known as a Ruben’s Tube. It works because the sound pressure from the speakers causes the flow rate of gas leaving the holes to vary, which results in a visible “standing frequency” of flames, i.e. a flaming VU meter.

The folks over at [Fysikshow] decided to step it up a notch by building a 2-dimensional Ruben’s tube with 2500 holes. They have a steel box with the evenly spaced holes on the top, and two speakers attached to the sides. And it works amazingly well — see for yourself after the break.

Based in Denmark, [Fysikshow] travels to schools teaching kids about physics using the Pyro Board and many other fun experiments.

[Thanks Eren via This Is Colossal]

## 36 thoughts on “The Pyro Board: A Two Dimensional Ruben’s Tube”

1. zibri says:

very nice idea, but too much interference.

1. tim says:

this whole thing is about interference.. standing waves are interferance of waves of constanty equal frequencies..

1. John Smith says:

Technically yes, but you know exactly what he meant. The is too much spurious ‘signal’ (flames) and the board fails to show a good representation of standing waves. This could be to bad gas flow, or maybe even weird reflections in the square corners of the box.

2. AussieTech says:

Interesting display, but this is NOT an “equalizer” FFS.

1. Again with the “equalizer”! Every god damn time!

2. kristian says:

In the visualizing music department, you might be able to make a ruben’s tube with an inverted horn, so you’d have different sections responding to different frequencies.

1. I have been looking to understand what an inverted horn speaker is. I assume you mean the old HMV type gramaphone tubes that amplified sound produced from a needle on a record. So could you elaborate on what you mean here . How would you apply this gas and sound input to such a speaker?

3. AlanH says:

It’s pretty insane now. However if you fine tuned a series of band pass filters going into the box to get rid of most of the noisy intermediate node frequencies, it could be more spectacular. One could make a nice living building, tuning and selling these to clubs, ski resorts, and other social businesses all over the world (as long as you were insured and bonded!)

1. AlanH says:

My guess is it might be more successful with a round base so you never get an orthogonal reflection. To me it seems waves would better propagate and constructively amplify at the right note if you interjected them at an angle and they bounced around a circular perimeter. However I assume the guy likely tried it already and this is the shape that works best.

4. JustSo says:

They set up a big, experimental flame machine in a bedroom! Awesome, and none of the schoolkids will ever forget the standing waves.

5. freelancer says:

Absolutely love it!

6. Greenaum says:

I think the 2D-ness robs it of the impressiveness a Ruben’s tube has. Watching waveforms pump out along a Ruben’s tube, standing wave or not (in fact, “not” looks better) is immediately impressive. Particularly with bassier sounds where you can literally see sine waves made of flame.

A Ruben’s tube is pretty much 1-dimensional, so the waves look like they do in textbooks, really wave-like. I think the nature of the 2D thing, letting them spread out, and the interference, spoils the effect quite a bit.

OTOH might be a nice effect in a nightclub, or at Burning Man or something. Presumably kept in a strong glass case, for safety.

7. Greenaum says:

The grid gives me another idea though. Do you think, maybe with thermostats or valves of some kind, you could do something like Conway’s Game Of Life on one of these? With lit cells being “alive”. Conway’s rule just needs to sum up the living cells to decide the next generation, shouldn’t be too hard to match that to a certain amount of heat input.

Maybe it’s harder than I think, maybe it’ll get too warm eventually and stop working. Just something that struck me watching the tiny flames moving round a grid.

1. It looked like it actually was already playing Conway’s Game of Life. There are finite resources of air and fuel, and if too many flames were in one location, some would go out. Other flames that happened to be near a resource-rich area would start new flames there.

8. David says:

The tube is named after Rubens. Why is there an apostrophe in there? Oh yes, the story was by Jame’s Hob’son.

1. rj says:

It’s like the advice the tour at Johns Hopkins gave me when I was looking at colleges: placing any apostrophes in their name was a sure-fire way to guarantee you would not get admitted.

9. A triangular or trapezoidal Rubens plate would have different resonances along its length – a DFT with fire!

10. tom says:

Plus it heats the apartment!

11. Thats a brilliant way of teaching young ham radio operators what Standing Waves are!

12. Hirudinea says:

Ok, call me weird but with tighter control this would make the most badass cook top ever!

13. steve says:

Love this

14. That one guy says:

A flaming VU meter? FAAABULOUS!

15. I may have missed something, but I’m thinking that oxygen starvation would be an issue in a 2D array. If the flammable gas was premixed with oxygen, it should work better.

1. Hmmm… Good point. Paired tubes, then? One for gas, one for oxygen?

1. Jay says:

You do not want to have an oxygen input. The flames get oxygen when they come out of the tube. If mixed in the box it could explode.

16. Galane says:

What would be really impressive is a round one that could do circular standing waves.

1. Kam says:

Any one done this? That’s what I’m thinking of! It would be interesting to see if you could get standing waves of different diameters to propelgate at different frequencies, the radial waves would be so much cooler!

17. Jerzee says:

I wonder how a cube would work to include surround sound input.

18. Sean says:

Hey how much will you charge to make one???? That shit is tight I have a pyro Board but your is beast

19. sharma says:

I was planning on making one of these for a science fair project. But building it has been kinda stressing. Any suggestions please .

20. Taylor S says:

I’m looking to make this for my senior project next year, I was wondering what kind of systems & set ups you used? Any tips or advice would be helpful thank you!

21. Kirk Geahlen says:

Anybody know the exact specs(Table size,hole size,hole spacing,speaker size,speaker power,etc)?I’d sure like to replicate it.It’s awesome!

1. Marius says:

Hello Kirk Geahlen
I would like to make and rebuild this thing as a project. Did you find any details? If so, I would be very happy to receive an answer.

1. Benjamin Morel says:

I am interested in building it too. I have the time to, but not everything else.

Since there are 2500 holes, the surface would be 50 x 50 holes. They are evenly spaced apart, we just need a measurement.

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