» MAKE: NOISE — Discuss this article

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• 9/16ths Drill Bit
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  HomeDepot and Lowes don't seem to have them. Any other places I might check?

  Posted by helldaemen on June 15, 2011 at 16:20:50 Pacific Time

• Pipe material question
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  If this is the wrong Place I am sorry. I would like to know if is could us galvanized steel. I am assuming no but is is so much cheaper than the other options around me.

  Posted by sjstuder on June 09, 2011 at 18:18:16 Pacific Time

• Alternatives
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  On the speaker, an elegant solution I found other than the witch hat was to purchase a 4"x2" pvc reducer and cap (make sure it's one for a fitting and not for a pipe) that fits over the reducer. I drilled out two holes for banana plugs, throwing in some flexible glue similar to hot glue to seal it. I put in a 4" speaker (bending back the mounting bracket slightly to fit, wired it, soldered it, and closed it in (sealed with pvc cement). A very small section of 2" pvc pipe is needed to marry to the conduit with a end-to-end clamped connection. Use a rigid type with a piece of tempered metal around the rubber part. On the stand, I just used a plumber's hole saw in a painted section of 2x8. I loved the idea for ptc fittings and tapping the sides with the 3/8" NPT, worked beautifully. (although my natural gas leaks through this when turned up high). Finally, replace the helium balloons with a $3 cap and clamp on the non-speaker side. My speaker setup was sealed, so no cap needed on that side. Your speaker needs to be amplified and not from a headphone jack; the 1/16" holes may need to be enlarged (slightly) for natural gas pressure in a science classroom. Thanks for this article!!! I've been scratching my head over this for years.

  Posted by MrHagstrom on April 28, 2011 at 11:45:08 Pacific Time

• Alternatives
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  My leak was in the push to connect fitting, NOT the threaded fitting in the conduit, and only ignited when my gas was on high. I'm using natural gas from science lab station. I also had this connection (the T) too close to the pipe, so the vapor from the small leak was ignited by the tube. I'm experimenting with larger holes in the tube itself, so I don't have to have the pressure up as high. It's crucial that the speakers get plenty of power, nothing special with equipment, but just not from a headphone jack. I'm new with ptc connections, but I think I can seal these up just fine if I need to without changing to copper or something. Again, a big thanks to the author for making this a lot cheaper than I was originally thinking and for the well-written instructions. One change I think I would make (if I were to start over or do this for the first time) would be to use a slightly larger tube length and drill the holes just slightly closer together.

  Posted by MrHagstrom on April 28, 2011 at 12:33:20 Pacific Time

• Update
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  The reducer I mentioned above is a bushing, so the cap fits right over it with no need for 4" pipe. Everything snugs up with the speaker inside, into a small space, the size of the cap. By putting one on both sides of the tube, the flames that were hard to keep going on the speaker side are no longer a problem.

  Polarity does matter with two speakers so make it switchable with your plugs, or check before you close it up. I used panel mount banana jacks put into the SIDE of the cap near the back.

  I get flame heights (differences) now that are quite impressive with two cheap speakers (running off the SAME side of the amp).

  Surprisingly, 80's guitar music is not the best to demonstrate. Hey Ya!, A Little Less Conversation, & Elvira (yeah) are very good. Anything with very strong beats. I run the music through my desktop speakers for quality & normal volume, and only one channel of the receiver that the computer is hooked into Otherwise it would be way too loud.

  Excellent nodes & antinodes from 100 to 1500 Hz from a frequency generator, almost nothing over 2000 Hz.

  Posted by MrHagstrom on May 15, 2011 at 19:12:26 Pacific Time