Date: Tue, 5 Nov 2002 13:25:13 -0800

Author: Bill Alexander

Subject: RE: Flame tube


I believe that if you enclose the area behind the speaker, it will greatly
reduce the sound pressure in the tube, since the enclosure will not allow
the speaker cone to move freely. What I did on ours when it caught fire
was seal the end w/ a section of plastic bag, flexible enough that the
sound goes right through.

>Improvement suggestion:
>It was suggested to me that I might make an airtight enclosure for the speaker
>so that no gas leaks through the surrounds. 'Sounds like a good idea because
>gas definitely leaks out there (I've lit it) and there is noticibly less
>flame-height at the speaker-end because of this leak. My thought is to use
>a cylindrical piece of tupperware, cut the bottom out, mount one end to the
>back of the speaker, and put a rubber diaphragm over the other end. This
>would also allow you to slap the rubber to do a 'pre-demo' buildup if you

>>I'm interested in building a flame tube -- basically a large "gas grill"
>>with a speaker in one end that shows standing waves by the corresponding
>>heights of the flames. I have a student who has the know-how to build
>>one, but we'd appreciate any information & advice -- or, best of all,
>>some plans! In particular, we're wondering whether anyone knows anything
>>about choosing the hole spacing and diameter.


Bill Alexander Excuse me if I ramble,
Physics Dept. but I drive a Nash.
Humboldt State University
Arcata, CA 95521

phone: (707) 826-3212