This post might not make sense yet

None of this is likely to make any sense right now, but it hopefully will soon. I'm just trying to get some thoughts published so I can come back to them later; I might actually edit this post into something coherent as well.

Large diaphragm diameters pose some problems both for fabrication and for operation. Flow rates, diaphragm materials, and attack quality are all problematic. Being able to use a smaller diameter of diaphragm while keeping a large horn diameter could solve some of the problems.

An air horn has a pressure peak in the middle, which is also a flow node (point of minimal air movement). This may be relevant to changing horn diameters; since PVC couplings create a discontinuity in the diameter rather than a smooth taper, it might be necessary to ensure that a change in diameter is made where the flow is at a minimum, to avoid losing amplitude as compared with a horn that's full diameter for its entire length.

The discontinuity could cause the horn's attack to be weird or unpleasant, and large enough changes in diameter could actually cause the horn to not work properly at all. I need to test a couple of things:

1. horn with significant diameter change at half-length (ex. 1" to 2")
2. horn with same diameter change but near the diaphragm end (much less than half-length)
3. horn with extreme diameter change at half-length (e.g. 1/2" to 2")
4. if 1 and 2 have similar tone and volume, try extreme diameter change near diaphragm end