Acoustic Lens

[whgeiger]

To begin this thread, I have posted the work of Koch & Harvey (1949) which will hopefully form the basis for contributions from others here. Important to loudspeaker design is the divergent lens variant that may be used to mitigate narrowing of the radiation pattern exhibited by direct radiator and horn loaded drivers at their upper frequency bounds. Later I will post a bibliography of the works of others in this area.

Merry Christmas & Happy New Year to All,
Regards,

WHG

[Tom Danley]

Thank you Bill.
That is a nice collection on a little discussed subject.
I had hoped to link something new but I don’t see the application is visible yet at the Pat office so I can’t show it yet. It is a lens like thing which takes the outputs of multiple compression drivers and produces the wave front that would have been the result of a single source, without the interference pattern / cancellation nulls normally found on Y or manifold approaches. It is used in a couple large scale horns we make at work.
These two might be of interest though as these are in use now in commercial sound.

Patent US20090323996 - Horn-loaded acoustic source with ... - Google Patents

Patent US20090323997 - Horn-loaded acoustic line source - Google Patents

An off topic question. A long time ago (10+ I am sure), you used to post on an obscure horn / loudspeaker diy website (maybe European) . When my computer HD crashed back then, I had lost all of bookmarks and so on and could never remember the name. Anyway, your posting here now reminded me of that old frustration and loosing that web site, well it doesn’t matter now I guess.
Best Regards,
Merry Christmas

Tom Danley
Danley Sound Labs

[Ron E]

That plano-convex is a work of art - I might make one as a curiosity some day. These devices don't seem to have the best dispersion characteristics (refractive index varies a lot with frequency), a compound design might give an overall new meaning to the term 'achromat' though.

[speaker dave]

Originally Posted by Ron E

That plano-convex is a work of art - I might make one as a curiosity some day. These devices don't seem to have the best dispersion characteristics (refractive index varies a lot with frequency), a compound design might give an overall new meaning to the term 'achromat' though.

Figure 14? Yeah, I thought the same thing, beautiful.

David S.