Styrofoam Smith Horn

[kenpeter]

Just screwing around with polystyrene... Seems to work!
But not yet tested with crossovers and rest of the system.

But the wood driver plate drifted off-center as the glue
was drying... I put a peg in the throat to try and fix the
center of dispersion (also seems to work).

I wonder most Smith horns I see built with overhanging lips??
This expansion is conical, not exponential, after the septums.
But why??? A conical expansion theoretically adds no loading,
and can't mitigate any HF sectoral beaming already created
by the exponential throats...

Future experiment will modify the top cover with sectoral
K slots (like JBL Aquarius). That begin an exponential slot
leakage about where the exponential throat area ends...

[fwater]

Just screwing around? Looks like a reasonably serious attempt to me.

I am not familiar at all with this type of horn, so here's a barrage of questions...

What is the range? Coverage? Is this a design intended for a particular driver, or can they be "rolled" through? Claimed advantages / disadvantages?

I must admit, my curiousity is mainly do to the quite serious and sleek look (i'm a believer that a speaker should look good as well as sound good), and of course, my curiousity of all things audio. I am becoming more attracted to the idea of high sensitivety two-ways to go with my unkown vintage / brand name / power output tube amp.

[pos]

Nice!
But your horn seems to be missing two half fins of the sides (and these actually make the expansion non conical)

If you do a search on the audioheritage.org forum you will find plans and spreadsheets for various versions of that horn.

[kenpeter]

Originally Posted by fwater

I am not familiar at all with this type of horn, so here's a barrage of questions...

You can read Bob Smith's 1951 Audio Engineering article here:
http://audioheritage.csdco.com/vbull...ead.php?t=9148

[freddi]

in mono it has a holographic sound with good subjective vertical dispersion - can't remember if I've run stereo but probably with 416 in K15 - there's my rock n roll bass

[defect9]

hmmm... based on the shadow characteristics, that picture looks like the fins extend to the edge of the horn

*edit* Nice "Rock n roll" guitar

[kenpeter]

OK.. Here's a sketchup of the basic idea...

Slots: acting both as plate lens for horizontal dispersion of sector beams.
And as Karlsons for continued exponential expansion of the horn mouths...

Or can just K the top plate only, sorta like JBL Aquarius...

These curves might be rounded the "wrong way" for a dispersion lens.
But artistically correct for a Karlson... Could split the diff and just cut
these notches triangularly? Somebody would surely poke an eye out...

[kenpeter]

Originally Posted by pos

Nice!
But your horn seems to be missing two half fins of the sides (and these actually make the expansion non conical)

Not missing. I simply cut an exponential throat in half. Sidewall is the middle.
You migh notice the mouths of those outside sectors are only half as wide.
My latest sketchup does show half fins as you describe. But either way works...

The conical part of concern is the perimeter. After exponential throats have
terminated "too early", and before reaching the edge.

[Pano]

Crazy looking horn! Would love to know how it sounds.

Isn't there often someone selling wooden ones on eBay?

[freddi]

IIRC there were two versions on ebay