Line Source Horn Designs?

[neededandwanted]

I started a new thread on this because it didn't really seem to fit into any of the Line Array / Line Source or Horn threads already in existence. I certainly didn't want to hijack an existing horn thread or ribbon line source thread to go off on this tangent.

Basically, I am looking for any info about existing line source horn designs. (To clarify: any horn designs that would allow a horn to emit a flat, line source wave, as if it were a stack of closely spaced drivers - very closely spaced for high frequency sounds - or a ribbon or other planar driver)

One such waveguide arrangement is shown here
(about 75% down the page):
http://www.lenardaudio.com/education/07_horns_3.html
This is basically just making a wiggling path in the center of the horn or waveguide, so that the point-source compression driver at the throat emits an apparent line source wave at the mouth. In this way, the waveguide acts as an acoustic "lens" to make the center path longer, effectively slowing down the sound coming out of the middle of the horn, while restricting the sound coming out of the top and bottom of the horn much less.

I had also seen a somewhat similar "squiggle and split" pattern for a horn somewhere on the DIYaudio board - an actual image posted here - but I have not managed to find it again in any searches recently (anyone know where that one is here?)

Another waveguide shape is shown here (look on page 5 in the center):
http://www.sonicdesign.ch/downloads/...ine-source.pdf
This one is from L'acoustics for use in PA system Line Array cabinets.

Another PA cabinet line source horn arrangement is the "Ribbon-Emulation Manifold" from MeyerSound. While it does not really provide a continuous true linesource, if does effectively split the horn into 4 coherent emissions through the use of a (patented) funny split horn:
http://www.meyersound.com/support/papers/REM/index.htm

Another PA emulation is here:
http://www.renkus-heinz.com/loudspea...hite-Paper.pdf
That document explains quite a bit about acoustic lensing for line source use and has some simplified functional images of their horn/waveguide design. (Though I would love to see exactly what is really on the inside of those horns)

Another PA embodiment is here:
http://www.orbitalsound.co.uk/sales-...db-tseries.asp
This one actually has a rotatable waveguide plus acoustic lens arrangement that allows switching between line source and point source emanation patterns.

So, who knows of other designs for this? Pictures, patent applications, etc. I'd like to see anything anyone is doing in this direction for home audio or professional sound reinforcement. Any design where a (compression) driver get bolted on to the back of a horn and results in a line source "cylindrical wave" coming out of the front.

Has anyone here actually ever played with any such thing personally?

[MaVo]

Something like this? http://www.danleysoundlabs.com/pdf/G...0beginning.pdf

[neededandwanted]

Originally posted by MaVo
Something like this? http://www.danleysoundlabs.com/pdf/G...0beginning.pdf

Well... I don't know, actually. I have no idea what's on the inside of Tom Danley's latest breakthrough. I have been wondering about the GH-60 since I saw the picture at the bottom of the page here:
http://www.danleysoundlabs.com/pdf/G...%20Summary.pdf
(below all of the very impressive graphs)

Anyone have any autopsy photos? What is IN there? [note to Tom Danley or Mike Hedden: sneak me some pictures and I promise I won't divulge or imitate...]

I have been a huge Danley fan since "Elephant Subwoofers" thru ServoDrive thru Tapped Horns (including the Matterhorn) and Synergy Horns. I guess the Genesis is the next super-efficient miracle.

I also really admire the fact that he shares enough information on his discoveries for the rest of us to start playing with our own designs using his principles (but without a complete "recipe" that gives away the farm and injures his commercial ability to keep innovating).

Since Danley's stuff tends to be all point source gear (and compete very well against line arrays even in their preferred battlefields, I am going to assume that the GH line will not have any line source components.

I DO really want to know what is really going on behind the scenes there. Paraline Lens Technology? Shaded Amplitude Lens Technology? If I had seen those "patent pending" terms anywhere else I would have likely dismissed it as marketing fluff, but based on the track record, I know there is some sound science behind it.

"Paraline" sounds like some sort of line source trick, so maybe it does fall into this thread. "Shaded Amplitude" sounds like some sort of cool coverage control technology (maybe a bit similar to the acoustic lenses of many years ago?)

Thanks for the link to the white paper, MaVo!

[Pano]

Or something like this?


photo from Melaudia.net

[neededandwanted]

That looks like a horn-loaded line array for the LF sound for sure. Very cool-looking room, and makes me wonder about actually living inside the mouth of a giant horn. (or even living in the compression chamber)

BTW, if that guy is married and getting any high SAF on the system, his wife just replaced my "dream girl" definition (um... Guinness heiress, long fingernails...)

What I am looking for (and may not be explaining well) are designs where a single driver is mated to a horn/waveguide which results in a line source.

[neededandwanted]

Originally posted by MaVo
Something like this? http://www.danleysoundlabs.com/pdf/G...0beginning.pdf

OK MaVo, you have nailed it after all.

I found this on the Paraline system:
http://www.vtcproaudio.com/paraline.html

And a 3-D exploded sort of animation here:
http://www.vtcproaudio.com/paraline02.html

And some more details halfway down this document:
http://www.vtcproaudio.com/downloads/press/vtc_cat.pdf

It makes for a very "shallow" horn ("less than one inch deep"), but appears that the sound path has rather extreme angles to get around. I would love to hear one of these (or a floor to ceiling array). I would also like to know if this waveguide design could be made to work lower in frequency.

This one definitely falls into the category I was asking about. ("weird waveguide resulting in line source emanation")

[Pano]

Hmmm... strange beast indeed!

[neededandwanted]

Any more of these out there?

I'd love any pics or links to patents or patent applications.

I don't want to infringe on anyone's designs really, but I do want to start working on some line source horns - especially some with a bit of extended range. The ones for PA use seem to only be used from about 1kHz up (and sometimes only from 3500Hz up).

With all of the "full range" drivers out there, it might be fun to try making a live source horn that gets from, say, 400Hz up (or even lower).

It's sort of a cool alternative to just packing a million drivers in a line to get the spacing less than 1/2 wavelength from center to center.

[bear]

I have no idea what your real goal is... but take a look at how a Beveridge ESL is constructed. Maybe you can find some ideas there...

If all you want is a large smooth line source, why not build or buy a ribbon like the BG??

_-_-bear

[neededandwanted]

Originally posted by bear
I have no idea what your real goal is...

If all you want is a large smooth line source, why not build or buy a ribbon like the BG??

I have built, bought and borrowed ribbons, and love them.

For some reason, efficiency is becoming an issue for me lately. It is sort of a weirdness that we accept that a loudspeaker can be awesome when it emits 99% heat and 1% changes in barometric pressure. Some horns make it to 20% efficiency (admittedly at some cost).

Your statement about my "real goal" is valid, however -- I don't have one. As a small intermediate goal, I would like to see if a decent near-full-range line source horn can be made, maybe only because no one else seems to be trying it. I could spend 200 hours making another floor-to-ceiling ribbon, and get close to someone else's performance. It is a pretty straightforward exercise (not easy, and not cheap) and maybe if the cost of permanent magnetism comes down by about 99% we'll have them available at every Wall-Mart.

It's just a different direction I am looking in for a bit here. I originally had some ideas on a line source horn many years ago, and now see that several manufacturers in the sound reinforcement field are busy patenting their waveguide designs (that all seem to look like several of my old notebook sketches) and so I wanted to know what is currently the state of the art in this area.

Line Arrays are now the bandwagon that all PA manufacturers have now jumped on in "me too" fashion. They pretend it is some sexy new technology, and use it primarily for coverage control of huge arenas that are really bad listening rooms.

Horns in general are so cool, and some of them sound great. All of the good ones are point source devices, and I'd like to just take a look at making a line source one.