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Patrick Bateman 3rd August 2012 10:55 PM

Square Pegs

On this forum, Tom Danley has given us some information on some interesting new ways to fold a horn. These new horns include the VTC Paraline, which combines two compression drivers on one horn, and the Jericho J4, which uses what he calls a 'layered combiner' to load 64 compression drivers on one horn.

Unity Paraline - YouTube

I decided to build one this week.

Once you figure out how they work, they're a lot of fun to build. They're waaaaaaaaaay easier to assemble than a Synergy horn, that's for sure. I built this one in under two hours.

The device that I built is neither a Paraline nor a layered a combiner. For the most part, it's a simplification of the Paraline. (I could build a *real* Paraline, but I didn't want to for this project, I wanted to do a 'proof of concept' first.)

As usual, my projects are completely kludgey and rushed and crude, but you get the general idea.

In the video, I think you'll notice a few things:

#1 - Although my compression driver appears to be firing through a block of wood, I have extension out to at least 18khz
#2 - Have you ever seen a horn that was less than four centimeters deep?
#3 - Have you ever seen a Unity horn that was smaller than a 8" woofer?

Hope you enjoy the vid.

ra7 3rd August 2012 11:09 PM

Cool video! VERY VERY interesting.

Will you be showing how you built it? I wanna try one.

Patrick Bateman 3rd August 2012 11:12 PM


Originally Posted by ra7 (
Cool video! VERY VERY interesting.

Will you be showing how you built it? I wanna try one.


Mine is way easier to build than a Paraline, but it's the same idea.

Everything you need to know to build this is in the Paraline patent. AFAIK only Danley has built one with the midranges on the Paraline, but it seems to work fine that way.

I'll upload some pics later this weekend, which show the internals of the thing.

konut 4th August 2012 02:17 PM

Absolutely fantastic! Looking forward to the details.

Patrick Bateman 6th August 2012 10:15 PM

Here's another video, showing how I am folding my Paraline-type device:

Paraline Folding - YouTube

The radiation of the Paraline is basically an ideal match for a ring radiator. The high frequency output of the Paraline seems to be far superior to a conventional conical horn. (For instance, with the same driver on a conical horn, my horn seems to run out of steam at 2khz. On a Paraline, the same midrange driver seems to go to about 5khz, well over an extra octave.)

Anyways, check out the video, I think it explains the folding in a understandable way.

I'll post some pics of the device assembly in the next couple days.

Patrick Bateman 6th August 2012 10:22 PM

Here's some more food for thought.

In my Paraline-type-thing, I have a square throat. One drawback to a square throat is that the output from one side could create comb filtering with the output from the other side. If you look at the Danley Paraline in the VTC Array, Danley has placed a phase plug in the mouth, which should reduce this problem.

But here's an idea of another way you can solve the problem.

You lay my Paraline-type-thing on it's side and now you're radiating in 360 degrees. Somewhat similar to the Duvel speaker pictured above, but in a foot print that's less than 1.5" deep, and much much much easier to build.

(Again, I built my Paraline-type-device in under two hours. It's super super super simple to build.)

I am listening to it this way right now, and it works very nicely as an omnipole. Seems to deliver the 'room sound' better than a typical speaker does.

As always, if this post makes no sense, please let me know. This Paraline thing is a bit mind-bending, and it took me a few weeks to grok all of the math. In my pic above, the idea is that the sound radiates in a ring inside the Paraline, and then at the Paraline mouth we create another ring radiator.

This harkens back to the traditional Unity horn concept of a conical horn stacked on a conical horn stacked on a conical horn. Except here we have a ring-shaped horn that feed *another* ring shaped horn. You could continue this across the entire frequency bandwidth. For instance, you could have tweeter, midrange, and low frequency all radiating in a ring.

Nissep 7th August 2012 10:55 AM

My understanding of the paraline is that the sum of the diferent pathlenght is always konstant if you dont want it to have a different shape of the waveform as i leaves the exit.

A neat trick you can use is to use a small lenght of string and fold it in half. One end you attach i the middle of the divice, the entrance for the speaker. And the other end of the string you move around on the edge of the shape of the exit "port".
And with the string folded and pulled straight out from the middle you will get the shape of the first cutout. The shape of the exit dont matter as long as the patch lenght is the same.
And a string cant change its lenght..

DrDyna 7th August 2012 12:32 PM

I'm looking forward to construction pics. I haven't experimented much with horns but this one looks easy enough to try with wood scraps I have laying around.

layhzer 7th August 2012 03:32 PM

Great videos. Folding paper is a simple and elegant way to convey the idea.
As much as I value the contributions of experts like Earl Geddes, Tom Danley, Speaker Dave, John K... and others, it is your posts that really get my brain cooking. I see the Paraline as a device to change the radiation pattern of a driver to fit new environments.

How about this for radical? My listening room badly needs a new floor.The "temporary" floor has been in place for 25 years. How about a low frequency Paraline built into the floor with a 16 foot long exit slot running the length of the room? This should provide a different excitation of room modes than a single point source. Better maybe. Worse perhaps.

Not radical enough? How about a tapped low frequency Paraline. The same as above but using the radiation from the back of the driver to aid the radiation from the slot.

Still not radical enough? I know a low frequency Paraline won't act exactly like a double bass array but what about a "launcher" Paraline on the floor and a "catcher" Paraline on the ceiling.

Other than the obvious issues, the real problem is modelling the performance of the system. Anyone know of any tool that would help with this type of analysis?

ra7 7th August 2012 03:51 PM

Patrick, call me dumb, but I just don't understand how it works. Maybe some construction pics might help.

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