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How to Make a New Wave Biradial Horn
How to Make a New Wave Biradial Horn
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Old 2nd December 2017, 10:40 PM   #1
Patrick Bateman is offline Patrick Bateman  United States
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Default How to Make a New Wave Biradial Horn

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Here's a few "classis" biradial horns.

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While pondering the JBL M2 and the JBL progressive transition waveguides (1) it occurred to me that there's a way to make something similar to those, but not quite the same.

One thing that's cool about this method is that it's exceptionally easy. Some of my waveguide designs have taken as much as sixteen hours to draft, but these are fairly easy and approachable to someone new at 3D. (If you've seen my 3D printed synergy horn designs, I have to manually 'drill' every single bolt in three dimensions and that takes fo-rev-er.)

(1) JBL M2 for The Poors
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Old 2nd December 2017, 10:47 PM   #2
Patrick Bateman is offline Patrick Bateman  United States
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Click the image to open in full size.

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As illustrated above, we create four hemispheres and we bond them into a single solid. The diameter of each hemisphere should be approximately as large as you want your waveguide to be. For instance, I'm using a 25cm wide hemisphere to achieve a 25cm wide waveguide. (Again, this is approximate.)
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Old 2nd December 2017, 11:03 PM   #3
Patrick Bateman is offline Patrick Bateman  United States
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Here's one of my favorite tricks when I make waveguides. If you space four solids by 25.4mm apart, combine them, then smooth them, you get a 1" round throat. This is because the process of smoothing the solid turns the square throat into a circular throat.

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You can see this same trick used in the QSC waveguides to get an absolutely perfect transition from round at the throat to rectangular at the mouth.

Once you fiddle around with this, you'll see there are ways to do this with a throat that's perfectly matched to the exit of the compression driver. For instance, you can bring the solids closer together than you normally would, smooth the throat, and then thrust a cylinder through the throat to match the compression driver.

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Here's the throat after smoothing. And then I trimmed the excess parts of the hemisphere.

You could leave it at this, and have something similar to the older biradials:

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But most will want something more compact...
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Old 2nd December 2017, 11:22 PM   #4
Patrick Bateman is offline Patrick Bateman  United States
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What if you took an oblate spheroidal waveguide

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And a biradial horn

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Then merged them together?


Note that this one could be tweaked quite a bit. You could have the biradial curve merge with the OS waveguide curve at any point on the biradial curve. (Because the biradial curve is a full 90 degrees.)
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Old 2nd December 2017, 11:57 PM   #5
Patrick Bateman is offline Patrick Bateman  United States
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As noted in post #3, most people will want a waveguide that's as small as possible.

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Here's a biradial horn that measures 25cm x 25cm x 16.5cm. (9.8" x 9.8" x 6.5")

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Here's how that horn looks if we just truncate the entire face of it. The size has been reduced to just 12cm deep. That's 27% shallower than before.

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If we smooth that horn, we get this. And now it's starting to look a lot like a progressive transition waveguide. Perhaps the PT waveguides are basically biradial horns that have been truncated and smoothed?

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JBL Progressive Transition Waveguide for comparison. Note the 'sharp' cutoff where the horn curve has been truncated.
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Old 3rd December 2017, 07:51 AM   #6
ICG is offline ICG  Germany
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Why not using something someone already made?
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Old 3rd December 2017, 07:54 AM   #7
Upfront is offline Upfront  Australia
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Quote:
Originally Posted by ICG View Post
Why not using something someone already made?
Where's the fun in that?
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Old 3rd December 2017, 08:24 AM   #8
ICG is offline ICG  Germany
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Quote:
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Where's the fun in that?
Where's the fun in making something, putting effort into it and on top of that, pay more?
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Old 3rd December 2017, 08:28 AM   #9
Upfront is offline Upfront  Australia
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Quote:
Originally Posted by ICG View Post
Where's the fun in making something, putting effort into it and on top of that, pay more?
Learning something new. Developing skills and knowledge. Somethings are hard to put a price on. I don't agree but I understand where your coming from.
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Old 3rd December 2017, 12:15 PM   #10
LewinskiH01 is offline LewinskiH01  Argentina
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Patrick,

Good food for thought. Thanks for posting. Which software do you use for this modelling?

Another reason for doing it is if no commercial options were available. Like I'm exploring use of a 2" CD on a constant directivity horn that can be used down to 400Hz or so, and with a rectangular form factor to allow tweeter above.
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