EnABL the horn's mouth?

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Where is the thread describing someone's efforts to apply the EnABL pattern to the mouth of a horn? I'm sure it has been tried, but the search phrase "EnABL mouth horn" only turns up a precious few threads!

Perhaps I haven't read carefully enough the descriptions of the EnABL process, or I misunderstand how it works. I think, in a nutshell, it has something to do with the way the wave of energy is transferred from one material (the driver cone) to another (the air). There is an inherent, abrupt and unpleasant impedance mismatch here. A lot of the energy fails to "shake loose" from the cone, and gets reflected back down towards the voice coil. No end of foolishness results (inefficiency, cone breakup, etc).

After reading a bit, perhaps a similar event occurs in most horns? The size of the mouth is "compromised", and cannot be as large as it ought. There is an impedance mismatch, and a resulting sonic shock wave occurs where the front tries to escape from the mouth. I would think applying some kind of EnABL pattern (on a larger scale) might be helpful here. Maybe if I had more than a few dozen stick-on cork or rubber feet, and decorated all around the mouth...

Am I getting this all wrong?

edit: never mind, it seems all the discussion is in Multi-Way. No sense creating a clutter here...
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Hi Ty,

Not many folks have tackled horns. Alex, myself, Romy the Cat, are ones I know of off the top of my head. If you would like to experiment you might PM me.

What I will say here is that you only need clear acrylic plastic (or vinyl) shelf paper. The stuff is 3 mils thick and easily removed. A number of patterns are needed.

One at the throat entry, a couple down the walls and one near or at the final flare or edge roll. The ones along the horn curvature need to be found with the same means with which we now find resonance nodes on direct radiators.

We can either carry on in this thread or move over to the official listening and practices thread, your choice.
I've been thinking along similar lines recently after reading about the Frugal-Horn and horns in general as to how to get a horn mouth to operate at a lower cut-off frequency than the simple wave equation would dictate.

Rather than enable, what I was looking at is a phenomena called Extraordinary Acoustic Transmission (EAT). It hasn't been applied to audio yet. The idea is to reduce the impedance mismatch between the horn and it's environment. EAT has been shown (e.g. by adding a 1-d grating which would be like a set of bars across the horn mouth) to allow the transmission of lower frequencies than would otherwise be the case.

Maybe something for MJK to look into...

The first link doesn't provide anything to my browser. Is there another?

The second is very interesting. I assume it works as a dither mechanism and settles the energy into the least loss, most coherent format. This is similar to what EnABL does, though we are providing the driver and concentrating surfaces with a control mechanism that would still be needed, unless these mechanisms shown can completely suppress the loop back feedback mechanisms at work, on both the emitter and focusing surfaces. I view the cone on a direct radiator as a "live wall" horn surface, even though the transverse wave energy in the direct radiator is of a different magnitude than that found in an inert horn.

I am sure there are official words that are supposed to be used to describe these effects and I apologize for not knowing them.
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