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MEH - multiple entry horn for commercial purpose?

nas

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Hi,

Short version:
Want to build 2-way, 2 drivers total Multiple Entry Horn type speaker. Schematics is this:

multi_entry_horn.gif


It will be used commercially not for personal use and I will get reward for building them.

Long version:
There is a request to build some heavy-duty speakers on cheap and most likely in the way they will be used it matters very little what type they will be: the simplest way could be to build some Econowave type box, or reasonably sized BR or any other "classic" type boxes and call it a day, but my brain is itchy as this is an opportunity to learn something new. I see there
There are 2 most widely discussed patents related to this: https://patents.google.com/patent/US8284976B2/en?inventor=thomas+J+danley&oq=thomas+J+danley and expired one https://patents.google.com/patent/US6411718B1/en?oq=US6411718B1 but there are also many more commercial speakers with this principle made not by the inventor related company, so it get interesting: either they have commercial relationship or the patent is kinda... how to say... about nothing.

The questions:
-Can I build commercially such speaker?
-Will it change if there are 1,2,4 or another amount of low frequency (LF) speakers?

p.s. Like most of the people because of the specific language used in many of recent patents texts I don't understand much what is written there :(
 

Keith_W

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Why don't you buy an existing design? Red Spade PSE-144. Measurements (including directivity) here.

BTW I know the designer, he lives in the same city as me and I have seen the prototype of this speaker when it was under development. I have also heard a number of these speakers locally. The designer told me that he corresponded with Tom Danley.
 
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N

nas

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Why don't you buy an existing design? Red Spade PSE-144. Measurements (including directivity) here.

BTW I know the designer, he lives in the same city as me and I have seen the prototype of this speaker when it was under development. I have also heard a number of these speakers locally. The designer told me that he corresponded with Tom Danley.

Of course buying a complete product or plans for product (if available) is always an option, but... this is not the case this time: that Red Spade thing looks so much upmarket, that it may be over my budget at least 50 times. Plans for MEH is an option or any confirmed and reasonably documented DIY build. But I kinda want two things from it: to learn and understand actually what I am doing AND do not mess with someone's intellectual property.
 

Ron Texas

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Meh, that's an unfortunate acronym, LOL.
 

voodooless

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As long as you limit yourself to the unity patent, and not go to the synergy patent, you should be fine.
 
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nas

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As long as you limit yourself to the unity patent, and not go to the synergy patent, you should be fine.
Now we are moving into the twilight zone... What are the differences in those patents? I admit, have not read word-by-word both patents, but from pictures they are literally the same.
 

dwkdnvr

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Now we are moving into the twilight zone... What are the differences in those patents? I admit, have not read word-by-word both patents, but from pictures they are literally the same.
My take is that the Synergy is an evolution of the Unity that alters the geometry and xover topology so the entire multi-entry horn system becomes phase coherent / minimum phase.
I think it's an interesting question as to whether a Unity system that uses DSP to achieve the same goal would be infringing or not. I suspect not, but IANAL.
 

voodooless

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I think it's an interesting question as to whether a Unity system that uses DSP to achieve the same goal would be infringing or not. I suspect not, but IANAL.
I don’t think it might matter very much. Maybe if you use FIR filters, you have a way around it. But there may be other ways as well… start by reading the patent in detail.

I tried asking Microsoft Copilot, but it kept insisting that the Unity horn is a 2-way, and then got annoyed by me pointing out that that is nonsense and the have up. What a stupid tool :facepalm:. ChatGPT said that it didn’t know the patent specifics, and gave up, but at least was friendly ;)
 

DVDdoug

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For any speaker in a box I ALWAYS recommend getting some speaker design software. WinISD is free but it doesn't cover horns.... But still, you should optimize the "back-side" of the cabinet behind the horn. You enter the driver's Theile-Small parameters and the software will recommend the optimum box volume and port dimensions, or it can tell you if a sealed cabinet is better and optimize the volume for that. And you can play-around with changes to see how they affect performance.

I've never studied horns (or waveguides) in detail, but the effectiveness is related to wavelength (lower frequencies have longer wavelengths) and what you've shown, the horn looks too small to be effective for bass.

Woofers for deep bass have to be HUGE. They aren't really practical for anything portable (and in-general they aren't "practical"). Very large horns were used in movie theaters back when theaters were big and amplifiers were small. But they didn't go down to the subwoofer range.

When I was growing up in the 1970's the Altec A7 was popular with rock groups. (You can catch a glimpse of one in Saturday Night Fever.) It's got a "small" woofer horn, but the woofer kicks-in at 500 Hz (800Hz for some versions) so the "bass-horn" can be effective for some of the mid-range. For the deeper bass, the cabinet is ported but it's not really a "subwoofer" either. It starts rolling-off below around 50Hz.

The famous Cerwin Vega "Earthquake" speakers are a "small" horn in a "large" ported box and it's rated down to 45Hz.

Most pro subwoofers used live and in dance clubs are "tuned" to go down to around 40Hz. That's close to the lowest note on a standard bass guitar and it's low enough for bass you can feel in your body (if the bass is strong enough). If you go lower you tend to lose efficiency so you need more-bigger woofers and more-bigger amplifiers. 40Hz is a good compromise for filling a large venue with bass everybody can feel. For home use, or in studios, you don't need the efficiency and you can more easily go lower.
 
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voodooless

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the horn looks too small to be effective for bass.
Yes, but that is also not the point. The point is to create a point source with a very wide bandwidth ;) Depending on the horn size you’ll also get pattern control for a very wide bandwidth.

If you also want a bass horn to go along with the synergy, make something like this:


.. but it won’t be a 2-way anymore.
 
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