Horn vs. Waveguide

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#321
Jmmlc said:
Hello Earl,

All the simulations I have performed using Hornresp gave pretty accurate results for the "Le Cleac'h flare horns".

If there is something wrong with Hornresp when simulating an oblate spheroidal waveguide then may be you should ask David McBean to verify and modify Hornresp.


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Its the obligation of the software writer to verify his code, not mine. Its clearly wrong.
 
#322
salas said:


So a diffraction horn takes less square inches to go down as far as a WG. Custom coverage patterns are easy using diffraction, but using a WG it is difficult to do that and still be a WG?
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LF effect for horns or waveguides is pretty much irrelavent IMO. I'm not talking about LF effects, I'm talking about directivity control. Diffraction takes less space to get a wide pattern than a waveguide. Its easy to diffract a wave to be wide, but its very difficult to coax it into a spherical shape without diffraction. Its takes length and mouth area to get good control with low diffraction. All this has nothing to do with LF response - waveguides and horns all work about the same at the LF end (contrary to the posted simulations).
 
#323
"The impulse looks funny. Normally the leading edge of the impulse should be going upward. If it goes downward, it's either the mic signal is inverted (as most Panasonic WM61 type mics), or driver related issues (haven't figured this out yet)."

The drivers may have been phased differently depending on the amp used or if I simply goofed up with the polarity when I hooked up the drivers. It's the same driver in the 2307,2344,2370

Rob🙂
 
#324
gedlee said:



How can there be CD without a waveguide? No single source could do this without a waveguide. It can be done with a very large array of small sources, but thats never gained wide acceptance for sound quality.
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Tinitus means compression driver, not constant directivity.

With minimal horns, they are sold as "Arrayable waveguide elements."

http://bmspro.com/4510ND.bms_4510nd0.0.html

Unterminated, they're diffraction devices.

With no horn, the phase plug is the waveguide, uhmm, "horn."

With no phase plug, they're inverted domes on a short transmission line.

Yeah, all that's been measured, of course. We can do it ourselves, if desired....
 
#325
.........they were so they adopted some of my ideas, some more than others (like Peavey who actually copied it outright and patented it).
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So the Peavey Quadratic Throat Waveguide is in fact a waveguide? Albeit based on your ideas?

It has always intrigued me because they had a quite in-depth white paper explaining the faults of horn designs. They do have a foam lining at the edge to minimize diffraction...
 
#326
Variac said:



So the Peavey Quadratic Throat Waveguide is in fact a waveguide? Albeit based on your ideas?

It has always intrigued me because they had a quite in-depth white paper explaining the faults of horn designs. They do have a foam lining at the edge to minimize diffraction...
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Notice the complete lack of mention of my work. I consulted for Peavy on waveguides a few years before they filed that patent. Very tacky IMO.

They simplified the waveguide by using a circular arc from the throat to the conical sides and called it "revolutionary". Its just a simplified OS contour and I posted the two shapes on my web site once showing how they were very similar. However, the OS will still have less diffraction so why not just do it right? Oh, yea, can't patent that!! But the patent that they got was pointless anyways since they blew it in the claims. Anyone can beat their patent by just doing it better - use an OS contour!

Yes, it is a waveguide since it does not use diffraction per-see, but it is not a "good" waveguide because it is sub-optimal.
 
#327
"They do have a foam lining at the edge to minimize diffraction..."

And they are not the first on that count. This should look familiar it's a Urei 801C horn.

Rob🙂
 

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#329
Variac said:
Well, one great thing is that the Peavey horn is very easy for people to build. Since it would be for personal use, the patent doesn't restrict us.
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This is not stricktly true, it is illegal to "build, have built or otherwise assemble" no matter who you are. Its just very difficult to catch you. However, and I know this first hand, if you post how to easily infringe a patent, like you just did, then you could be guilty of "inducing to infringe" which is also a crime. Bose tried to get me on that law.
 
#330
Robh3606 said:
This should look familiar it's a Urei 801C horn.
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Yep! I know those. =) Did Altec ever do that, or was it just the Urei?

Variac said:
I suppose that instead of foam, one could flare the opening edge with a 4" diameter roll?
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It would work, but maybe not in the same way. The idea is to get a smooth impedance transition at the edge. A sharp terminations causes artifacts. Probably form resonance at the mouth, but I'm not sure.

What I am sure of is that I can both hear and measure it.
http://www.diyaudio.com/forums/showthread.php?s=&threadid=103787&highlight=

Foam, roll-overs, towels, edge slots. There are many different ways to do it.
 
#335
gedlee said:



This is not stricktly true, it is illegal to "build, have built or otherwise assemble" no matter who you are. Its just very difficult to catch you. However, and I know this first hand, if you post how to easily infringe a patent, like you just did, then you could be guilty of "inducing to infringe" which is also a crime. Bose tried to get me on that law.
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I would assume reasonable use for educational purposes takes care of that.
 
#340
Earl,

What will look like an OS waveguide giving a true 160Hz LF cut off?

Best regards from Paris, France

Jean-Michel Le Cléac'h


gedlee said:



LF effect for horns or waveguides is pretty much irrelavent IMO. I'm not talking about LF effects, I'm talking about directivity control. Diffraction takes less space to get a wide pattern than a waveguide. Its easy to diffract a wave to be wide, but its very difficult to coax it into a spherical shape without diffraction. Its takes length and mouth area to get good control with low diffraction. All this has nothing to do with LF response - waveguides and horns all work about the same at the LF end (contrary to the posted simulations).
Click to expand...
 
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