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Old 9th August 2010, 11:17 AM   #21
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"Thomas Danley said there was no advantage to a Tapped Horn once it got to the size of a full horn."

A full LAB 12 horn is eight boxes in 4Pi.
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Old 9th August 2010, 11:39 AM   #22
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Quote:
Originally Posted by djk View Post
"Thomas Danley said there was no advantage to a Tapped Horn once it got to the size of a full horn."

A full LAB 12 horn is eight boxes in 4Pi.
I thought he showed 6boxes in 2Pi space and 12boxes flying in 4Pi space.

That comes down to 3boxes in Pi space, i.e. up against a wall and sitting on the floor. That's a mighty big speaker ~1.8cub metre (45inch * 45inch * 67.5inch = 79cub feet)
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Old 9th August 2010, 11:47 AM   #23
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"I thought he showed 6boxes in 2Pi space and 12boxes flying in 4Pi space."

You could very well be right, in any event it is a very large bulk.

For a single or stacked pair of LAB 12, a TH of similar bulk will eat the LAB 12's lunch.

Click the image to open in full size.
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Last edited by djk; 9th August 2010 at 11:50 AM.
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Old 9th August 2010, 11:55 AM   #24
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your comparison agrees with Danley's statement.
The TH is competitive (or louder) when the speakers are smaller than a full horn.
In your comparison of 2 boxes on the floor (2Pi space), we are looking at 1/3 volume of the full horn for this loading.
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Old 9th August 2010, 02:29 PM   #25
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Tried the WayBack machine and found Peter Sylvester's website:

http://web.archive.org/web/*/http://...t.net/~labhorn
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Old 9th August 2010, 04:48 PM   #26
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Found Brad Litz's stuff using the WayBack machine:

Internet Archive Wayback Machine

Brad did a great job but it did get a little more complicated!
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Old 9th August 2010, 05:05 PM   #27
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The throat module got REALLY complicated. Thank Heaven for pocket screws! Instead of two compound cut pieces,
he ended up with six!
Attached Images
File Type: jpg Brads.jpg (66.1 KB, 299 views)
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Last edited by Don Snyder; 9th August 2010 at 05:12 PM.
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Old 13th August 2010, 05:08 AM   #28
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Over the last couple of days I've been trying to get a more accurate simulation of the Labhorn by including the offset drivers and breaking the horn into actual segments instead of the previous method of just simulating a hyperbolic flare with 0.5 T.

The first problem is that Danley's specified horn (the design before he folded it) doesn't fit inside a Labhorn sized box. The next problem, as someone else mentioned previously, is that the Labhorn is pretty weird in it's first couple of feet (starting with a throat that's too big, then contracting until it's too small, then expanding again at a rate that quickly makes it too big again, etc, etc.). The third problem - the big one - is that I can't "fix" the Labhorn. There's no room. There's no way I can make the back chambers big enough without changing other parts of the horn for the worse. A full redesign of the folding in a larger overall package would do it, but that's not something I'm really interested in right now.

My next step is to do a complicated but accurate model with Akabak to try to find out what Danley was thinking when he folded it. Maybe there's a couple of folding secrets to be learned here or maybe he just got lazy and didn't do a particularly good job with the fold. The Akabak model won't happen anytime really soon.

As I mentioned previously, I don't care for the v.2 or v.3 options. The v.2 is quite similar to the original and the v.3 makes some changes I'm not comfortable with - and he didn't end up building what he modelled anyway. The v.3 throat comes to a point, so his compression ratio is a lot larger than he thinks (IIRC he stated it was 3:1, and he incorrectly modelled the horn throat as part of the front chambers). That alone isn't necessarily a huge problem, but it doesn't give me any confidence that he knew what he was doing. And the complexity of the v.3 is ridiculous.


In the meantime, I'm also looking into different drivers to use in a Labhorn size box. Mainly looking into single 15 inch drivers like the Eminence 3015. The single 15 won't go quite as loud but a much flatter response is possible and driver cost is cut almost in half.

Last edited by just a guy; 13th August 2010 at 05:22 AM.
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Old 13th August 2010, 04:39 PM   #29
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Default Just a guy: Simulation is always a compromise.

The proof of the labhorn is that it works. Compromises in the flare rate have little effect on the bottom two octaves, where the labhorn is used.
Brad Litz's (v.3) front chamber is a complex volume that is defined more by the driver's front volumes than the taper of the baffle. The chamber would be better modeled as a soccer ball than a wedge.

I'm sorry I wasted your time, finding the materials you asked for.
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Old 13th August 2010, 05:12 PM   #30
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First and foremost this:

Quote:
Originally Posted by Don Snyder View Post
I'm sorry I wasted your time, finding the materials you asked for.
I truly appreciate the effort Don, but if you check post #17 I found that stuff almost a week ago and briefly commented on it.

Quote:
The proof of the labhorn is that it works.
Yes, and it works well. But measurements and simulations and real world thermal overload testimonials show it could work better. It might take a bigger box but it could work better.

Quote:
Compromises in the flare rate have little effect on the bottom two octaves, where the labhorn is used.
Actually, changing the flare rate has a pretty profound effect. I can show you general simulations if you want but I don't have a complex model of the Labhorn worked up yet.

Quote:
Brad Litz's (v.3) front chamber is a complex volume that is defined more by the driver's front volumes than the taper of the baffle. The chamber would be better modeled as a soccer ball than a wedge.
I haven't spent any time trying to model this version. There are several reasons I don't like it much, I just don't like the choices he made.

Last edited by just a guy; 13th August 2010 at 05:15 PM.
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