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Old 21st October 2011, 03:30 PM   #1
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Default Help with Rear Loaded Horn Design

Hello, I could use some help and advice on a rear loaded horn for the B&C 12PE32 driver. I am using Hornresp, and what I did was to use it for designing a hyp-ex horn in 1Pi space with the intention of folding it up and putting it into 0.5Pi space (in a corner). It is a 100Hz horn and I need it to go up to 500Hz. I've attached the input screen. In my limited research, I have found that according to this website:
Horn Theory
the throat chamber should be fairly large. He calls it a "coupling chamber", but it looks like a throat chamber to me. I found that in Hornresp the response gets better with really large throat chambers for rear loaded horns. The combined response doesn't look too good unless the path difference is large, like over 50cm. What kind of practical path difference should I choose? Anyone have advice on designing rear loaded horns?
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File Type: jpg 12PE32 rear horn input.JPG (58.7 KB, 244 views)
File Type: jpg 12PE32 rear horn combined response.JPG (45.7 KB, 236 views)
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Old 21st October 2011, 03:35 PM   #2
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The impulse response looks horrible though.... What to do?
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File Type: jpg 12PE32 rear horn impulse response.JPG (32.8 KB, 235 views)
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Old 21st October 2011, 04:21 PM   #3
Helmuth is offline Helmuth  Netherlands
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Quote:
Originally Posted by dirkwright View Post
The impulse response looks horrible though.... What to do?
Make a frontloaded horn like klipsch la scala. See my avatar

See this topic.
Back Loaded Horns
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Last edited by Helmuth; 21st October 2011 at 04:28 PM.
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Old 21st October 2011, 04:48 PM   #4
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Quote:
Originally Posted by Helmuth View Post
Make a frontloaded horn like klipsch la scala. See my avatar

See this topic.
Back Loaded Horns
OK, have you found the La Scala style of horn to extend up to about 500Hz? I gave up on that when it was pointed out to me that it probably wouldn't, and that the folds would introduce a lot of dips and peaks in the SPL response curve. I suppose of course that a rear folded horn would also have a lot of irregularities in the response.

Have you designed La Scala type horns for other drivers?
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Old 21st October 2011, 05:02 PM   #5
Helmuth is offline Helmuth  Netherlands
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Quote:
Originally Posted by dirkwright View Post
OK, have you found the La Scala style of horn to extend up to about 500Hz? I gave up on that when it was pointed out to me that it probably wouldn't, and that the folds would introduce a lot of dips and peaks in the SPL response curve. I suppose of course that a rear folded horn would also have a lot of irregularities in the response.

Have you designed La Scala type horns for other drivers?
I build a huge backloaded horn in 2010. The crossover around 200-400Hz from hornmouth to drivercone gave interference distortion what with to poor subbas was making me quit backloaded horn's. Project presentation Horn Almighty
I see this as a repeating problem for backloaded horns.

Better have a softer suspension driver that hornmouth response above 100-150Hz. So the 300Hz area stays smoother.

I made a small backloaded horn for my colleague who is still very pleased with it it uses a visaton w130s I designed a two way active loud speaker. It sounds remarkably deep for a horn and it is very tight for metal bass he plays often. It is not high efficient but still very loud played on volume with such a small driver.
http://www.visaton.de/en/chassis_zub...n/w130s_8.html


The front loaded sm115 is beautiful because the horn cutoff above 500Hz also cuts of second and third harmonic above 500Hz
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Last edited by Helmuth; 21st October 2011 at 05:16 PM.
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Old 21st October 2011, 05:17 PM   #6
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I agree with Helmuth - make a front horn. However I'd suggest making a straight horn. The likelihood of it working well will increase dramatically. For example, something like this:
Midbass Horns
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Old 21st October 2011, 05:29 PM   #7
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Originally Posted by John Sheerin View Post
I agree with Helmuth - make a front horn. However I'd suggest making a straight horn. The likelihood of it working well will increase dramatically. For example, something like this:
Midbass Horns
Well, I had a long discussion in the Hornresp thread about his spreadsheet for designing tractrix horns. The upshot was that volvotreter's spreadsheet was incorrect for tractrix horns. His spreadsheet is fine for hyp-ex ones though.

A 100 Hz hyp-ex for this driver in 1/2 space is I think about a meter long, not including the back chamber.
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Old 21st October 2011, 05:32 PM   #8
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Originally Posted by Helmuth View Post
I

The front loaded sm115 is beautiful because the horn cutoff above 500Hz also cuts of second and third harmonic above 500Hz
OK, so back loaded horns are basically impossible to get right....

What is this "sm115" horn?

edit: never mind. The Beyma sm115 I assume is what you're talking about.

Last edited by dirkwright; 21st October 2011 at 05:36 PM.
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Old 21st October 2011, 05:36 PM   #9
Helmuth is offline Helmuth  Netherlands
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OK, so back loaded horns are basically impossible to get right....
It is a way to have a more efficient loudspeaker not a way to get more high-ended sound. The horn loading helps to control the woofer movement.

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What is this "sm115" horn?
beyma sm115
Back Loaded Horns
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Last edited by Helmuth; 21st October 2011 at 05:38 PM.
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Old 21st October 2011, 05:54 PM   #10
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OK, so back to the front La Scala horn. Do you have any suggestions on how to fold up a straight horn to make it fit in the La Scala style enclosure? Also, I was told that a La Scala style horn with the parallel top and bottom boards would sound bad at the higher frequencies.
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