Hornresp gives 12dB boost for corner loading. Is that correct? - AVS Forum | Home Theater Discussions And Reviews
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post #1 of 11 Old 03-12-2020, 07:33 AM - Thread Starter
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Question Hornresp gives 12dB boost for corner loading. Is that correct?

I may be getting too nit-picky over details here, but I noticed something that is driving me mad. For most speakers (subs in particular in this case), modeling software like Unibox and WinISD calculate in half space (2 pi). Then, putting it against a wall moves it to quarter space (1 pi), adding 3dB of output over half space, then corner placement is eighth space (1/2 pi) and adds 6dB over half space.

If that is true, then why does hornresp seemingly double the dB increase? Moving from half space to corner adds 12dB to the SPL chart. Is that correct? Are horns different? If they are, can someone ELI5 (Explain Like I'm Five) as to why that is?

I'm trying to compare ported builds against my dual-horn setup and trying to come to terms with the differences Unibox/WinISD are giving me in comparison to Hornresp.

I've searched google and here and could not seem to find an answer. Thanks in advance.
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post #2 of 11 Old 03-12-2020, 09:33 AM
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Quote:
Originally Posted by SilentJ20 View Post
I may be getting too nit-picky over details here, but I noticed something that is driving me mad. For most speakers (subs in particular in this case), modeling software like Unibox and WinISD calculate in half space (2 pi). Then, putting it against a wall moves it to quarter space (1 pi), adding 3dB of output over half space, then corner placement is eighth space (1/2 pi) and adds 6dB over half space.



If that is true, then why does hornresp seemingly double the dB increase? Moving from half space to corner adds 12dB to the SPL chart. Is that correct? Are horns different? If they are, can someone ELI5 (Explain Like I'm Five) as to why that is?



I'm trying to compare ported builds against my dual-horn setup and trying to come to terms with the differences Unibox/WinISD are giving me in comparison to Hornresp.



I've searched google and here and could not seem to find an answer. Thanks in advance.


Never tried the various options, I just model everything in half space. Actual in-room response is so far from models that I don’t bother with trying to guess the outcome of placement. I just compare the half-space response of different designs.

I wouldn’t suggest close comparison between programs anyway. Use the other programs to tweak if you prefer, but compare the final results in hornresp. Takes out the different-program variable.

Chris
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post #3 of 11 Old 03-12-2020, 06:04 PM
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Not sure what you're seeing, but I only see a 6 dB increase when I switch from 2pi to 0.5pi with the default model.
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post #4 of 11 Old 03-12-2020, 09:12 PM - Thread Starter
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Originally Posted by a77cj7 View Post
Never tried the various options, I just model everything in half space. Actual in-room response is so far from models that I don’t bother with trying to guess the outcome of placement. I just compare the half-space response of different designs.

I wouldn’t suggest close comparison between programs anyway. Use the other programs to tweak if you prefer, but compare the final results in hornresp. Takes out the different-program variable.

Chris
That makes sense. It took me long enough to determine that Unibox and WinISD used half-space, so now I at least have a baseline. I wasn't sure if I could trust the output model I was getting. I know it's not worth nit-picking over a couple dB (even 3dB isn't very much) but 6dB starts to become noticeable.

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Originally Posted by lilmike View Post
Not sure what you're seeing, but I only see a 6 dB increase when I switch from 2pi to 0.5pi with the default model.
Huh, odd. I remember double checking everything and the only change I made was the acoustic space and the increase was indeed 12dB. Are there other settings in hornresp I may have messed with that could account for that? I also wasn't sure if maybe that was just one of the qualities of horns, placing them in a corner got more benefit than other types. Oh well. I'll stick with comparing half-space only models for my comparisons.
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post #5 of 11 Old 03-13-2020, 11:26 AM
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Some cabinets do simulate with more of a boost at the low corner. I think that is due to an undersized mouth, but I am not sure. I was looking at the midband changes, and when I changed from 4pi to 0.5pi, I saw clean 3 dB steps for each halving of the radiation angle, exactly what would be expected.

For my work with subs, I simulate things in a 2pi setting, that tends to result in a pretty good match to what I measure in a groundplane environment if I have done a good job simulating and measuring what I built.
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post #6 of 11 Old 03-17-2020, 04:13 PM - Thread Starter
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I've attached the spl curves to show what I'm seeing. The only change from top to bottom was changing from half space to corner space, and it is indeed a 12dB increase.

I'll try and get a pic of the input file later (i mainly use a chromebook, so hornresp is on a different computer)
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post #7 of 11 Old 03-17-2020, 05:10 PM
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"Corner loading" is ambiguous.

On the floor away from walls is one corner; on the floor next to a wall is two corners.

I believe you get +6 dB for each.

Noah
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post #8 of 11 Old 03-17-2020, 05:20 PM
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Trihedral corners can give some big gains. Like, corner corner lol.

- MIRAGE OM-C2 Center, MIRAGE M490 L/R, 4 jbl 8330a surr , 8 x jbl 12" subs w/Inuke 6000. JVC RS420, Denon x4000, Sony x800 -
Classix ii's + building Paul Carmody Sunflower Redux for 2 channel
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post #9 of 11 Old 03-19-2020, 01:05 PM
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Quote:
Originally Posted by SilentJ20 View Post
I've attached the spl curves to show what I'm seeing. The only change from top to bottom was changing from half space to corner space, and it is indeed a 12dB increase.

I'll try and get a pic of the input file later (i mainly use a chromebook, so hornresp is on a different computer)
Interesting. Might be worth discussing over in the HornResp thread at DIYAudio.
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post #10 of 11 Old 03-19-2020, 06:39 PM
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Interesting how it also reduces the ripple amplitude of the resonances >100 Hz by 5 dB.


Quote:
Originally Posted by SilentJ20 View Post
I've attached the spl curves to show what I'm seeing. The only change from top to bottom was changing from half space to corner space, and it is indeed a 12dB increase.

I'll try and get a pic of the input file later (i mainly use a chromebook, so hornresp is on a different computer)

Noah
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post #11 of 11 Old 03-23-2020, 09:18 AM
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If you build, let us know when you verify your plots in real world and compare to the simulation. One problem with any boundary loading simulation is that the boundary(s) can vary in building materials from room to room. If one room is made with 1/4" panelling, it won't have the same affect as a concrete wall and floor of a basement. Then the horn construction can also have losses as a result of it's geometry, folds , braces and building materials.
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