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Old 15th March 2011, 02:15 PM   #671
jbell is offline jbell  United States
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Quote:
Originally Posted by salzburgsoundsystem View Post
P.S. JBell - you were right, lying on their sides on the floor with bottoms touching is excellent! Seriously outperformed the first time when they were plit and upright, despite being much further from walls than before!

The promoter said he finally understood why the damn things (stadium horns) were so big and heavy!

ALLLLRIGHT !!! Glad you had a success. I always enjoy hearing about success.
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Old 15th March 2011, 04:15 PM   #672
Djim is offline Djim  Netherlands
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Quote:
Originally Posted by salzburgsoundsystem View Post
This would make for a very fast and easy build! Much appreciated by those of us with limited tools / skills.
I believe symmetrical designs are way easier to build. I did the same for the THAM and it worked. We build our cabs under pressure (ton/cm2) and then 90 degrees connections are way easier to setup.

Quote:
Originally Posted by jbell View Post
Not sure what you mean by no 2x90 degree bends??
When two 90 degrees bends face each other, for instance like in your cube model. That ‘style’ is non-gentle bending. Always try to go for S bends. I’ll show the 180 degree bends (look at their centre point). Corners a,b and c are 90 degrees (although bend c is actually not).
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Old 15th March 2011, 04:44 PM   #673
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If you wanna have it more radical, this one has no 2x 90 bends facing, last bend is almost 180 degrees and you have a little more control over the last expansion. Only needs one bracing stud for the bottom panel since all other outside panels have bracing. As you can see haven't worked it out and no idea if it fits the one sheet challenge.
I like this one but the path length seems to be shorter than the SS15. Andy
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Old 15th March 2011, 05:29 PM   #674
Djim is offline Djim  Netherlands
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Originally Posted by tb46 View Post
Post #664: "...path length extension..." (Djim’s Mod1)
- Does not work with this driver, yours kills the region from ~~130-210Hz, does not add much below 45Hz, and looses output from ~~50Hz-80Hz. As you are indicating, with this type of construction you are back to build-test-modify, and guess again. What seems to help consistently with this driver is to reduce the L12 distance, and/or reduce S1, or couple the driver as closely as possible to the throat (S2).
Oliver, the extra cavity is supposed to be filled with acoustic materials. Dense enough so NO frequencies above 100Hz will see the extension. So for >100Hz it’s the same path only with a squeezed end. And yes that techniques works. This technique is exactly what you use in acoustic treatment for studio’s. The slightly rotated driver panel works and JBell already used it with success, I believe.

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Originally Posted by tb46 View Post
I don't know if soho54 could model something like the ones in #664/665/666 in AkAbak. I did a complete fold similar to #666 to find room for a chamber to house Helmholtz resonators close to the throat, but again, that would belong into a different thread
The idea is not to use the cavity as a Helmholtz resonator. Again the filling must be dense enough to let low frequency trough and higher frequencies not. I think you are missing the concept here. I don’t know if Akabak can be predicting such thing.

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Originally Posted by tb46 View Post
Keep on trying, I'll try to fire up AkAbak for the SS15, but I don't have any hope for extending the low end response within the parameters of the project.
Like I said before, I never had the intention to extend the low end. Maybe a little extra 47Hz (that runs out to 40Hz) and hopefully not to much at cost of 90hz…

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Originally Posted by tb46 View Post
Attached is a quick try at your modifications (driver board/throat extension) in Hornresp.
Could you share your txt file from your HornResp?

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Originally Posted by 4pyros View Post
I like this one but the path length seems to be shorter than the SS15. Andy
Andy, the length sits in the bends. It’s just a quick schematic drawing, not very accurate. The strengths of this design sits in the constant changing of the airwaves. So there is no long path where ˝ wave cancellations or long turbulances can develop. Also the 180 “S” folds make sure that each time the other side of the bend changes the air mass. Another interesting thing is the many corners which can help in finding the right spots for problem areas within the band pass.

Last edited by Djim; 15th March 2011 at 05:34 PM.
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Old 15th March 2011, 08:32 PM   #675
Djim is offline Djim  Netherlands
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Oliver, if you are that worried about the upperband then paint the last piece you put in (with a primer for instance, make sure it doesn't 'eat' the foam). Painted side towards the cone of course...

This will ad a reflective film on the surface.
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Old 15th March 2011, 09:09 PM   #676
tb46 is offline tb46  United States
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Hi Djim,

Interesting suggestions. I'm looking for something that produces results in Hornresp or in AkAbak at a basic level. I would have a hard time to simulate a corner packing with, e.g.: latex paint seal cover. Anyway, always interesting, keep 'em coming.

I'm attaching another SPL window, and the .txt files for Hornresp.

Regards,
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File Type: jpg Djim_throat_baffle_mods_2011_Mar15_2.jpg (32.0 KB, 362 views)
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File Type: txt djim_1.txt (481 Bytes, 20 views)
File Type: txt djim_2.txt (481 Bytes, 15 views)
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Old 16th March 2011, 08:46 PM   #677
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Reading this tread with most interest indeed. But I have a question, how high can you cross this sub, if you push it? I read earlier a couple 40 pages back that Jbell mentioned something about "sounding good up to 200hz and maybe 250hz". Have anybody played them that high and how does it sound?

I have this tops that highpass at 250hz. It would be such a neat system...

Thanks in advance!
/Anders
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Old 16th March 2011, 11:14 PM   #678
jbell is offline jbell  United States
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Originally Posted by Brytnardz View Post
Reading this tread with most interest indeed. But I have a question, how high can you cross this sub, if you push it? I read earlier a couple 40 pages back that Jbell mentioned something about "sounding good up to 200hz and maybe 250hz". Have anybody played them that high and how does it sound?

I have this tops that highpass at 250hz. It would be such a neat system...

Thanks in advance!
/Anders

While I've only personally listened to every 1hz sine waves up through 200hz, I've tested up through 250hz with nothing ugly sounding. As long as your tops are above subs, so there isn't any midbass localization from 100-250, I see no reason at all why this wouldn't work for you.

Click the image to open in full size.
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Old 17th March 2011, 12:25 AM   #679
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Originally Posted by jbell View Post
While I've only personally listened to every 1hz sine waves up through 200hz, I've tested up through 250hz with nothing ugly sounding. As long as your tops are above subs, so there isn't any midbass localization from 100-250, I see no reason at all why this wouldn't work for you.

Click the image to open in full size.
I see two possible problems with crossing a SS15, (or any TH with a FB 50 Hz or lower) at 200 to 250 Hz .

The TH may be a lot tighter pattern than the midbass above it at 250 Hz, systems always sound better when dispersion patterns match at the crossover point.
My Keystone TH is about 90 degree dispersion at 125Hz (6dB down point), it probably is only 45 degrees at 250. I'd expect the SS15 may even be more narrow that high, considering the mouth shape differences between the two cabinets.
It would take a huge,very long mid horn to have 45 degree pattern control at 250 Hz.

Problem two may be a difficulty in matching phase at the high crossover point, IIRC the SS15 phase is going through a big phase swing that high. Matching the phase (using delay) at 250 Hz will result in a rapid phase change below the crossover point, which sounds unnatural.

Jim, have you ever posted the phase response of the SS15 ?

Does it match the simulation ?

Art

Last edited by weltersys; 17th March 2011 at 12:30 AM.
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Old 17th March 2011, 01:27 AM   #680
jbell is offline jbell  United States
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I'm not sure what you recall for the phase swing for the ss15 in the 200-250 range.
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