TH-18 Flat to 35hz! (Xoc1's design) - Page 73 - diyAudio
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Old 24th August 2012, 05:26 PM   #721
kctess5 is offline kctess5  United States
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Quote:
Lol, the Cyclops is a year older, a proven concept and build many times (probably more than Xoc1-TH18's). That it is less known on DIY is another matter. If you google more smart you can find out that the Cyclops is especially appreciated for large outdoor events. Actually, that was the original goal of the designer.
My bad...

Quote:
But you are right about the downsides, it costs more to build, it is larger, needs two people to move around and has less low frequency extension compared to an optimised Xoc1-TH18 (and it is not optimised yet).
Considering that, especially that I would need two people to move it around, I might go with the TH-18. It seems like even though it will weigh about 150 lbs, with the driver near the bottom tilting and rolling it shouldn't be all that difficult for one person.

One more expense to consider for the cyclops is the larger grill area needed as opposed to the th-18 with the smaller mouth. From what I've seen the expanded metal needed can actually be quite expensive. I could be off base here but it also looks like the th-18 would be better protected from rain
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Old 24th August 2012, 05:48 PM   #722
kctess5 is offline kctess5  United States
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Looking at the cyclops it seems like it could benefit quite a lot from v coupling, thoughts?
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Old 24th August 2012, 07:37 PM   #723
Djim is offline Djim  Netherlands
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Hi Tom,

Sorry Tom, I should have left out your name. My intentions were only to generalise the old fold-style and not how you use it.

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Originally Posted by Tom Danley View Post
Also considering the wavelengths involved, would be hard to find an acoustic reason for improved phase response and actually one can’t make that assertion based on measurement unless one has built an identical horn but laid out differently.
Many DIY designs of horns and tapped horns with a similar backwards rolled fold-style end up in a distance between the centre of the driver and the true beginning of the horn. Sometimes this is wanted but usually it is the result of errors in translating the model into an actual drawing. The distance between the driver and the true beginning of the horn has its influence on the phase response. You seem to have managed to find a solution which almost separates the horn and compliance volume above the centre of the driver. Correct me if I am wrong but it looks like there were times you had a different approach …

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Originally Posted by Tom Danley View Post
They reminded me of the failures when I was working out the Servodrive subwoofers. Those could fold the cone into a sort of a star shape and produce creases that ran from the center to the outer edge. To get a better feel for what was going on then, we made a Plexiglass window and found at a specific frequency, one could fold up the cones on command at that “just right” frequency (very disheartening at the time). The solution was to make a very strong cone, one a 300 LB could stand on and not collapse.

Last edited by Djim; 24th August 2012 at 07:43 PM.
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Old 25th August 2012, 08:49 PM   #724
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Quote:
Originally Posted by Djim View Post
Many DIY designs of horns and tapped horns with a similar backwards rolled fold-style end up in a distance between the centre of the driver and the true beginning of the horn. Sometimes this is wanted but usually it is the result of errors in translating the model into an actual drawing. The distance between the driver and the true beginning of the horn has its influence on the phase response. You seem to have managed to find a solution which almost separates the horn and compliance volume above the centre of the driver. Correct me if I am wrong but it looks like there were times you had a different approach
Can you please show an example of this situation?
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Old 25th August 2012, 09:01 PM   #725
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Quote:
Originally Posted by Djim View Post
Many DIY designs of horns and tapped horns with a similar backwards rolled fold-style end up in a distance between the centre of the driver and the true beginning of the horn. Sometimes this is wanted but usually it is the result of errors in translating the model into an actual drawing. The distance between the driver and the true beginning of the horn has its influence on the phase response. You seem to have managed to find a solution which almost separates the horn and compliance volume above the centre of the driver. Correct me if I am wrong but it looks like there were times you had a different approach
Can you please show an example of this situation?
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Old 26th August 2012, 03:51 AM   #726
Djim is offline Djim  Netherlands
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Originally Posted by BP1Fanatic View Post
Can you please show an example of this situation?
You were there

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Excellent illustration! The 1st pic looks like the CB's people are building on speakerplans.com.
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Old 29th August 2012, 11:52 AM   #727
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Originally Posted by kctess5 View Post
It seems like even though it will weigh about 150 lbs, with the driver near the bottom tilting and rolling it shouldn't be all that difficult for one person.
It isn't *difficult* for one person, but is *is* front heavy. You've got to tilt it WAY back to get it on it's balance point. WAY back (and I'm using neo drivers).
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Old 29th August 2012, 01:31 PM   #728
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Realized I haven't posted pictures of my TH-18s I've been using for a few months now. I went with the B&C 18SW100 (neo version of the 18TBW100). I used 3/4" baltic birch. My sound partner helped me up through the 3rd picture (1st cab) and I completed the remaining duties, including the 2nd cab. I also added cone make-up/correction (I'll post measurement comparisons later) and a decent sized broomstick brace with circular attachments. They are now finished with one coat of Duratex and are awaiting a few more coats. I also mounted some very nice (and affordable) casters with precision bearings and they ride very solidly and quietly. I cut handles and the back corner and bottom front. A pair of Speakon connectors are mounted on the back in the center. The driver is mounted with stainless bolts & washers and held snug in place with knife-thread inserts (thanks Don) mounted from the inside of the speaker baffle. Last, before mounting the last side, I filled the empty triangle with insulation (in the can) - this stuff is stickier than PL!

Special thanks go out to Xoc1, Djim, epa, jbell and plenty of others who have helped me throughout this journey. After building a couple folded horns and a couple SS15s, I can finally say I'm happy with the performance of my subs - the TH-18s. Since one TH-18 outperforms a pair of either of the other two and take up less space doing it, the SS15s will be for backup and folded horns will be up for sale.

On to the photos:
Attached Images
File Type: jpg TH-18, cut wood.jpg (541.3 KB, 530 views)
File Type: jpg TH-18, four panels.jpg (874.8 KB, 491 views)
File Type: jpg TH-18, six panels.jpg (529.9 KB, 459 views)
File Type: jpg TH-18, before bottom.jpg (585.2 KB, 419 views)
File Type: jpg TH-18, no braces.jpg (588.0 KB, 406 views)
File Type: jpg TH-18, one brace.jpg (375.2 KB, 179 views)
File Type: jpg TH-18 inside wo driver.jpg (430.8 KB, 197 views)
File Type: jpg TH-18 inside w~driver.jpg (482.8 KB, 263 views)
File Type: jpg TH-18, bare ext, no cone corr.jpg (485.0 KB, 235 views)

Last edited by CRESCENDO; 29th August 2012 at 01:45 PM.
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Old 29th August 2012, 01:51 PM   #729
epa is offline epa  Netherlands
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cheers m8.
wel executed
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one good thing about music ,when it hit you feel no pain.
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Old 29th August 2012, 05:02 PM   #730
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Nice construction!
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