TH-18 Flat to 35hz! (Xoc1's design) - Page 101 - diyAudio
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Old 20th September 2012, 08:27 PM   #1001
tb46 is offline tb46  United States
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Hi again,

And just because it was so much fun, here is a simple cone correction using 1/2" discs (it may be worthwhile to do the math, as every box is different, and every speaker is different too [and your math may be better than mine] :-) ), at least this is one board that doesn't need additional bracing (?):

Regards,
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File Type: pdf simple cone correction_using_discs.pdf (23.4 KB, 208 views)
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Old 20th September 2012, 10:43 PM   #1002
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Hi Oliver,
Interesting ,so do you think in the case of using a 18 " speaker that the disks would react differently as apposed to the stub that goes across the whole camber or if the stub was shorter what difference in responce would that have,
To all of you guys Nice work on cone corrections ,I am beginning to figure it out ,Got REW setup and working just got to get the hows and whys to correctly figured, to hopefully have a correct response curve,!
Have A GREAT Day!
ns
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Old 21st September 2012, 02:10 AM   #1003
tb46 is offline tb46  United States
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Hi noSmoking,

Post #1002: "...do you think in the case of using a 18 " speaker that the disks would react differently as apposed to the stub that goes across the whole camber or if the stub was shorter what difference in responce would that have..."

If you are refering to the examples I posted in Posts #997 and 1001, I think that the results would be quite similar; they are both examples of "simple cone correction".

What Sergey (grec13) indicated in Post #992, and Art (weltersys) pointed out in Post #996 is that there is a difference between what could be called a "V" throat and simple cone correction. Art already gave the reference to Post #528, in Post #546 Djim shows the basic cone volume corrections for both driver sides (you are really looking at correcting volumes as Djim has by now amply demonstrated), then in Post #562 Martin (Xoc1) shows a basic outline for updating the TH18 (and cross-references to the other thread), and it goes on and on, sadly the picture Djim posted in #841 has been removed, but the following discussion pretty much clarifies what is going on, and how important the design integration between driver and enclosure has become in the tapped horn. Anyway, I'm rambling, this is really a remarkable thread, and it's so worth reading carefully. Your measurements of your enclosure with the throat treatment from Post #938 should add to the data, just guessing I would say that you are somewhere between simple cone correction and "V" throat.

Regards,
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Old 21st September 2012, 05:42 AM   #1004
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Hi Oliver,
Well put, I have studied and read all those threads and other info ,I now have a very good Idea of horn corrections to implement in to the camber now,I will do some tests and see what I can get them to do,LOL.
Thanks all of you for your time and help!
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Old 21st September 2012, 07:52 AM   #1005
grec13 is offline grec13  United States
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Default Oliver, thank you for clarification.

Quote:
Originally Posted by tb46 View Post
Hi noSmoking,

Post #1002: "...do you think in the case of using a 18 " speaker that the disks would react differently as apposed to the stub that goes across the whole camber or if the stub was shorter what difference in responce would that have..."

If you are refering to the examples I posted in Posts #997 and 1001, I think that the results would be quite similar; they are both examples of "simple cone correction".

What Sergey (grec13) indicated in Post #992, and Art (weltersys) pointed out in Post #996 is that there is a difference between what could be called a "V" throat and simple cone correction. Art already gave the reference to Post #528, in Post #546 Djim shows the basic cone volume corrections for both driver sides (you are really looking at correcting volumes as Djim has by now amply demonstrated), then in Post #562 Martin (Xoc1) shows a basic outline for updating the TH18 (and cross-references to the other thread), and it goes on and on, sadly the picture Djim posted in #841 has been removed, but the following discussion pretty much clarifies what is going on, and how important the design integration between driver and enclosure has become in the tapped horn. Anyway, I'm rambling, this is really a remarkable thread, and it's so worth reading carefully. Your measurements of your enclosure with the throat treatment from Post #938 should add to the data, just guessing I would say that you are somewhere between simple cone correction and "V" throat.

Regards,
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Old 21st September 2012, 09:53 AM   #1006
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Hi All

First post here and I'd like to start by just saying thanks to all for the contributions to this thread. Its been a fascinating progression to read and has almost convinced me to give the build a try with the latest "Xoc1" V throat additions.

I have three questions which Id greatly appreciate a response too:
1. Xoc1 are you planning on updating the original drawings to take "V throat" cone correction into account you illustrated in #990? I don't want to land up cutting and gluing only to find an updated cut sheet is on its way.
2.Is the Beyma 18SW1600ND a suitable driver for this design? http://profesional.beyma.com/pdf/18SW1600NdE.pdf Its the only drive I can source locally with similar specs to the B&C 18SW115.
3. Would 2 x TH18 loaded with the above Beyma driver powered by 1800 watt 4ohms/ch provide more output than 4 x SRX718 powered by the same amp? I have 2 x SRX718's and was about to buy a further two but I can pretty much build the TH18's for the price of two new 718's. The sensitivity of the JBL 2268HPL drive is rather poor though (95db) so I expect the Beyma driver (97db) to be a touch louder regardless of the Tapped Horn benefits.

Thanks again for this amazing thread!!
Getting quite excited to give this build a try and will be sure to post pictures of the build phases.
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Old 21st September 2012, 02:46 PM   #1007
djlivex is offline djlivex  United States
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I also have read this project and would like to use the Faital Pro 18" woofer can anyone recommend a neo 18" Faital for this project? Thanks!
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Old 21st September 2012, 07:39 PM   #1008
NEO Dan is offline NEO Dan  United States
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Default ARE WE THERE YET???

Click the image to open in full size.

NOPE, the cook is still cooking.
Wait patiently for the final plans to be done.

Quote:
Originally Posted by PsyCrank View Post
Hi All

First post here and I'd like to start by just saying thanks to all for the contributions to this thread. Its been a fascinating progression to read and has almost convinced me to give the build a try with the latest "Xoc1" V throat additions.

I have three questions which Id greatly appreciate a response too:
1. Xoc1 are you planning on updating the original drawings to take "V throat" cone correction into account you illustrated in #990? I don't want to land up cutting and gluing only to find an updated cut sheet is on its way.
2.Is the Beyma 18SW1600ND a suitable driver for this design? http://profesional.beyma.com/pdf/18SW1600NdE.pdf Its the only drive I can source locally with similar specs to the B&C 18SW115.
3. Would 2 x TH18 loaded with the above Beyma driver powered by 1800 watt 4ohms/ch provide more output than 4 x SRX718 powered by the same amp? I have 2 x SRX718's and was about to buy a further two but I can pretty much build the TH18's for the price of two new 718's. The sensitivity of the JBL 2268HPL drive is rather poor though (95db) so I expect the Beyma driver (97db) to be a touch louder regardless of the Tapped Horn benefits.

Thanks again for this amazing thread!!
Getting quite excited to give this build a try and will be sure to post pictures of the build phases.
The Byema will work and the 2268H from the SRX718 will also work if the compression is lowered, S2=~600.

Quote:
Originally Posted by djlivex View Post
I also have read this project and would like to use the Faital Pro 18" woofer can anyone recommend a neo 18" Faital for this project? Thanks!
I have tried the 15HP1030 on an adapter plate, it works fine up to 1kw.
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Old 21st September 2012, 10:41 PM   #1009
NEO Dan is offline NEO Dan  United States
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Quote:
Originally Posted by NEO Dan View Post
The Byema will work and the 2268H from the SRX718 will also work if the compression is lowered, S2=~600.
Thinking about this, just build with the plans in the first post and load the 2268H. That should work out just fine.
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Old 22nd September 2012, 01:18 AM   #1010
Xoc1 is offline Xoc1  United Kingdom
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Default Is this any good?

Maybe I need to sleep. I'm a bit concerned about the 110Hz dip to 96db
BTW this is still with the Precision devices PD1850.
Hopefully I haven't made any errors. Its close to the Hornresp response.
This version is slightly bigger by an inch front to back -
Think that's enough for today
Graph attached and text file for the akabak users to play with.
Regards
Martin (Xoc1)
Attached Images
File Type: jpg TH18MK1-R1.jpg (47.8 KB, 659 views)
File Type: jpg TH18MK1 Prelim.jpg (65.7 KB, 654 views)
Attached Files
File Type: txt TH18mk1 Akabak.txt (3.9 KB, 42 views)
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