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TH-18  Flat to 35hz!  (Xoc1's design)
TH-18  Flat to 35hz!  (Xoc1's design)
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Old 15th September 2012, 02:21 AM   #921
Djim is offline Djim  Netherlands
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Click the image to open in full size.

This is for 'regular' drivers. For drivers with extreme Xvar and Xlim and high Bl, the "V" shape needs to be lowered even further... If you would do that for 'regular' drivers they will run into their dynamic compression too soon. So my suggestion is to make two drawings for each type of driver or go for an in between solution with an attachable piece on top of the "V" for the strongest drivers...

Last edited by Djim; 15th September 2012 at 02:32 AM.
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Old 15th September 2012, 03:58 AM   #922
kctess5 is offline kctess5  United States
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Quote:
Originally Posted by Djim View Post
Follow up for post#917

In order to compensate for the changing cone volume as result of excursion (towards S4) you increase the compression factor at S2 by lowering the "stub" or "V".


In order to compensate for the increasing 'overall' compression when the cone moves into the other direction, you need to decrease the compression by making the base of the "stub" or "V" smaller.


Click the image to open in full size.

(see my ealier post on 'ideal' models)
So just wondering... What are you basing all of this on? Is it from a computer simulation or just an educated guess? Not trying to argue im just curious.

For drivers with relatively low xmax, like the 18ps76 (8mm?) Does one have to worry about changing volume with excursion as much? The cross sectional area will only change ny about 10% with full excursion, which seems to be an acceptable tolerance.
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Old 15th September 2012, 05:03 AM   #923
CRESCENDO is offline CRESCENDO  United States
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TH-18  Flat to 35hz!  (Xoc1's design)
Quote:
Originally Posted by noSmoking View Post
Hi Cresendo,
I have been looking and learning about building X0's Th-18 and understand you have a layout for cone correction,I will be using B&C 18PZB100 and was wondering if you would be so kind as to share your finding and how I should change the cut list as this is new ground,I do ok following a design but not well at doing my own but I am getting more informed from the infomation here at DIYAUDIO !
So Thanks in advance,
NS
Sorry, missed this post..

I added my cone correction to his original plan. Mount the baffle cut-out on the panel the driver faces, centered with the driver (use a right angle or T-square to find the center on the opposing panel). Then, measure & calculate how much volume the 18PZB100 has. I screwed and glued strips of wood on top of the baffle cut-out (also centered) to make up my preferred cone volume amount (try somewhere between half the cone's volume and up - I went with half and had nice results). I'll be able to take a picture of what mine looks like pretty soon.
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Old 15th September 2012, 05:11 AM   #924
CRESCENDO is offline CRESCENDO  United States
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TH-18  Flat to 35hz!  (Xoc1's design)
Quote:
Originally Posted by NEO Dan View Post
For SPL testing get the "Goodies" and use REW's metering function. The siginal you want is in:~Keele - Tone Burst Testing Files/Composite Octave Bass Bursts
"Sorry, we are unable to retrieve this document."
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Old 15th September 2012, 05:41 AM   #925
CRESCENDO is offline CRESCENDO  United States
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TH-18  Flat to 35hz!  (Xoc1's design)
Hey NEO Dan,

I've got everything ready to do some REW measurements, but REW is trying to measure & calibrate with my laptop mic :/ I've got "AudioFire4 (3363)" selected in the 1st drop-down under "Input Device and Input". The second drop-down only gives the option of "Default Input". Am I missing something?
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Old 15th September 2012, 06:32 AM   #926
NEO Dan is offline NEO Dan  United States
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Quote:
Originally Posted by Xoc1 View Post
Hi All
The Tour of Britain Cycle Race comes to our town tomorrow, and a I have a gig in town so I have been busy rebuilding and configuring my PA rig.
Don't forget your camera
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Dan
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Old 15th September 2012, 06:34 AM   #927
NEO Dan is offline NEO Dan  United States
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Quote:
Originally Posted by CRESCENDO View Post
Hey NEO Dan,

I've got everything ready to do some REW measurements, but REW is trying to measure & calibrate with my laptop mic :/ I've got "AudioFire4 (3363)" selected in the 1st drop-down under "Input Device and Input". The second drop-down only gives the option of "Default Input". Am I missing something?
Go to sound preferences and set the IO devices on the Mac to your external sound card then restart REW...

edit: I meant Mac system preferences > sound preferences... Then the external sound device can be selected so you can use the default device in REW settings...
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Dan

Last edited by NEO Dan; 15th September 2012 at 07:01 AM.
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Old 15th September 2012, 06:41 AM   #928
noSmoking is offline noSmoking  United States
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TH-18  Flat to 35hz!  (Xoc1's design)
Hi Crescendo,
I have one cabinet all most completed ,Have you posted your build ? I would like to see it and read your info,I am a newbie at testing and adjusting speakers,but I get a lot of help here and it's appreciated!
I will finish the cabinet tomorrow and start with the test set up ,first time so I might be a while till I get it figured out,lol.
NS
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Old 15th September 2012, 06:44 AM   #929
NEO Dan is offline NEO Dan  United States
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Originally Posted by CRESCENDO View Post
"Sorry, we are unable to retrieve this document."
bummer. I'll PM you in a couple...
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Dan
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Old 15th September 2012, 06:49 AM   #930
noSmoking is offline noSmoking  United States
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TH-18  Flat to 35hz!  (Xoc1's design)
Default here's some more Pics

Hi,
I added some reflectors and the cone corrector spec by Djim and Martin,It was a pain cutting these angles but I drew them full scale and marked the wood and sawed them out ,took some time but Testing will tell,lol.All is glued and screwed ,I'll finish tomorrow,and give it a day to dry,Then it gets the juice,lol.
NS
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