TH-18 Flat to 35hz! (Xoc1's design) - Page 145 - diyAudio
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Old 19th September 2013, 04:08 AM   #1441
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Quote:
Originally Posted by xrk971 View Post
Xoc1,
Thanks for pointing me to the post by TundraLTD (nice work there Tundra!). Tundra's model uses 'duct' elements, which I do not believe account for the physical effects of the various folds and turns (which act as inherent fluidic low pass filters). I plan to model the turns as expansions/contractions with a 'waveguide' element where I will include the inertia effect of turns using 'Acoumass', and damping using 'Acouresistance'.
Regards,
X
Well I'd call myself an Akabak novice at best. In the messages I sent back-n-forth with Mr Danley he recommended keeping the models simple, building and measuring as the models tend to produce things that aren't measured in the real world. The model in the link is overcomplicated, the simplified model shows nearly the exact same plot
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Old 19th September 2013, 07:12 AM   #1442
xrk971 is offline xrk971  United States
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I usually model full range speakers and all the little physical details like the bends and corners make all the difference - and they show up in the measurements when done properly. It may be that subs are a different game and especially with the low pass and high pass filters applied, this suppresses any of the smaller effects normally present and impacted as a result of the geometry. The AkAbak manual shows examples where very small physical details show up and affect the final simulation's accuracy. I have modeled hundred's of speakers and almost always, in my experience, the small details end up mattering. But like I said, this may be result of a sim that is un filtered.
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Old 4th October 2013, 10:23 AM   #1443
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On the off chance, does anyone know of any suitable Australian drivers for use in this build?
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Old 4th October 2013, 01:45 PM   #1444
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what brands are easily available to you?
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Old 5th October 2013, 07:15 AM   #1445
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well not a lot really. JBL, Ande, FS-audio, major car audio brands but usually only up to 15"

FS-audio
http://www.vfmaudio.com.au/product.php?id_product=593

ANDE
JDs Sound and Lighting. Speaker Components



We don't get nearly any of the brands you can from say partsexpress and shipping costs are astronomical if ordered from the US. (usually 140% - 200% of actual product price)

Im looking to install 2-4 of these in a very small club (200-300ppl)
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Old 5th October 2013, 07:39 AM   #1446
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This driver looks good, not sure if it would work though.JDs Sound and Lighting. Ande SB18-5 18" 1000W woofer / driver

Interestingly I just found a dual 18" folded cab for $1300 from JD's. Given it has two 800W drivers in it ($600 worth) and 60KG of birch (not cheap here at all) and trim It seams like this could save me a lot of trouble and time. It seams to be similarly spec to what two th18 would do yet not sure just how good it sounds and how this double folded horn works.

JDs Sound and Lighting. Bob Audio CS218 Dual 18in double folded horn subwoofer 1600W RMS
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Old 5th October 2013, 02:51 PM   #1447
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It's a 49x20.5x27.5 cabinet. Or about 16 cubic feet. Vs about 16 cubic feet for the TH-18.
Im betting that it's loud, but the "operating frequency" lower limit of 35hz listed is most likely the -10db point (or even more than -10db)

Just a guess. But if you were looking for sub 40hz output I'm not so sure that's the best cabinet.
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Old 5th October 2013, 02:52 PM   #1448
sine143 is offline sine143  United States
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i doubt it hits 35 with ANY type of authority. Its a FLH, each 18 is crammed into a 700mm x 620mm x 520 mm cabinet (meaning horn length is very small). its probably 10 db down by the time it hits 45.

EDIT* lol mrgsr, we had the same thoughts at exactly the same time.

Last edited by sine143; 5th October 2013 at 03:13 PM.
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Old 5th October 2013, 06:22 PM   #1449
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I meant 15 cubic feet for the TH-18. It's 14.8x actually. Sorry!
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Old 6th October 2013, 12:07 AM   #1450
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Quote:
Originally Posted by reminence View Post
well not a lot really. JBL, Ande, FS-audio, major car audio brands but usually only up to 15"

FS-audio
PA SPEAKER 18" JB1800 SUBWOOFER 1200W /4 INCH COIL

ANDE
JDs Sound and Lighting. Speaker Components



We don't get nearly any of the brands you can from say partsexpress and shipping costs are astronomical if ordered from the US. (usually 140% - 200% of actual product price)

Im looking to install 2-4 of these in a very small club (200-300ppl)
The JBL driver will work in the design BUT can't say how well it will hold up to the stress of hours of use at a club. I have no idea how strong/well built the cones are
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