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Old 14th December 2007, 04:35 PM   #11
Kensai is offline Kensai  United States
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Well, closed will be tighter and roll off more smoothly, but you won't get much stock (though its a tiny enclosure), and if you add even just 2ohms, the sealed volume is out of hand and at 3ohms it nearly doubles that, so I'm guessing you'll need to go ported just to get a reasonable size box. A 20.6 l box tuned to about 27.5Hz is what WinISD is showing me will work nice. Should get you pretty flat to around 30Hz with room lift and whatnot giving you fairly useful output to 23-25 (this is all assuming isobarik loading). If you tune it to 32Hz, you'll lose a few Hz on the bottom end, but it'll flatten the response out to nearly ruler between 30 and 185. Designed this way you'll have a 4th order rolloff at the bottom and a nice first order on top so it should be pretty easy to integrate and keep from distortion due to infrasonics.

Just 2 drivers facing forward, the enclosure volume actually goes up 4x and it gets you similar flat response about 2dB down from the isobaric with a few Hz at the bottom and the top end reaching up to about 350Hz before rolling off.

I would vote for the isobarik load tuned to 32Hz, but that's just me looking at sims in WinISD. I've never actually used an isobarik, so I have no idea what they actually sound like.

Kensai
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Old 15th December 2007, 12:57 PM   #12
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Well,

I will go for the isobaric configuration, and I'm beginning to learn how to use winisd.

I could use a volume of 28l tuned to 25hz (flat to 30 hz, -3db at 24hz), vent D 60mm L 43,2cm
or V 19l tuned at 28hz (flat to 40, -3db at 28 hz) with a vent of D 60mm
and a lenght of 50 cm............ (too much!)

I've noticed a strange think: the reflex vent that winisd indicate to tune the box to 28-30 hz is VERY long or VERY thin: both solutions are problematic, I think: too thin will produce airflow noise, too long tube will resonate and/or be problematic storing it in the box.


DOH!

Any ideas?
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Old 15th December 2007, 08:06 PM   #13
MPM is offline MPM  United States
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Join Date: Sep 2004
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If Tang Band drivers are available where you live maybe you should consider a horn sub for your horns. Just seems an appropiate match. I'm using the Tuba 18 and its works great. Its what I consider a very musical sub.

www.billfitzmaurice.com
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Old 16th December 2007, 05:07 PM   #14
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Join Date: Jul 2007
No martini no party!

I've seen your link, and think it could be nice but my few bucks are a no-no for buying new drivers. For me, diy is money saving too... so, if I can re-utilize the drivers I own..

Thanks for the advice anyway.

This diy community is a great resource to learn and have fun even without searching hi-end absolute performances... (but often i read the supermegaiperquality sound researcher and dream listening this kind of beauties..)

Ps: sorry for my poor english. It sucks, but maybe can be understood.
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Old 17th December 2007, 09:26 AM   #15
sreten is offline sreten  United Kingdom
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Hi,

As you may have noticed going reflexed isobaric with said drivers
you end up with silly sized ports, you would have to use PR's.

Basically the drivers are not really suitable for isobaric reflexed.
(could work as a 20 to 25L double pair sealed in push
push or the same in 33 to 35 L tuned to 25 / 26 Hz)

/sreten.
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Old 17th December 2007, 12:45 PM   #16
Kensai is offline Kensai  United States
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24L, 2" port at about 9.5" should do it. Tunes to 30 and give a sim from 28Hz to 185Hz within 2dB. A 2" port should be fine as far as port noise goes. IMO, there's always noise with reflex cabinets. Just one of the tradeoffs for increased extension.

Let us know how it goes.

Kensai
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Old 20th December 2007, 06:40 PM   #17
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I'll do for sure!

Now I'm collecting plywood, glue, pvc tubes....

I'll begin i a few days to build the most economical and beautiful sub in the world!


Thanks all, again..
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