HELP - OB 1800W woofer

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k__x

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HELP - OB 1800W woofer
« on: 11 Oct 2009, 01:17 am »
hi
i have a PA system (open space) with 16 units of 12" Beyma 12P1000ND (1800W program) :
http://www.usspeaker.com/beyma%2012p1000Nd-1.htm

 in a  small  bass-reflex cube woofer box (34x34x34 cm) each, with 80Hz tuning (Work Frequency Response: +- 60Hz - 250Hz), but they are very bad playing lower frequencies as you know.

I want to have woofers playing 30Hz ore lower frequencies with good performance in a small and light box if possible, so i think in sealed box, but they will be much more heavier and i think the performance will not be as good as Open-Baffle ore U-frame, i don?t know... :oops:

can you advice me, or tell me names of simulation software please ?
 :|
« Last Edit: 11 Oct 2009, 12:38 pm by k__x »

Bob in St. Louis

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Re: HELP - OB 1800W woofer
« Reply #1 on: 11 Oct 2009, 03:02 pm »
Infinite baffle.  aa

k__x

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Re: HELP - OB 1800W woofer
« Reply #2 on: 11 Oct 2009, 07:07 pm »
Infinite baffle.  aa

thanks, but how can i do that?  :|

opnly bafld

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Re: HELP - OB 1800W woofer
« Reply #3 on: 11 Oct 2009, 07:33 pm »
Does it need to be portable for a PA system?

Lin

k__x

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Re: HELP - OB 1800W woofer
« Reply #4 on: 11 Oct 2009, 07:37 pm »
Does it need to be portable for a PA system?

Lin

yes, for now, each bass-reflex box (35cm x 35cm x 35cm) with 1 speaker have +- 9 kg (20 lb).



Bob in St. Louis

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Re: HELP - OB 1800W woofer
« Reply #5 on: 11 Oct 2009, 07:43 pm »
Well, here's the quicky laymans definition:
An Infinite Baffle ("IB") is a speaker that keeps the rear wave (everything behind the cone) from entering the listening area. It requires you to have a hole known as a 'throat' that focuses the sound into the room, but sends the rear wave into an attic, basement, outside, or another room. The cubic area of the area that contains the rear wave should be at least 10 times the Vas of the drivers used (ideally). Some folks say you can get as low as 5x Vas, but the purists say ten. Mine is just a hair under 5x.
An IB consists of even amounts of large drivers (15" & 18" are most popular).

The "guru's" of IB have a forum with lots of juicy photos. The site is > HERE < and is called "the cult of the infinitely baffled".

Another advantage of IB is the box doesn't have to be pretty, or fancy looking. It's hidden away in another area. The opening of the throat is covered by a decorative grate. That's the only thing that can be seen from the listening area. So good carpentry skills are optional.  :lol:

Bob

EDIT: Ahhh crap.....I didn't catch the comment about portability.  :duh: :duh:
Good catch Lin.
Well Mr. K__x, when your'e ready to have system that's NOT portable, check into IB.

opnly bafld

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Re: HELP - OB 1800W woofer
« Reply #6 on: 11 Oct 2009, 07:54 pm »
To get anywhere near 30hz in a very large area at high spls think big, really big and heavy boxes with big drivers.

Lin

Bob in St. Louis

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Re: HELP - OB 1800W woofer
« Reply #7 on: 11 Oct 2009, 09:35 pm »
Yip. What he said.
Like a couple guitar cabinet looking monsters with quads of 15 or 18" drivers.
Big and heavy. Would need wheels to move around.

Bob

p.s. Actually, now that I think about it, how about one of those TL's with a 15 in it?  :dunno:
Would still be pretty big though.

k__x

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Re: HELP - OB 1800W woofer
« Reply #8 on: 11 Oct 2009, 11:23 pm »
thanks for all of your help information, but i build many 15" and 18" bass-reflex and isobaric speakers and i want to go to other type of woofers, than i choose 12", most light, with fast response and better sound quality but one of my objective is to control the "back sound", i dont want to have omnidectional low frequencies in the stage, so i think in dipole loudspeakers.

im thinking to buy more 16 units in the future to get more SPL...