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Old 7th February 2010, 05:28 PM   #1
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Default Need to build "directional" subs.

Hey Guys i have 2 15 inch JBL subs. one is a 2225h and the other a 2226h. i need to build a "directional subwoofer out of them. both in the same cabinet if at all possible. they would be in an enclosure with a square back and a triangle sticking out from the front such that the subs are on the outside of the front. one pointing 45 degrees left. the other right. they are to be used for my company so need to be tough, loud, and solid. i am thinking of building 2 of these if i can get another 2 15 inch subs. i am also thinking of using a behringer EP2000 2000 watt stereo amplifier. which will do 500 watts per channel at 4 ohms. I would also like this sub to be able to be "table danced" on with as many people as the size will hold. I also need it to be as loud as possible, although it can be more laid back because i use 2 18 inch subs as well with 136dB each. couple to i believe 139 dB with the +3 increase per additional sub. i would however like it to hit at least 115 dB. these subs are rccomended to be in an enclosure of between 3 and 8 cubic feet. the two together would need 6 to 16 cubic feet correct? the height needs to be between 17 and 24 inches tall to fit under a table if neccessary. now for the next question. one is rated at 600 watts and the other 400 watts. can i use them both on the same channel of an amplifier without being worried about blowing the 400 watt one. is there a way to use resistors or the like to tone down the wattage to the one? i will provide TS paramaters if requested. ported is fine sealed will probably work better. but i would really like a TH or similar enclosure. but since it has to be portable it should probably be sealed to educe size. now the height restrictions will allow it to fit through a door. but the weight should be manageable by 2 people. IE no more than 300 pounds. also it will probably have to be lugged up and down stairs as well. as some venues have stairs in order to get to the performance room. I also have 2 10 inch subs to work with as well just in case i need to use them. another thing i have is a 150 watt 8 ohm plate amp that i could use if it would acceptably power the 15's. i hope i didnt get too off topic and provided enough pertinent information to be able to get this designed some. for bracing i will probably use 1x1's or 2x2's because then theres no fancy cuting aside from the angles to brace the front. i will probably use 3/4 inch plywood or MDF to build the cabinet itself. plywood is preferable. and i dont want to have to do too many crazy cuts as well. i am pretty skilled with woodworking as well so i can rout the hole and countersink the subs for protection. i will probably be putting a grill over the subs as well... Long read but i figured i should provide all pertinent information.
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Old 7th February 2010, 08:04 PM   #2
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You seem to have a lot of projects. How many that you have posted about are underway?
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Old 7th February 2010, 08:13 PM   #3
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you mean in other threads? i built a couple of them then posted about others and the threads died GRRRR. in this one i am referring to only 1
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Old 7th February 2010, 08:17 PM   #4
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The concept of "directional" is a bit odd for a sub-woofer. For anything much below 300Hz, is is not possible to tell the direction from which the sound comes - your ears are just too close together.
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Old 7th February 2010, 08:19 PM   #5
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i know i called it "directional" for a reason. basically all i need is a sub with the drivers 60-90 degrees from each other pointing out so that it can be placed in the middle with the other subs 30 feet on either side to fill up the middle of the room
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Old 7th February 2010, 08:21 PM   #6
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i don't know the numbers of the jbl's you listed, but it seems you are planning to walk the long way around the mountain when you could just turn around and be there.

building monster ported or sealed cabs to be carried up/down stairs and be really loud doesn't make sense.

why not sell the two non-matching speakers you have(problem solved). buy two 12" speakers that correspond to a sub-horn design. they will be 1/4 the weight. use 1/4 the power. and have the same spl and thunderous effect.

i have two 15" loaded sub-horns that when coupled at a 45 degree will knock you down or make you sick with such a strong thump(literally). all this with a 500 watt amp. at half volume you will have to leave the room from too much bass. they weigh 75lbs each.

it does require more time to build than a cubed box, but the outcome is way worth it.

you can also check out this forum for "tapped horn" for a slightly less loud horn, but easier to build.



no need for directional sub anything. to fill the room just turn it up or down. if you have a dead spot you have a out of phase problem. place the sub in the corner of the room and use the natural effects of the room to fill it up. i got a tiny sub in my living room corner that can be heard loud and clear all over the house in everyroom!!!!

Last edited by oilcanracer; 7th February 2010 at 08:26 PM.
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Old 7th February 2010, 08:24 PM   #7
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im not too concerned with weight my amp rig is over 300 pounds and my other 2 subs are over 100 pounds each and need to be carted up and down stairs to get out of my storage area. so weight as long as it can be handled by 2 people isnt a problem. width can be up to 8 feet and depth up to 3 feet. the only constricting dimension is height. which would have to fit under a table at just under 24 inches.
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Old 7th February 2010, 08:25 PM   #8
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(EDIT: Many posts while I was typing)

1. Never heard of a directional sub.
2. These are woofers, not subs.
3. Avoid using different woofers in the same box
4. Why do you want persons dancing on the woofers and how will that happen if they are under a table?
5. Why do you need these when you already have 18" units? Use multiples of them not different drivers. (i am assuming these are the units you bought for $125?)
6. What's up with your desired placement of the drivers on the box?
7. Forget the 10" woofers.
8. Plywood is good, so is bracing and rebating your drivers.
9. Sealed will be the easiest to manage, TH gives you bang for the buck.
10. Try to avoid resistors in the woofer path, that just wastes power.

I let others steer you from here on in.
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Old 7th February 2010, 08:26 PM   #9
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to el'ol its quote unqoute directional for sarcasm. i dont want true directivity. i want it to fill up the middle of the room so my other subs can be a bit quieter and not be risked to blow. also so that i can have table dancers at gigs. Im a professional DJ starting a company so i figure instead of buying another $1000 sub i would build it with what i had.
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Old 7th February 2010, 08:30 PM   #10
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FCOL DIRECTIVITY IS NOT THE DISIRE.
2 i just need some bass it doesnt have to be sub bass or even low bass just midbass.
3 i knew that but was wondering if it could be done.
4 if i had table dancers they wouldnt be under the table ... DUH
5 the JBLS are the ones i got for $125, the 18s will be 60 feet apart i need something in the middle so the bass is more present.
6 so as to direct sound more outwards and fill the space
7 i figured someone would say that
8 i knew plywood would be good as well as bracing
9 i like sealed but would wilingly go with TH if its more efficient
10 i also knew resistors would be a bad idea
I hope this clears up some of your pre-mis-conceptions
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