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And other question about subwoofer

795 views 30 replies 8 participants last post by  edben 
#1 ·
First thanks for all the response of everyone on my previews subject about ported box it help me a lot!!

I just read about dual opposing woofer in a sealed box!

Anyone as experience with this ?
It looks like a nice way of making sub work! From what i read you gain 6db plus you remove box vibration ?

Im curious is it possible to build a dual 18 opposing configuration?
Thanks!


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#2 ·
I believe you only gain 3 dbs by adding a second identical sub
 
#3 ·
I've done it and yes it helps with canceling vibrations. It just makes the cabinet twice as big, which may limit placement options, and also reduces the ability to spread the subs to as many locations.

I swapped back to individual boxes for those exact reasons. In my opinion the benefits of spreading the subs around the room and having more placement options outweighs the vibrations. I can combat them with bracing.
 
#5 ·
The 6dB gain comes in from adding the second woofer and amplifier channel. Doesn't really have anything to do with a dual opposed cabinet. You can park two single driver cabinets near each other and get the same result.

I have four UM18s in two opposed cabinets in my living room. They don't vibrate at all, even remotes don't slide around on them, and that's sitting on carpet with no concern about the sponginess of the floor. Cabinets are about 40" tall by 24" by 20", and the woofers are near the top of the cabinet.
 
#6 ·
The 6dB gain comes in from adding the second woofer and amplifier channel. .


if you have a maxed out sub with 1000 watts producing 120db and add another maxed out sub with 1000 watts producing another 120 db you only gain 3 db of additional output
 
#7 ·
I've always heard doubling the power AND drivers would result in roughly a 6db increase (real world increase varies).

Doubling drivers OR power (if driver could handle it) would be a 3db increase.

Someone feel free to correct if I'm wrong.
 
#10 ·
If you check the picture below that is what I have for my HST18. I wanted to save some space and still have the ideal box size for these subs. As far as vibration only at extreme levels will there be some otherwise you could set a glass of water on the top plate and it would not move. As it sits its 8cu.ft. at lower volumes my DS4's in stacked sealed have a little more output but overall very happy with how it turned out. I used a vinyl wrap did not turn out perfect but considering it was the first time using vinyl not bad it blends with my furniture.
 

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#12 ·
I just read about dual opposing woofer in a sealed box!

Anyone as experience with this ?
It looks like a nice way of making sub work! From what i read you gain 6db plus you remove box vibration ?
I've built a few of them, but dual opposed sealed still gives you the single driver sealed response 6dB louder. You miss the added ouput at the bottom of the passband you get with ported.

You can do dual opposed ported too (built a few of those as well). You simple double the box volume from a single and adjust the port to suit.
 
#25 ·
Here is my none technical take. If you want to save space by all means the DO is great. At higher volumes its great but being truthful and I was told this by others 2 sealed boxes will outperform a DO and I have to admit it to a point. The other image that I posted is of 2 MartyCubes, I wrapped them in vinyl and used some trim to make it look like one box. I have a nu 6000 on those and an A14K on the DO. I am not trying to imply the sealed out performs the DO its just the sealed is just a tad more efficient. Now if I had another 3000.00 I would definitely get 2 more HST18's and another A14k and build another DO. The current is 39" x 21.5" x 21.5" so I figure with the 2 drvrs and the bracing approx. 8cu.ft. Standing on end the footprint is reasonable that is why I like it but if you have the space go big.
 
#27 ·
I got my idea of building the DO from this:

http://www.bossobass.com/Bossobass.com/BB, In Depth 3.html

This should give you all the info you need. Overall I am quite happy with the DO my system does not have to be perfect but from what I have had in the past this is the best I have ever had. If I had the space there is the possibility I would still go with DO. To me space is an issue. That is a big reason for me going with it look it sits in the corner. According to REW I am right at 10hz with this box when I watch Star Wars Episode 1 when they start the egines for the Pod Race its killer, WOTW , Hulk , etc. I get serious rumble in my room. When I listen to bands like Tool or KMFDM, Pink Floyd, it sounds like a concert. Its not perfect but its different most have ported or sealed ( I happen to have the DO and 4 sealed ). At any rate I like it.
 
#28 ·
I got my idea of building the DO from this:

http://www.bossobass.com/Bossobass.com/BB, In Depth 3.html

This should give you all the info you need. Overall I am quite happy with the DO my system does not have to be perfect but from what I have had in the past this is the best I have ever had. If I had the space there is the possibility I would still go with DO. To me space is an issue. That is a big reason for me going with it look it sits in the corner. According to REW I am right at 10hz with this box when I watch Star Wars Episode 1 when they start the egines for the Pod Race its killer, WOTW , Hulk , etc. I get serious rumble in my room. When I listen to bands like Tool or KMFDM, Pink Floyd, it sounds like a concert. Its not perfect but its different most have ported or sealed ( I happen to have the DO and 4 sealed ). At any rate I like it.

Ok maybe this help decide if i do a dual opposed build my 2 dayton 18 will be wired in serie for a total of 8 ohm load they are 1000 watt rms each ( many folk apply 1500-2000max as they are power hungry ) is it possible to do? ( was thinking one big crown amp that can load 8 ohm bridge + one mini 2x4 dsp )
 
#29 ·
If the UM18 do well in a sealed then great. For ex. my HST's do best in a 4 cuft. cabinet so to build the DO just double the size. As far as amps go bang for the buck is the nu6000. It may not be the best but for what it does even though its over rated price wise nothing compares. If you are going to cut your own wood you need to consider the inside dimensions of the box. In my case the outside is 39 x 21.5 x 21.5 so subtract 1.5" from all dimensions ( I used .75 mdf ) then multiply 37.5 x 20 x 20 = then divide by 1728 =8.66 So I figure between the bracing and the 2 subs I am right at 8. As far as wiring if you get the nu6000 ( your choice ) the amp cannot be bridged wire each sub to its own channel. At 4 ohms you will have plenty depending on what you read 1900 to 2200 watts per side. Also you do not need to wire out of phase w/ each other just wire like any other box. Forgive me if I did not explain it right but seriously the box does pound and that is no joke!!
 
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