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Old 8th August 2006, 01:56 AM   #1
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Default Box Build

im not sure if this is the right place to post since i have not been on here in a while.. but im sketching up an box build... and i have one question.. i use to build boxes before.. and i know what if i have two boxes firing at each other that they will cancel each other out.. even at a slight angle they will as well.. now a couple of my buddies told me that this is false and that a i could build the box i wanted... i still do not think that it is false and they will interfeire with each other.. so what does everyone think.. will they cancel each other out if they are firing at each other??? btw in trying to put 4 12s in an hatchback... Im probably get 2 to fire towards the back and 2 toward the front...
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Old 13th August 2006, 12:47 AM   #2
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cancelation IS an issue.
But it wont be total.
What you will get is 'constructive/destructive interference'.
Some frequencies will be cancelled out, others will be reinforced.

why not look at isobarik.
ok you lose the effect of the second woofer, but you gain space and aiming options.
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Old 13th August 2006, 08:02 AM   #3
Clipped is offline Clipped  Thailand
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hi, ive built plenty of boxes with the subs firing at each other...you wont have any serious cancellation issues unless you wire the subs out of polarity with each other.

the distance between the two sub faces is more important...you have to adjust the space to find the sweet spot...its usually around 1 foot for twelves.

one of the best sounding cars ive built had the subs facing each other...located to the very back of the trunk...bass blended in perfectly with the mids, very little phase/time lag between the mids and bass...

if total spl is what your after though, this may not be the way to go...but the you could always add a middle chamber and turn it into a bandpass box (carefully)
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Old 13th August 2006, 09:29 AM   #4
Did it Himself
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Subs facing each other is not an issue. Subs facing opposite directions (like you propose one firing front and another firing back) is an issue and come cancellation will occur. The close these subs are together the more concellation you will get. It's a bad idea IMO as it will cost you bass as bass cancels more.
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Old 19th August 2006, 07:33 AM   #5
d3cibel is offline d3cibel  Indonesia
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Phase problem will cause cancellation..not the box configuration, simply match both subwoofers in phase or both out of phase
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Old 19th August 2006, 10:02 AM   #6
djQUAN is offline djQUAN  Philippines
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Quote:
Originally posted by richie00boy
Subs facing each other is not an issue. Subs facing opposite directions (like you propose one firing front and another firing back) is an issue and come cancellation will occur. The close these subs are together the more concellation you will get. It's a bad idea IMO as it will cost you bass as bass cancels more.

this is not true in some cases. if you put the subs facing on opposite directions and change the polarity of one sub, then cancellation will not occur.

I have built a bass bin for my older suv using two 12's facing each other into a chamber which opens into the cabin. two sealed boxes with entry level subs beating other competitors with vented boxes and higher end units. they found it hard to believe.
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Old 20th August 2006, 11:21 AM   #7
micb is offline micb  United Kingdom
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How much space will you have between the drivers?

As long as the subs have plenty or space to fire in to then you should be fine.
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Old 20th August 2006, 08:48 PM   #8
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lol yes i forgot about polarity
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Old 20th August 2006, 09:16 PM   #9
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how much space is needed between the subs???
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Old 20th August 2006, 09:22 PM   #10
micb is offline micb  United Kingdom
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5-6 inches.

The JL 1000/1 is 1.5 ohm stable so personally i'd go for 3 12's (1.3 ohms) all firing in the same direction, in a vented alignment tuned good and low!
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