dual boxes or one big box?

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If I have 2 drivers; I was wondering what the difference would be of having a separate box for each driver as opposed to putting 2 drivers in a doubled size box and tuned accordingly.
Two boxes are stiffer than one using the same bracing, two boxes allow for more placement flexibility, and are safer for the second driver if one driver is lost due to mechanical or thermal problems.

On a more esoteric note, the reflections of either driver are also modulating both drivers in a shared box, a single driver per box has less modulation and will be a bit "cleaner".

The positive aspects of shared boxes are less material and connectors used, lowering weight, cost and build time.

Art
 
frugal-phile™
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Art states the advantages of 2 boxes pretty well.

But, if one loads the 2 woofers in a single box tightly coupled push-push (mechanically opposed, electrical in phase), then you create active vibration cancelling which yields a dramatic reduction in box load. This means the box can be much lighter with greater resistance to resonance.

I tend to get 4 next size down woofers so i can afford to build 2 push-push boxes.

It is hard to weigh the reduced box issues against (usually) better room integration without considering the room.

dave
 
If both box have the same 18mm ply then

2 Single box are better as will have less vibration than putting 2 driver in a single box. Single driver per box advantage is it has it own bracing and wont bend easily from sound waves. It will sound cleaner and smooth.

Dual driver per box can help vibrate the other drivers cone and can help to go slightly lower.
 
Perhaps I should have defined my question a little better. I'm referring to a single enclosure with 2 front-firing woofers next to each other. For the sake of this discussion, I would assume the box externals, and volumes, to be identical. The only difference between the two (bracing aside) would be that one box would have the 2 drivers sharing the same air volume as opposed to the other box having each driver using its own chamber. More or less dropping in a 0 displacement divider between the drivers and removing it.

Bracing aside, I know there's a lot of theory involved in the drivers affecting each other and, while I can't discredit it, can one actually hear the difference? Meaning, if I blindfolded myself and took a dual-loaded front firing box, then A/B-ed it against 'the same box' but with a dedicated chamber for each driver, could my ears distinguish the difference?
 
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I would love to test this to see if I can notice the difference... but so many boxes, and the cost of Baltic birch! I should have considered it in the first place.

We did a test. We made 44 litre subwoofer boxes out of 15mm BB. Braces such that it was about 7-8” for largest unbraced span (2 full width holey baces forming a vertical cross). With no drivers the box could be picked up easily with one hand. With 2 drivers it wa sreally a 2 man lift to be safe. Tested using a mechanics stethoscope i turned it up as loud as i would ever use it with no noticable vibration. Up 10 dB from there (i turned off the satellite amps) i could get noticable output from only the top — that will be fixed with the cosmetic clading — a chunk of granite or corian in a constrained layer.

push-push-SDX10-inside-view.jpg


Anyone building a 2 driver sub without taking advantage of this nearly free trick is missing a golden opportunity.

dave
 
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As to the OPs question, no division vrs division in the same boxes — except that with a real divider you get some bracing (with a caveat*) and a halving of one of the dimensions over which you can get standing waves. *(the brace should never be in the centre,this will reinforce the 1st panel resonance but it will reduce ballooning — if you want exactly the same volume, angle the partition).

Again, if the box is not already built, do consider push-push.Even if it is built, and dimensions are sufficientone could take one driver and mount it on the back, turn the box 90° so drivers are on the side — just a question of trying to get the bracing adequate.

dave
 
Bracing aside, I know there's a lot of theory involved in the drivers affecting each other and, while I can't discredit it, can one actually hear the difference? Meaning, if I blindfolded myself and took a dual-loaded front firing box, then A/B-ed it against 'the same box' but with a dedicated chamber for each driver, could my ears distinguish the difference?
Can't speak for you, but years ago I could hear the difference, (the dual box being "tighter") though not anything I'd get too excited about. That said, your wallet can definitely feel the difference when you loose two drivers because of a defect in one :eek:.

Art
 
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