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-   -   1 big box Vs 2 small boxes. (https://www.diyaudio.com/forums/subwoofers/89771-1-box-vs-2-boxes.html)

JoeM 6th November 2006 10:16 AM

1 big box Vs 2 small boxes.
 
Any difference putting two of the same sub drivers into one, say 100 litre sealed box as apposed to each driver in its own 50 litre box? Woodwork/bracing issues aside.
Trying to compare what effect it might have on excursion limits, SPL ect in Winisd but you cant model the output of 2 'seperate' boxes.

sreten 6th November 2006 10:35 AM

Hi,

With 2 boxes you can smooth room response with assymetric placement.
Other than that there is no real diffrence between the two options.

:)/sreten.

richie00boy 6th November 2006 10:37 AM

Acoustic performance will be identical between the two, as will the load on the amplifier. The benefits will be it's easier to make a stiffer/deader small box, and placement options are more which is beneficial as sreten pointed out. Downsides none that I can think of, other than possible form-factor. Unless you put them so far apart that the acoustic coupling does not happen.

Collo 6th November 2006 09:28 PM

If you happened to be looking a ported boxes, going to a single box might give you an extra choice of ports

If your port velocity was excessive with the pair of boxes, you would normally have to go to a larger port, or a pair of ports. This might be more than you actually need, resulting in overly long ports.

With a single box, you have twice the volume, so the port is roughly half the length. You have two drivers, so you need roughly twice the area on the port, which makes it twice as long - getting you back to the original length, only larger diameter.

This might not seem any advantage, but you might end up with a single 6inch port instead of a 4incher in each of the separate boxes.

RobWells 6th November 2006 10:07 PM

In the single box you can also mount push push to cancel vibrations.

Rob.

JoeM 7th November 2006 01:25 AM

"Push push", now this is something Im seeing mentioned more and more. It isnt outlined in Vance Dickason's book. (is it isobarik?) Trying to find out more about it. Would this simply be the drivers at each end of a 100L sonotube, one facing in and one out, both wired in phase?
Are the any dissadvantages to it over one single sealed box? Does the basket frame become an issue of crossed at 80Hz?

richie00boy 7th November 2006 08:46 AM

Basically it's as you say, one driver on each end of a tube or opposing sides of a box. It's not isobaric so box volume is still doubled.

kimado 16th November 2006 03:51 PM

I might be confused but; although the drivers are electrically in phase because they are on opposite sides of the box their cone movement would oppose each other? would that make it isobaric?

richie00boy 16th November 2006 04:03 PM

Isobaric cones don't move opposite, they move together thus doubling cone mass which is why box volume is halved. They also need to be tightly/closely coupled.

BassAwdyO 18th November 2006 01:48 AM

Yes there may be some confusion with push push mounting, but basically you are making a bipole(if woofers were directional).

The woofer on the front of the box moves out(with respect to the box) with a positive signal, and the woofer on the back of the box also moves out with a positive signal.... The advantage is in vibration cancelation... instead of the inertia of a single cone vibrating the box, the net inertia is zero(since the two cones inertial forces cancel). The sound pressure remains the same.


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