View Full Version : Sealed enclosure, multiple drivers.
04-18-2003, 07:10 PM
I'm looking for information for specific designs for an enclosure housing three drivers.
1. If I were to mount two drivers forward and one firing to the rear, what should be the distance from each magnet in relation to its neighbors body? (Obviously, the magnets should not touch the neighboring body.)
2. If the volume for each driver should be (for simplicity) 1 cubic foot, should each driver be isolated in 1 cubic foot chambers or is it OK to have the three in one 3 cubic foot chamber?
3. If an enclosure was not a trapezoid or cube or rectangle, in other words, if the enclosure was an "L" shape, will this affect performance so long as the volume is to spec? (Trunk space is critical so I can carry my kayaking gear.)
Thanks fellow Polkies!
04-19-2003, 11:49 PM
1 - i would not mount 2 forward / 1 rear -- i could be wrong but i think that would throw them out of phase depending on how far the walls were from the front one ... and how far from the rear one. if they're not even factors of the mean wavelength of the woofer's frequency range, then you're probably in ****.
however, you can mount one of them inverted --- all "facing" in one direction, but two firing out of the box, one firing into the box -- simply swap positive and negative wires on the one firing inward.
2- you CAN mount 3 woofers in a single chamber that is three times the required volume for one woofer. However, I'm no fan of it, and a lot of other people will tell u the same, if the woofers are not in perfect phase (if they're not off the same channel of the amplifier) they're not going to perform to full potential... the benfits of putting little "walls" inside your box (so each sub has its own chamber) is that the woofer is functioning exactly per its design, in its own isolated air space, with nothing to throw a monkey wrench into its performance. when using more than one sub in a chamber you are relying on the cone of woofer A to basically serve as part of the "wall of the box" for woofer B and visa versa. with low power subs this is usually not a bit problem as nuances only occur on a small level... but bump up to a 500 - 1000 watt rms subwoofer and u'll start to notice differences between the sounds of the two box designs.
3- unless you start to create a geometric shape that counteracts the natural motion of the woofer and the production of sound... (ie a perfect globe - i haven't determined why, but woofers in a round enclosure tend to sound like junk) then it can be said that "air space is airspace" and a box that is 6 inches deep, a foot tall, and 3 feet wide is the same as a box that is 18inches by 18inches by 18inches. same statement applies to an L --- you can bust it down to a nitty gritty level and analyze how the waves bang around inside the box. but like i said unless you're reallllllllyyyyyy gettin into something stupid like say a box that is actually two boxes.... you've got a woofer that needs 1.5 cubes.. so u build two boxes... one box is 0.75 cubes, so is the other.. and to connect them you have a piece of PVC pipe of 1" diameter... in that case airspace "is not" airspace. so to answer your question -- an L is not a problem.. i've seen several L shaped boxes work fine.. as well as U shaped boxes.
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