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wesl56
07-07-2006, 11:36 AM
yay im building a 34x13.5x19 box this weekend 1.7 cubes per sub @ 32hz... for my type Rs powered by 800rms a piece

gonna do sound deading tonite ive got 2 25'x1' rolls of mat and gonna use some of that "great stuff" to spray inside all the pannels... start cuttin the wood tom.

just one question i havent been able to find a solid answer on.. what are the advantages/disadvantages of having each sub in its own ported chamber as to having both of them share the same ported chamber?

ive seen lots of boxes built both ways but not really sure if there is a difference in anything....


this is how im looking to do mine:
http://www.mypicturespace.com/uploads/507e8e43d4.jpg (http://www.mypicturespace.com)

djman37
07-07-2006, 12:05 PM
advantage: IF 1 subs takes a crap, the airspace for the remaining sub stays constant to prevent blowing from twice it's recommended air volume.
Boxes are usually, by way of dividing airspace, better braced.
disadvantage: wiring is a little more of a PITA. More cuts to be made. slightly heavier.

that's a short list.

xluben
07-07-2006, 01:05 PM
i don't know if that's enough port area

here's a single chamber moe lester box with similar specs and look how much port area it has:

http://img10.imageshack.us/img10/4435/35cubes32hz50sqin6lw.png

i think 50 in^2 or more is recommended for 2, 12's

chozen1
07-07-2006, 01:14 PM
for 2 type r 12's u need atleast 50in^2 of port

wesl56
07-07-2006, 02:41 PM
hm okay.. well if the only disadvantages of doing seperate chambers is the extra work, i think ill just do that, because each sub is gonna have its own seperate amp, and i guess it would be better to keep them seperate just incase the amps arent acting exactly identical, or if one goes out...but there is no difference in spl or sq by having them seperated with thier own smaller ports or together with one big one?

and in that sketch, my bad i meant to make the ports 1.5" wide, so 1.5x12 each port will have an area of 25 in^2 which sould be good.. that also keeps them in a perfect 1:8 ratio

djman37
07-07-2006, 04:23 PM
hm okay.. well if the only disadvantages of doing seperate chambers is the extra work, i think ill just do that, because each sub is gonna have its own seperate amp, and i guess it would be better to keep them seperate just incase the amps arent acting exactly identical, or if one goes out...but there is no difference in spl or sq by having them seperated with thier own smaller ports or together with one big one?

and in that sketch, my bad i meant to make the ports 1.5" wide, so 1.5x12 each port will have an area of 25 in^2 which sould be good.. that also keeps them in a perfect 1:8 ratio

^^^^exactly.

wider port width will keep the air speed at the port down which means less port noise. also round your corners ESPECIALLY at the openings.

thatkidbob
07-08-2006, 06:44 AM
^^^^exactly.

wider port width will keep the air speed at the port down which means less port noise. also round your corners ESPECIALLY at the openings.also... lower vent velocity given the same box/power/subs = better air coupling and more radiating area = more LOUD :D

jesuspunk25
07-08-2006, 01:07 PM
don't mean to hijack this thread so don't let that happen, but how likely is it that somebody will blow a sub with running only 2/3 of the rms power? This topic made me reconsider just doing 1 chamber for both so I figured I'd see if I'm likely to blow a sub anyway.

djman37
07-08-2006, 05:56 PM
don't mean to hijack this thread so don't let that happen, but how likely is it that somebody will blow a sub with running only 2/3 of the rms power? This topic made me reconsider just doing 1 chamber for both so I figured I'd see if I'm likely to blow a sub anyway.

You have to consider that sub ratings are usually in the spec'ed boxes, not free-air or in twice the recommended airspace.
Try to put a sub free-air and see if it'll go to RMS at a low freq. same thing happens when you play a ported box too low, the sub unloads and acts as if it were free-air.
It's like fusing...only comes in handy IF something goes wrong.

jesuspunk25
07-08-2006, 08:07 PM
So it just comes down to "better safe than sorry." I think I'm just going to go with 2 separate boxes so if one blows I can sell the other or just keep one box in my car.