PDA

View Full Version : 4 E8's box question



Slo_Ride
05-30-2009, 12:57 AM
Box outer dimensions (.75 mdf) - 40" x 13.75" x 8.5" = 1.91 cubes

After subs, ports and bracing = 1.65 cubes

Box will house four E8's firing up. I have 10' of 2" pvc so I'd like to use it since it's free. Will two 2" ports 8.56" long tuned to 34hz give me good output? Also I have a choice of firing the ports down or to either the driver or passenger side, do not have room to fire up with subs. Give me your thoughts please on this design.

Power comes from a Sundown SAE-1200D = 1200 watts @ 1 ohm @ 12.8 volts.

Box will be behind the seats, raised off the floor, in a small MR2 with about 30 - 35 cubic feet of interior volume.

cx-7heaven
05-30-2009, 01:01 AM
According to specs, you a bit small on the box, and high on tuning... .6 net/30 hz is reccd per sub

Shinju
05-30-2009, 01:01 AM
Seems small to me, I have 4 in a 2.5cf ported box 40" of port for a tune of 35hz this is after displacement.

Supergumby5000
05-30-2009, 01:03 AM
the best response curve i got from an E8 was 0.6cu ft net @ 32hz, so the best possible thing i think you could do is 2.4cu ft NET @32

bones22
05-30-2009, 01:04 AM
size of your box wouldnt be any issue. they can go down in .3 - .4 each as long as you have the power. personally id just do a slot port but that ones up to you.

Slo_Ride
05-30-2009, 01:17 AM
Comes out to 4 1/8 cubes per sub. Everyone knows amp is underated and each sub will get about 350 watts each. Jacob has said that the E8's can handle the power thermally but are limited mechanically. He said it wouldn't hurt to make it a bit smaller than .6 per sub to help control sub. So do you think I should do 30hz, 32hz or 34hz? And ports down (opposite of subs) or to the side?

Slo_Ride
05-30-2009, 01:17 PM
Would I be better off using one 4" port 17.12" long instead of two 2" ports?

DNick454
05-30-2009, 06:30 PM
2" ports would be too small... each port would only provide 3.14 sq. inches of port area, so you'd need quite a few of them to achieve the needed area, and they'd have to be curved due to your dimension restrictions. You're better off with a slot port. Also, I've never personally experienced it, but a lot of people have said that they don't really like downfiring setups, although that was in pickup truck cabs, not sure if it would be the same/similar in a roadster...

Slo_Ride
05-30-2009, 06:41 PM
Yeah I think I'm gonna try one 4" port. A lot of people say you need 16 suare inches of port per cubic foot, but I just can't fit that much. I also do not have room for a slot port, plus the box is already partially built. It's not a downfiring box, the subs will be facing up. I think I'm gonna fire the port toward the passenger side of the car.

Supergumby5000
05-30-2009, 06:42 PM
Yeah I think I'm gonna try one 4" port. A lot of people say you need 16 suare inches of port per cubic foot, but I just can't fit that much. I also do not have room for a slot port, plus the box is already partially built. It's not a downfiring box, the subs will be facing up. I think I'm gonna fire the port toward the passenger side of the car.

using aero's, you can get away with more around 8-10sq in of port per cubic foot.

DNick454
05-30-2009, 06:46 PM
Actually, they did a bench test on aero's and typical slot port designs, and they measured that you can use up to 40% less port area with aero ports and still be as efficient. So you could get away with like 20 sq. inch of port area for a single port for all 4 woofers. If you don't want to pay for aero's, just use PVC pipe but don't actually put it into the piece of MDF. Make a ring that fits on the backside of the wall that is the same as the outer diameter of the PVC and then use a round-over bit around where the port comes out and it'll give it a nice flared opening and at a fraction of the cost. It won't be as efficient as a true aero port, but it'll be better than a straight opening and it'll look a load nicer.

Slo_Ride
05-30-2009, 06:52 PM
using aero's, you can get away with more around 8-10sq in of port per cubic foot.

great, didnt know that. thanks

Slo_Ride
05-31-2009, 01:33 AM
Will putting a 90 degree turn in the middle of a round port have a negative effect on output?

mmouse57
05-31-2009, 12:20 PM
nothing wrong with .6cf guys that box should do just fine