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SPLThunder
05-11-2003, 12:26 PM
So this will be my third box for these set of subs. My first one i blew at the seals. The one i am on now has nothing wrong with but i wanted to aim everything a different direction.

I am going to point the subs toward the rear seats and leave about 3 inches between the sub faces and the seats. Since my rear seats dont fold down. (the ONLY thing i miss about my escort) I want to port the box through the arm rest. This might pose a problem but not too big. I will no longer be able to brace the box directly in the middle because a big 4"x6.28" square port will be in the way. (same as 2 4" round) I will see how much room i have but i will probably brace it on both sides of the port. Another problem with the port is the angle of the arm rest. I want the port to be flush with the armrest but that means i must have a port that is either going at a angle into my box or the ends be cut at an angle. Question is will a port with ends cut at an angle screw up the tuning?
Sound waves were my least favorite subject in physics.

Another question is do you think 5/8' would be thick enough since i am porting the box. There should be less pressure against the inside because it is being released through the port.

paikiah
05-11-2003, 12:46 PM
Originally posted by SPLThunder
So this will be my third box for these set of subs. My first one i blew at the seals. The one i am on now has nothing wrong with but i wanted to aim everything a different direction.

I am going to point the subs toward the rear seats and leave about 3 inches between the sub faces and the seats. Since my rear seats dont fold down. (the ONLY thing i miss about my escort) I want to port the box through the arm rest. This might pose a problem but not too big. I will no longer be able to brace the box directly in the middle because a big 4"x6.28" square port will be in the way. (same as 2 4" round) I will see how much room i have but i will probably brace it on both sides of the port. Another problem with the port is the angle of the arm rest. I want the port to be flush with the armrest but that means i must have a port that is either going at a angle into my box or the ends be cut at an angle. Question is will a port with ends cut at an angle screw up the tuning?
Sound waves were my least favorite subject in physics.

Another question is do you think 5/8' would be thick enough since i am porting the box. There should be less pressure against the inside because it is being released through the port.

I think slashing the end would mean that the length of the port is bound to be different. Unless your'e familiar wit horns, you should take it that the shortest point of the port is your legth, or soemthing like that (that's what I seems to me)

As for bracing, since you have the port in the middle, you could USE that to brace your box :) In fact, you'd be saving wood, by having a piece of wood under and over the ports, if the port is floating in the middle of the box.. Or it if it runs top to bottom, then you've already got yourself a braced box. :)

I think the thickness would determine flexing. I'm sure it won't BLOW (if it's not too powerful), but flexing will cost SPL numbers.

bigred78797
05-11-2003, 10:16 PM
By cutting the port to an angle won't make tooo much of a difference unless it is a drastic cut. like 50 degrees or so. Doing that also gives you a slight increase in port area at the end, but the affect on the sound would probably be unnoticable to the average ear. Hope that i was of some assistance :). As for the 5/8 thickness i dunno, i always use 3/4 MDF or a whole bunch of fiberglass. I just know that with my ported system there is a whole lot of pressure when a beat kicks in, but because it is well sealed and very well put togeter it doesn't budge. My first attempt at boxing failed also, blew the top right off, it was funny. What kind of fasteners do u use?

awalbert88
05-12-2003, 12:01 AM
My earliest attempt at a box was so sad and funny that I'm shocked it didn't catch fire or something. The first serious attempt at a box was for my 12W7, and I think I overbuilt it, because it couldn't have blown apart if you filled it with dynamite. Air leaks? Hah, not a chance. The box I'm using now is probably not quite as strong (having built it inside the trunk, there was no way to rest one of the car's tires on it for a test like I did with the other box). However, it's more than strong enough to withstand the forces I'm putting on it. I use 3/4" MDF secured by 3 2" screws per side (more for longer boxes) and liquid nails, with either caulking or expanding foam used to help seal it.

bigred78797
05-12-2003, 12:10 AM
I my boxes now are like rocks.. lol. I usually put a 2" screw in every 3" or 4". Then i use my own mixure of adhesive culk mixed with a superglue. Just for fun i took all the screws out of one of my boxes to see how strong it was... the Audiobahns didn't even break a seal. I threw it off the roof of my house... nothing... untill the second toss. It was a smaller box only about 1.25 ft^3.

SPLThunder
05-12-2003, 12:14 AM
yes i am a fanatic too. since i burst my first box at the seams i wanted absolutly no way for anything to happen to this box. The one i currently have in my car weighs a ton.
1 1/8" MDF Sealed with liquid nails (2 bottles), 2 1/2" screws, and silicon sealant on the inside.
Needless to say that is why i asked about the 5/8" mdf. I feel as if my car has gotten much slower ever since i put that thing in. still running 16s though just a little higher. :) Not bad for heavier than stock

abcdefg
05-12-2003, 12:23 AM
Originally posted by awalbert88
My earliest attempt at a box was so sad and funny that I'm shocked it didn't catch fire or something. The first serious attempt at a box was for my 12W7, and I think I overbuilt it, because it couldn't have blown apart if you filled it with dynamite. Air leaks? Hah, not a chance. The box I'm using now is probably not quite as strong (having built it inside the trunk, there was no way to rest one of the car's tires on it for a test like I did with the other box). However, it's more than strong enough to withstand the forces I'm putting on it. I use 3/4" MDF secured by 3 2" screws per side (more for longer boxes) and liquid nails, with either caulking or expanding foam used to help seal it.


just 3 screws perside???? i got a screw every 1 inch almost

paikiah
05-12-2003, 12:39 AM
i've built quite a few boxes now, for my superiors in the base.. most of them sealed. (easier). It was made for cheap boxes. Didn't sound that differnet (i.e. crappy), but they were very happy with the results.

For my own use, I've used a whole LOT of screws. The ported box that sounded the loudest was thanks to courtesy of Jmac's specs. Unfortuantely, as it was a test box, it doesn't fit my car, and had to throw it away after trying it.

I don't know about you guys, but I take about 3~4 days at least to build one box. I let the glue cure for 24 hours, befroe moving along to the next step. First, I glue the top and side walls. Cure. then the back and front. Cure. Apply silicone. Cure. sink and drill holes for LOTS of screws and tighten as needed.

awalbert88
05-12-2003, 02:03 AM
It only takes me about four hours to build a box, plus drying time. One of these days, I want to build a nice, big ported box, borrow a nice powerful amp from somebody, and see just what my W7 can do in such an enclosure. I'm expecting that sealed sounds better, but I'd like to find out how it sounds in a ported box.